Engine stalls when put in reverse

I have a 96 Bronco and it has several problems that are driving me nuts. I'm not sure if this is related but the fuel gauge and the rear window stopped working somewhere about the same time. It got to the point that the engine would spit and spudder when I started it. It almost sounded like a engine vapor locking when you cut it off and it keeps on running. Sometimes it will start right up and go but sometimes it will do this several times and you have to cut it off and restart it several times before it goes.

Sometimes while going down the highway it will start to lose power and sometimes it will pick back up but often you have to pull over and shut it off then restart it and it goes alright until the next time. I thought it was out of fuel but when I tried to put fuel in it I could only get 8 gals in it so it had plenty of gas in it. I got a new fuel filter and replaced the old one but it still does the same thing. I ran fuel system cleaner through it also but that didn't help either.

That is bad enough but every time I put the truck in reverse it does the same thing. I can feel it losing power and if I can shift it to neutral fast enough and rev the engine a little I can keep it from shutting off but most times it just stalls and I have to restart it sooner or later it will clear up and go.

Like I said I don't know if all these things are related or all these things just stopped at the same time.

yo mx,

WELCOME!

Can you get it scanned for Codes for free @ local parts store?

If so, post Code(s) found.

Don't buy parts yet

Without a Code to help narrow down some component or ckt testing; we can follow this 94 PCED ;

Stalls After Start

http://www.thedieselstop.com/faq/9497faq/maint/vra/vra02008.htm#vra02chart3

a Vacuum leak test Acronyms & gauge pic http://broncozone.com/topic/23994-90-58l-getting-continuous-code-33-and-running-code-44/

see my post #20

Then look @

Driveability — Performance While Driving Concerns

http://www.thedieselstop.com/faq/9497faq/maint/vra/vra02005.htm

Stalls/Quits Idle 607400 3

(607000) Acceleration 607500 9

Cruise 607600 9

Deceleration 607700 8

For some tests; 96 Bronco-F-Series Workshop Manual (PARTIAL) by Ford via;

http://www.diesel-dave.com/vehic/manual/stj/stjleft.htm

Fuel Level in Section 13-01:

Instrument Cluster, Conventional

http://www.diesel-dave.com/vehic/manual/stj/stjsd10l.htm

Fuel Gauge Testing & Connector Pin-Outs in 92-96 Bronco; Sender Range: Full = 160 Ohms; Empty = 16 Ohms; "... gauge that pegs past full indicates an open circuit (broken wire; unplugged connector; corroded terminal; burned sender) on the Y/W wire. gauge that pegs past empty indicates a short to ground (pinched to the frame, body, or dash supports) on the Y/W wire, OR a sunk float. gauge anywhere in between that doesn't move indicates an open circuit (blown fuse; corroded terminal) on the power (battery) side of the gauge OR a bad instrument cluster ground at C251 pin 9. The terminals of C251 (& C250) are known to corrode & lose contact. Polish both the connector pins AND the film circuit pads with brown paper or a pink eraser. The larger version of C441(WPT454) was used until 93. The level sender can usually be disassembled & repaired by bending the wiper arm inside the plastic housing to apply slightly more force..."

Source: by Steve @ http://www.supermotors.net/registry/media/744437

EXCERPTS;

Sender Range: 160 (full) - 16 (empty) Ohms

A gauge that pegs past full indicates an open circuit on the Y/W wire (broken wire; unplugged connector; corroded terminal; varnished sender).

A gauge that pegs past empty indicates a short to ground on the Y/W wire (pinched to the frame, body, or dash supports), OR a sunken float.

A gauge anywhere in between that doesn't move indicates an open circuit (blown fuse; corroded terminal) on the power (battery) side of the gauge OR a bad instrument cluster ground at C251 pin 9 (both of which would affect MORE of the cluster than strictly the fuel level gauge).

The terminals of C251 (& C250) are known to corrode & lose contact (open). Polish both the connector pins AND the film circuit pads with brown paper or a pink eraser.

The larger/older version of C441(WPT454) was used until '93.

The level sender can usually be disassembled & repaired by bending the wiper arm inside the plastic housing to apply slightly more force. See the other photos in this album.

For more info, see these albums' captions:

. -Bronco ONLY

READ MORE

Testing in a 96; from 96 EVTM; "...With the sending unit float arm in the empty stop position, resistance should be 15 ohms (below E). With the sending unit float arm in the full stop position, resistance should be 160 ohms (above F). The fuel gauge should read empty at 22.5 ohms and full at 145 ohms..."

Source: by miesk5

96 Bronco Fuel Lever Sender Wiring Diagrams; scroll to last;

http://www.revbase.com/BBBMotor/Wd/DownloadPdf?id=7201

also;

Wiring Diagrams in 86-current and TSBs for 80 - Current by Ford via BBBMotor @ http://www.revbase.com/BBBMotor/Wd

===

Tailgate Window Troubleshooting Synopsis; "...The tail gate circuit is pretty easy to resolve with a meter. Attached is a diagram of the circuit. Note that there are two fuses which you may have already found out. One powers the dash switch which is powered only when the key is in RUN or ACC. The other powers the tail gate switch and that line is hot at all times. If the motor is definitely good, (which can be verified by using a set of jumper leads directly to the motor connector). Once it is verified that the motor works then the common problems are: 1. The Latch Safety switch in the left side latch, This is often a problem when the tail gate fails from both switches.(you can pull the connector and jumper it out, which many people leave permanently jumpers out). The problem can be as easy as the latch needs adjustment. So if the jumper makes it work then either leave it jumped, adjust the latching stud for a tighter fit, or replace the latch switch if testing indicates it is bad. The function of the switch is to make sure the tail gate is latched before putting the window up. I like it bypassed because it makes it easy to get the window out of the way when working inside the tail gate. I think I'm smart enough to put the window back down before closing the tail gate . The only suggestion if leaving it jumped is to support the window if it is in the up position with the tail gate down. Else it could be broken by someone leaning on it. 2. The ground return for the tail gate switch uses the same two lines the dash switch does, (the grounding point is under the dash. The dash switch changes the function of the two leads running to the tail gate window motor by grounding one and putting 12V on the other. The tail gate switch uses the two leads for the ground connection, (it requires the dash switch to be in the neutral position in order to work). Depending on the year of the truck there are 2 or 3 connectors involved that often get corroded, sometimes to the point that the wires break off the connector. In your truck, there is on connector behind the left tail light, the next common failing connector is the one on the left side of the rear frame crossover member, (it is gray, if you can still see the color, and just under and behind the bumper). So to make it short, if you can operate the motor with a set of jumper leads and the window goes up and down that way, then the problem is a connection or the Latch Safety Switch. If you can't get the tail gate open to work on it, crawl in the back and remove the tail gate panel and find the motor leads attached along the bottom edge of the opening. Disconnect them and use a long set of leads or another battery in the back with you to test the motor. Once the window is down you can open the gate to make it more comfortable to work on the problem. In the diagram you will see a black with white striped wire that goes to the tail gate key switch, you should have 12V there at all times. To get at it, you will need the window in the up position. The other two leads, (with the dash switch in the center position) should indicate that they are grounded when doing a continuity check of them). You can also check the entire path from dash switch to the tail gate key switch by using a meter and probing the wires the purple with light green stripe and the dark green with light green stripe. Have someone (with the key in RUN or ACC) moving the Dash switch from UP to Down while you check those leads for 12V. If you don't get 12V then the problem is in a connector between the two switches or a broken wire (a broken wire would most likely be where they transition between the body and tail gate due to constant flexing). The procedure would be; 12V missing on one of the wires, move back to the connector behind the tail light (missing there), move to the connector on the cross member (missing there) move back to the connectors in front, until you find where you have 12V on the line you are probing. Once you find 12V the problem is between the last point probed and where you find 12V..."

Source: by Seabronc (Rosie, Fred W) at Ford Bronco Zone Forums

http://broncozone.com/topic/7671-tailgate-window-switch/

Wiring Diagram in a 96 @ http://www.revbase.com/BBBMotor/Wd/DownloadPdf?id=53224

miesk5 said:

yo mx,

WELCOME!

Can you get it scanned for Codes for free @ local parts store?

If so, post Code(s) found.

Don't buy parts yet

Without a Code to help narrow down some component or ckt testing; we can follow this 94 PCED ;

Stalls After Start

http://www.thedieselstop.com/faq/9497faq/maint/vra/vra02008.htm#vra02chart3

a Vacuum leak test Acronyms & gauge pic http://broncozone.com/topic/23994-90-58l-getting-continuous-code-33-and-running-code-44/

see my post #20

Then look @

Driveability — Performance While Driving Concerns

http://www.thedieselstop.com/faq/9497faq/maint/vra/vra02005.htm

Stalls/Quits Idle 607400 3

(607000) Acceleration 607500 9

Cruise 607600 9

Deceleration 607700 8

For some tests; 96 Bronco-F-Series Workshop Manual (PARTIAL) by Ford via;

http://www.diesel-dave.com/vehic/manual/stj/stjleft.htm

Fuel Level in Section 13-01:

Instrument Cluster, Conventional

http://www.diesel-dave.com/vehic/manual/stj/stjsd10l.htm

Fuel Gauge Testing & Connector Pin-Outs in 92-96 Bronco; Sender Range: Full = 160 Ohms; Empty = 16 Ohms; "... gauge that pegs past full indicates an open circuit (broken wire; unplugged connector; corroded terminal; burned sender) on the Y/W wire. gauge that pegs past empty indicates a short to ground (pinched to the frame, body, or dash supports) on the Y/W wire, OR a sunk float. gauge anywhere in between that doesn't move indicates an open circuit (blown fuse; corroded terminal) on the power (battery) side of the gauge OR a bad instrument cluster ground at C251 pin 9. The terminals of C251 (& C250) are known to corrode & lose contact. Polish both the connector pins AND the film circuit pads with brown paper or a pink eraser. The larger version of C441(WPT454) was used until 93. The level sender can usually be disassembled & repaired by bending the wiper arm inside the plastic housing to apply slightly more force..."

Source: by Steve @ http://www.supermotors.net/registry/media/744437

EXCERPTS;

Sender Range: 160 (full) - 16 (empty) Ohms

A gauge that pegs past full indicates an open circuit on the Y/W wire (broken wire; unplugged connector; corroded terminal; varnished sender).

A gauge that pegs past empty indicates a short to ground on the Y/W wire (pinched to the frame, body, or dash supports), OR a sunken float.

A gauge anywhere in between that doesn't move indicates an open circuit (blown fuse; corroded terminal) on the power (battery) side of the gauge OR a bad instrument cluster ground at C251 pin 9 (both of which would affect MORE of the cluster than strictly the fuel level gauge).

The terminals of C251 (& C250) are known to corrode & lose contact (open). Polish both the connector pins AND the film circuit pads with brown paper or a pink eraser.

The larger/older version of C441(WPT454) was used until '93.

The level sender can usually be disassembled & repaired by bending the wiper arm inside the plastic housing to apply slightly more force. See the other photos in this album.

For more info, see these albums' captions:

. -Bronco ONLY

READ MORE

Testing in a 96; from 96 EVTM; "...With the sending unit float arm in the empty stop position, resistance should be 15 ohms (below E). With the sending unit float arm in the full stop position, resistance should be 160 ohms (above F). The fuel gauge should read empty at 22.5 ohms and full at 145 ohms..."

Source: by miesk5

96 Bronco Fuel Lever Sender Wiring Diagrams; scroll to last;

http://www.revbase.com/BBBMotor/Wd/DownloadPdf?id=7201

also;

Wiring Diagrams in 86-current and TSBs for 80 - Current by Ford via BBBMotor @ http://www.revbase.com/BBBMotor/Wd

===

Tailgate Window Troubleshooting Synopsis; "...The tail gate circuit is pretty easy to resolve with a meter. Attached is a diagram of the circuit. Note that there are two fuses which you may have already found out. One powers the dash switch which is powered only when the key is in RUN or ACC. The other powers the tail gate switch and that line is hot at all times. If the motor is definitely good, (which can be verified by using a set of jumper leads directly to the motor connector). Once it is verified that the motor works then the common problems are: 1. The Latch Safety switch in the left side latch, This is often a problem when the tail gate fails from both switches.(you can pull the connector and jumper it out, which many people leave permanently jumpers out). The problem can be as easy as the latch needs adjustment. So if the jumper makes it work then either leave it jumped, adjust the latching stud for a tighter fit, or replace the latch switch if testing indicates it is bad. The function of the switch is to make sure the tail gate is latched before putting the window up. I like it bypassed because it makes it easy to get the window out of the way when working inside the tail gate. I think I'm smart enough to put the window back down before closing the tail gate . The only suggestion if leaving it jumped is to support the window if it is in the up position with the tail gate down. Else it could be broken by someone leaning on it. 2. The ground return for the tail gate switch uses the same two lines the dash switch does, (the grounding point is under the dash. The dash switch changes the function of the two leads running to the tail gate window motor by grounding one and putting 12V on the other. The tail gate switch uses the two leads for the ground connection, (it requires the dash switch to be in the neutral position in order to work). Depending on the year of the truck there are 2 or 3 connectors involved that often get corroded, sometimes to the point that the wires break off the connector. In your truck, there is on connector behind the left tail light, the next common failing connector is the one on the left side of the rear frame crossover member, (it is gray, if you can still see the color, and just under and behind the bumper). So to make it short, if you can operate the motor with a set of jumper leads and the window goes up and down that way, then the problem is a connection or the Latch Safety Switch. If you can't get the tail gate open to work on it, crawl in the back and remove the tail gate panel and find the motor leads attached along the bottom edge of the opening. Disconnect them and use a long set of leads or another battery in the back with you to test the motor. Once the window is down you can open the gate to make it more comfortable to work on the problem. In the diagram you will see a black with white striped wire that goes to the tail gate key switch, you should have 12V there at all times. To get at it, you will need the window in the up position. The other two leads, (with the dash switch in the center position) should indicate that they are grounded when doing a continuity check of them). You can also check the entire path from dash switch to the tail gate key switch by using a meter and probing the wires the purple with light green stripe and the dark green with light green stripe. Have someone (with the key in RUN or ACC) moving the Dash switch from UP to Down while you check those leads for 12V. If you don't get 12V then the problem is in a connector between the two switches or a broken wire (a broken wire would most likely be where they transition between the body and tail gate due to constant flexing). The procedure would be; 12V missing on one of the wires, move back to the connector behind the tail light (missing there), move to the connector on the cross member (missing there) move back to the connectors in front, until you find where you have 12V on the line you are probing. Once you find 12V the problem is between the last point probed and where you find 12V..."

Source: by Seabronc (Rosie, Fred W) at Ford Bronco Zone Forums

http://broncozone.com/topic/7671-tailgate-window-switch/

Wiring Diagram in a 96 @ http://www.revbase.com/BBBMotor/Wd/DownloadPdf?id=53224

Click to expand...

Well that will give me something to do for a few days /emoticons/[email protected] 2x" width="20" height="20" /> 

Hopefully I can get the time to go over this list over the weekend and see what I come up with. I've been trying to get a friend to come by with his scanner to check it but he has been real busy and is having a hard time finding time. I don't like driving it because I never know when it shuts down if it is going to start up again. so far it has always started eventually but I'm a ways out in the boonies and I hate walking. If he don't show up in a day or two I'll bite the bullet and make the trip to town. 

Thanks for all the links they should be real helpful.

OK, I'm back again.......sorry it took me so long. I got tired of waiting for my buddy so I had to find a way to get the codes read another way. I went by a couple parts stores and every time I got there the only person that could operate their machine was out for some reason. I made a few bucks selling some scrap I had laying around and I went by another part store and bought a cheap reader that was on sale from $79.95 to $39.95. They said it would read anything from 96 on up so I went ahead and got it.

The directions that came with it were lacking and the operators manual said there was a CD that was supposed to be in the box was not there. It was supposed to be a little more detailed on how to operate it and have more code information that was not in the booklet. 

Anyway.....here is what I came up with. There were 7 codes that were entered and here is the list. 

P0133

P0401

P1131

P1151

P0385

P0171

P0174

A couple of those codes were not in the booklet the P1131/ P1151 because they are ford codes and the booklet said they would be on the CD or I would have to find out what they were from ford.

A couple were lean conditions on the left and right banks and low flow to the EGR I think it said. I don't have the booklet in front of me and what I'm thinking is that these may have been from before I changed the fuel filter. It was pretty nasty when I changed it and once I did it seemed to run a little better at least on the highway. Just before I changed the filter it almost stopped completely on the highway and has not done that since. I was thinking about clearing these codes and drive it a little to see if they come back.

It still sometimes,........ well most of the time it will when you start it (cold or warm start) it will stumble for a time and then go on and run. Other times you will have to shut it off and restart it several times before it will go. Once it starts sometimes it will run ok and others it will lose power a little then clear up. It still will not back up. If I put it in reverse it will stumble just like it does on start up and cut off which is a real pain to have to deal with.

I have always felt there were several different problems that I am dealing with not counting the window and fuel gauge problem. I think they are related to the switch on the dash because I know the switch is bad because I broke it trying to get it to work the last time I fooled with it. For right now I'm not worried about the window or the fuel gauge I can deal with them later once the weather get better but I would like to get it so I can drive it without fear of getting stranded somewhere in the boonies.

Thanks for your help. Oh and I haven't cleared those codes yet I'll wait to see what you have to say first.

yo mx,

I'll list the DTCs that I have info on now and try to find pin-pointtests later; but my 96 Bronco EVTM that had the testing didn't work on WIN 8 or 8.1 PCs or laptops, so I gave it away.

DTC P0133 - HO2S Sensor Circuit Slow Response (HO2S-11) The HO2S monitor checks the HO2S sensor frequency and amplitude. If during testing, the frequency and amplitude were to fall below a calibrated limit, the code will set; Possible Causes: Electrical: · Shorted/open wiring · PCM Induction System: · MAF sensor (On 4-cylinder engines, if P0133 is present, this could be caused by a MAF issue - on 6- and 8-cylinder engines, this could only be a MAF issue if P0133 and P0153 are both present) · Inlet air leaks (unmetered air) Fuel Concerns: · Poor fuel quality Base Engine: · Exhaust leaks (upstream or near HO2S) HO2S Concerns: · Contaminated HO2S sensor (contamination from the use of silicone-based cleaners and sealants, leaded fuel, excessive oil consumption - Deteriorating HO2S sensor; OBD II Response Rate Monitor: The OBD II Response Rate Monitor (P0133/P0153) is only run at vehicle speeds between approximately 50-95 km/h (30-60 mph), during steady-state conditions. The test lasts approximately 6 seconds. Therefore, P0133/P0153 cannot be diagnosed at idle in the repair bay...Most replace the O2 Sensor; but ck for wiring/connector/harness damage and other likely and no $ parts replacement checks 1st; incl testing the sensor ckt; fuses, heater ckt, etc. Fords naming convention is that bank one is the same bank as where the number one cylinder is sensor one is before the cat sensor two is after the cat.

Source: by miesk5

DTC P0133 - HO2S Sensor Circuit Slow Response (HO2S-11); "... The HEGO Monitor checks the HO2S Sensor frequency and amplitude. If during testing the frequency and amplitude were to fall below a calibrated limit, the test will fail. Contaminated HO2S sensor. Exhaust leaks. Shorted /open wiring. Improper fueling. MAF sensor. Deteriorating HO2S sensor. Inlet air leaks. Access HO2S test results from the Generic OBD-II menu to verify DTC..."

Source: by slingblade

================

DTC P0401 - EGR Flow Insufficient Detected ; "...The EGR system is monitored during steady state driving conditions while the EGR is commanded on. The test fails when the signal from the DPF EGR sensor indicates that EGR flow is less than the desired minimum. Vacuum supply; EGR valve stuck closed; EGR valve leaks vacuum; EGR flow path restricted EGRVR circuit shorted to PWR VREF open to DPFE sensor; DPFE sensor downstream hose off or plugged EGRVR circuit; open to PCM VPWR open to EGRVR solenoid DPFE sensor hoses both off DPFE sensor hoses reversed Damaged EGR orifice tube Damaged EGRVR solenoid Damaged PCM Perform KOER self-test and look for DTC P1408 as an indication of a hard fault. If P1408 is not present, look for contamination, restrictions, leaks, and intermittents..."

Source: by slingblade;;

DTC P0401 EGR Flow Insufficient Detected Possible Causes; "...DTC P0401 is for exhaust gas recirculation (EGR) insufficient flow detected. This most likely means one or more of the following has happened: The EGR valve may not be opening due to a lack of vacuum; There is a blockage in the EGR (most likely carbon buildup); The DPFE sensor is faulty and needs to be replaced; The EGR valve is faulty. In fixing this code, it is quite common for people to just replace the EGR valve only to have the OBD code return. However, just like many other DTCs, the problem is not always obvious and the EGR valve is not always the culprit..." READ MUCH MORE

Source: by Gateway Clean Air Program dnr.mo.gov

======

DTC P0171, P0172, P0174 & P0175, P1130, P1131, P1132, P1150, P1151, P1152; 181, 189 (Fuel system lean, Bank 1 or 2), 179, 188 (Fuel system rich, Bank 1 or 2); 171, 172, 173 (HO2S11 lack of switching, Bank 1); 175, 176, 177 (HO2S21 lack of switching, Bank 2); 184, 185 (MAF higher/lower than expected); 186, 187 (Injector pulse width higher/lower than expected) & Possible Causes in MAF Contamination TSB 98-23-10 for 94-96; NOTE: THE FOLLOWING PROCEDURE MAY ALSO BE USED TO DIAGNOSE VEHICLES THAT DO NOT HAVE FUEL SYSTEM/HO2S SENSOR DTCs. Symptoms: Lack of Power, Spark Knock/Detonation, Buck/**** Hesitation/Surge on Acceleration

MAF Contamination TSB 98-23-10 for 94-96

Source: by Ford via miesk5 at cc ISSUE: This TSB article is a diagnostic procedure to address vehicles that exhibit lean driveability symptoms and may or may not have any Diagnostic Trouble Codes (DTCs) stored in memory.

ACTION: Follow the diagnostic procedures described in the following Service Tip. The revised diagnostic procedure is a more accurate means of diagnosing the symptoms.

SERVICE TIP MASS AIR FLOW (MAF) DISCUSSION

MAF sensors can get contaminated from a variety of sources: dirt, oil, silicon, spider webs, potting compound from the sensor itself, etc. When a MAF sensor gets contaminated, it skews the transfer function such that the sensor over-estimates air flow at idle (causes the fuel system to go rich) and under-estimates air flow at high air flows (causes fuel system to go lean). This means Long Term Fuel Trims will learn lean (negative) corrections at idle and learn rich (positive) corrections at higher air flows.

If vehicle is driven at Wide Open Throttle (WOT) or high loads, the fuel system normally goes open loop rich to provide maximum power. If the MAF sensor is contaminated, the fuel system will actually be lean because of under-estimated air flow. During open loop fuel operation, the vehicle applies Long Term Fuel Trim corrections that have been learned during closed loop operation. These corrections are often lean corrections learned at lower air flows. This combination of under-estimated air flow and lean fuel trim corrections can result in spark knock/detonation and lack of power concerns at WOT and high loads.

One of the indicators for diagnosing this condition is barometric pressure. Barometric pressure (BARO) is inferred by the Powertrain Control Module (PCM) software at part throttle and WOT (there is no actual BARO sensor on MAF-equipped vehicles, except for the 3.8L Supercharged engine). At high air flows, a contaminated MAF sensor will under-estimate air flow coming into the engine, hence the PCM infers that the vehicle is operating at a higher altitude. The BARO reading is stored in Keep Alive Memory (KAM) after it is updated. Other indicators are Long Term Fuel Trim and MAF voltage at idle.

NOTE: THE FOLLOWING PROCEDURE MAY ALSO BE USED TO DIAGNOSE VEHICLES THAT DO NOT HAVE FUEL SYSTEM/HO2S SENSOR DTCs.

Symptoms

Lack of Power

Spark Knock/Detonation

Buck/****

Hesitation/Surge on Acceleration

Malfunction Indicator Lamp (MIL) Illuminated - DTCs P0171, P0172, P0174, P0175 may be stored in memory

OBDII DTCs

P0171, P0174 (Fuel system lean, Bank 1 or 2)

P0172, P0175 (Fuel system rich, Bank 1 or 2)

P1130, P1131, P1132, (HO2S11 lack of switching, Bank 1)

P1150, P1151, P1152, (HO2S21 lack of switching, Bank 2)

OBDI DTCs

181, 189 (Fuel system lean, Bank 1 or 2)

179, 188 (Fuel system rich, Bank 1 or 2)

171, 172, 173 (HO2S11 lack of switching, Bank 1)

175, 176, 177 (HO2S21 lack of switching, Bank 2)

184, 185 (MAF higher/lower than expected)

186, 187 (Injector pulse width higher/lower than expected)

NOTE: DO NOT DISCONNECT THE BATTERY. IT WILL ERASE KEEP ALIVE MEMORY AND RESET LONG TERM FUEL TRIM AND BARO TO THEIR STARTING/BASE VALUES. THE BARO PARAMETER IDENTIFICATION DISPLAY (PID) IS USED FOR THIS DIAGNOSTIC PROCEDURE. ALL OBDII APPLICATIONS HAVE THIS PID AVAILABLE. THERE ARE SOME OBDI VEHICLES THAT DO NOT HAVE THE BARO PID, FOR THESE VEHICLES OMIT THE BARO CHECK AND REFER ONLY TO STEPS 2, 3, AND 4 IN THE DIAGNOSTIC PROCEDURE.

1. Look at the BARO PID. Refer to the Barometric Pressure Reference Chart in this article. At sea level, BARO should read about 159 Hz (29.91 in. Hg). As a reference, Denver, Colorado at 1524 meters (5000 ft.) altitude should be about 144 Hz (24.88 in. Hg.). Normal learned BARO variability is up to ±6 Hz (±2 in. Hg.). If BARO indicates a higher altitude than you are at (7 or more Hz lower than expected), you may have MAF contamination. If available, Service Bay Diagnostic System (SBDS) has a Manifold Absolute Pressure (MAP) sensor that can be used as a barometric pressure reference. Use "MAP/BARO" test under "Powertrain," "Testers and Meters." Ignore the hookup screen. Connect GP2 to the reference MAP on the following screen.

NOTE: REMEMBER THAT MOST WEATHER SERVICES REPORT A LOCAL BAROMETRIC PRESSURE THAT HAS BEEN CORRECTED TO SEA LEVEL. THE BARO PID, ON THE OTHER HAND, REPORTS THE ACTUAL BAROMETRIC PRESSURE FOR THE ALTITUDE THE VEHICLE IS BEING OPERATED IN. LOCAL WEATHER CONDITIONS (HIGH AND LOW PRESSURE AREAS) WILL CHANGE THE LOCAL BAROMETRIC PRESSURE BY SEVERAL INCHES OF MERCURY (±3 Hz, ±1 in. Hg.).

NOTE: BARO IS UPDATED ONLY WHEN THE VEHICLE IS AT HIGH THROTTLE OPENINGS. THEREFORE, A VEHICLE WHICH IS DRIVEN DOWN FROM A HIGHER ALTITUDE MAY NOT HAVE HAD AN OPPORTUNITY TO UPDATE THE BARO VALUE IN KAM. IF YOU ARE NOT CONFIDENT THAT BARO HAS BEEN UPDATED, PERFORM THREE OR FOUR HEAVY, SUSTAINED ACCELERATIONS AT GREATER THAN HALF-THROTTLE TO ALLOW BARO TO UPDATE.

2. On a fully warmed up engine, look at Long Term Fuel Trim at idle, in Neutral, A/C off, (LONGFT1 and/or LONGFT2 PIDs). If it is more negative than -12%, the fuel system has learned lean corrections which may be due to the MAF sensor over-estimating air flow at idle. Note that both Banks 1 and 2 will exhibit negative corrections for 2-bank system. If only one bank of a 2-bank system has negative corrections, the MAF sensor is probably not contaminated.

3. On a fully warmed up engine, look at MAF voltage at idle, in Neutral, A/C off (MAF V PID). If it's 30% greater than the nominal MAF V voltage listed in the Powertrain Control/Emissions Diagnosis (PC/ED) Diagnostic Value Reference Charts for your vehicle, or greater than 1.1 volts as a rough guide, the MAF sensor is over-estimating air flow at idle.

4. If at least two of the previous three steps are true, proceed to disconnect the MAF sensor connector. This puts the vehicle into Failure Mode and Effects Management (FMEM). In FMEM mode, air flow is inferred by using rpm and throttle position instead of reading the MAF sensor. (In addition, the BARO value is reset to a base/unlearned value.) If the lean driveability symptoms go away, the MAF sensor is probably contaminated and should be replaced. If the lean driveability symptoms do not go away, go to the PC/ED Service Manual for the appropriate diagnostics.

NOTE:

DUE TO INCREASINGLY STRINGENT EMISSION/OBDII REQUIREMENTS, IT IS POSSIBLE FOR SOME VEHICLES WITH MAF SENSOR CONTAMINATION TO SET FUEL SYSTEM DTCs AND ILLUMINATE THE MIL WITH NO DRIVEABILITY CONCERNS. DISCONNECTING THE MAF ON THESE VEHICLES WILL, THEREFORE, PRODUCE NO IMPROVEMENTS IN DRIVEABILITY. IN THESE CASES, IF THE BARO, LONGFT1, LONGFT2, AND MAF V PIDs INDICATE THAT THE MAF IS CONTAMINATED, PROCEED TO REPLACE THE MAF SENSOR.

After replacing the MAF sensor, disconnect the vehicle battery (5 minutes, minimum) to reset KAM, or on newer vehicles, use the "KAM Reset" feature on the New Generation Star (NGS) Tester and verify that the lean driveability symptoms are gone.

OTHER APPLICABLE ARTICLES: NONE

WARRANTY STATUS: INFORMATION ONLY

OASIS CODES: 206000, 610000, 610500, 610600, 610700, 611000, 611500, 612000, 612500, 614000, 614500, 614600, 698298

===============

Diagnostic Trouble Code P0385 indicates a Misfire Detection Sensor Ckt Failure

Misfire Detection (MD) Sensor is located on the front of the timing chain cover, and is a two wire sensor.

Here is a pic 

http://www.supermotors.org/getfile/71337/fullsize/CPS.JPG

dead in the middle of this photo - black connector

Is MD sensor disconnected?

However that code could also be generated because of a misfire. Also check for any crossfiring plug wires and make sure that the spark plugs are in good condition. The quick way to check for crossfiring plug wires is to mist the plug wires lightly with water when it is dark and watch for sparks

from 96 Bronco EVTM

The misfire sensor is an electromagnetic inductance coil similar in operation to a camshaft or crankshaft position sensor. A four-point stator, or pulse ring, located behind the crankshaft damper generates an electrical impulse in the sensor at each 90 degrees of rotation. The powertrain control module (PCM) (12A650) monitors the sensor pulses and flags any misfire events. When a specified number of misfires occur within a certain time frame, the powertrain control module will alert the driver to the condition by turning on the malfunction indicator light (MIL).

Note:

Misfire sensor is not required on 49 State/Canada 7.5L engine. It is required on a 7.5L California engine

PIN-POINT TEST

Distributor Ignition

Key On Engine Off:

Key On Engine Running:

«DK1»

Continuous Memory:

«DK1»

Diagnostic Trouble Code (DTC) P0385 indicates that Self-Test has detected a Misfire Detection (MD) Sensor circuit failure.

Possible causes:

MD circuit open.

MD circuit shorted to GND.

MD circuit shorted to PWR.

SIG RTN open

Damaged MD Sensor.

Damaged PCM.

Start engine.

Will the engine start?

Yes GO to «DK2».

http://fullsizebronco.com/forum/attachment.php?attachmentid=18087&stc=1&d=1315834507

No - DTC P0385 is not the cause of the No Start. GO to «Section 4A», Symptom Flowchart

See attachment

DK2 CLEAR AND ATTEMPT TO RE-GENERATE DTC P0385

Complete PCM Reset to clear DTCs (refer to Section 2A, «Powertrain Control Module (PCM) Reset»).

Start engine.

Increase rpm to greater than 1500 rpm for 10 seconds. Repeat two times.

Key off.

Retrieve all Continuous Memory DTCs.

Is DTC P0385 present?

Yes GO to «DK5».

No The fault that produced DTC P0385 is intermittent. GO to Pinpoint Test Step «Z50»

Z50 step should be used with the Intermittent Ignition Analyzer (Part No. Rotunda 007-00075). If this analyzer is not available, or this is a coil on plug application, return to «Z1» and choose another procedure.

DK5

Key off.

MD sensor vehicle harness connector disconnected.

Disconnect PCM. Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary.

Install breakout box, leave PCM disconnected.

*** miesk5 Note; as I mentioned in another thread here; In place of the breakout box, go to the EEC pin instead ****

BOB pins are same as PCM pins; use str8 pin to probe wires w/meter lead attached.

See PCM Connector pin diagram

http://web.archive.org/web/20130513041508im_/http://oldfuelinjection.com/images/eec05.gif

Pin Number Circuit Circuit Function

1 315 (P/O) PCM to Transmission Shift Solenoid No. 2

2 658 (P/LG) PCM to Check Engine Indicator Lamp

3 � Not Used

4 � Not Used

5 � Not Used

6 651 (BK/Y) Dedicated Ground

7 � Not Used

8 � Not Used

9 � Not Used

10 � Not Used

11 � Not Used

12 � Not Used

13 107 (P) PCM Flash EEPROM Power Supply

14 784 (LB/BK) 4x4 Low Range Switch to PCM Indicator Lamp

15 915 (PK/LB) J1850 Bus Negative/Data Negative (Return) to PCM

16 914 (T/O) J1850 Bus Positive/Data Positive

17 � Not Used

18 � Not Used

19 � Not Used

20 � Not Used

21 � Not Used

22 � Not Used

23 259 (O/R) Dedicated Ground to TFI Module

24 570 (BK/W) Dedicated Ground � PCM

25 875 (BK/LB) Ground Logic Module

26 � Not Used

27 237 (O/Y) PCM to Transmission Shift Solenoid No. 1

28 � Not Used

29 224 (T/W) Transmission Overdrive Cancel Switch to PCM

30 � Not Used

31 � Not Used

32 � Not Used

33 676 (PK/O) Vehicle Speed Sensor � Negative (Return) to PCM

34 � Not Used

35 392 (P/LG) Heated Exhaust Gas Oxygen Sensor No. 3 to PCM

36 968 (T/LB) Mass Airflow Return

37 923 (O/BK) Transmission Oil Temperature to PCM

38 354 (LG/R) Engine Coolant Temperature Sensor to PCM

39 743 (GY) Air Charge Temperature Sensor to PCM

40 238 (DG/Y) Fuel Pump Monitor to PCM/Fuel Pump Relay to Safety Switch

41 198 (DG/O) A/C Pressure Switch to Control Relay

42 � Not Used

43 � Not Used

44 200 (BR) PCM to Air Management No. 2 (Was TAD)

45 � Not Used

46 � Not Used

47 360 (BR/PK) PCM to Electronic Vacuum Regulator � Constant Current

48 382 (Y/BK) PCM to Test Connector No. 2

49 395 (GY/O) Profile Ignition Pickup to PCM

50 929 (PK) PCM to Spark Angle Pulse Width/Spark Output

51 570 (BK/W) Dedicated Ground � PCM

52 � Not Used

53 924 (BR/O) PCM to Transmission Coast Clutch Solenoid

54 480 (P/Y) PCM to Transmission Converter Clutch Control

55 37 (Y) Battery to Load

56 191 (LG/BK) PCM Top Vapor Management Valve � Constant Current

57 310 (Y/R) Knock Sensor No. 1 to PCM

58 679 (GY/BK) Vehicle Speed Sensor � Positive to PCM

59 917 (DG/LG) Misfire Detection Sensor � Feed

60 74 (GY/LB) Heated Exhaust Gas Oxygen Sensor No. 1 to PCM

61 � Not Used

62 � Not Used

63 � Not Used

64 199 (LB/Y) Manual Lever Position Sensor to PCM

65 352 (BR/LG) Delta Exhaust Pressure Transducer to PCM

66 � Not Used

67 � Not Used

68 � Not Used

69 � Not Used

70 190 (W/O) PCM to Air Management No. 1 (Was TAB)

71 361 ® Power Output from PCM Relay

72 561 (T/R) PCM to Fuel Injector No. 7 Cylinder

73 559 (T/BK) PCM to Fuel Injector No. 5 Cylinder

74 557 (W) PCM to Fuel Injector No. 3 Cylinder

75 555 (T) PCM to Fuel Injector No. 1 Cylinder or Bank No. 1

76 570 (BK/W) Dedicated Ground � PCM

77 570 (BK/W) Dedicated Ground � PCM

78 � Not Used

79 911 (W/LG) PCM to Output Circuit Indicator Lamp/Overdrive Cancel Indicator

80 926 (LG/O) PCM to Fuel Pump Relay Control

81 925 (W/Y) PCM to Electronic Pressure Control No. 1

82 � Not Used

83 264 (W/LB) PCM to Idle Speed Control Motor No. 1

84 136 (DB/Y) Output Shaft Speed to PCM

85 � Not Used

86 � Not Used

87 94 (R/BK) Heated Exhaust Gas Oxygen Sensor No. 2 to PCM

88 967 (LB/R) Mass Air Flow Sensor to PCM

89 355 (GY/W) Throttle Position Sensor to PCM/Diesel Fuel Injector Pump Lever Sensor

90 351 (BR/W) Power to Engine Sensors

91 359 (GY/R) Sensor Signal Return

92 511 (LG) Stoplamp (Brake On/Off) Switch to Stoplamps

93 387 (R/W) HEGO Sensor Heater Voltage Monitor No. 1 to PCM

94 388 (Y/LB) HEGO Sensor Heater Voltage Monitor No. 2 to PCM

95 389 (W/BK) HEGO Sensor Heater Voltage Monitor No. 3 to PCM

96 � Not Used

97 361 ® Power Output from PCM Relay

98 562 (LB) PCM to Fuel Injector No. 8 Cylinder

99 560 (LG/O) PCM to Fuel Injector No. 6 Cylinder

100 558 (BR/LB) PCM to Fuel Injector No. 4 Cylinder

101 556 (W) PCM to Fuel Injector No. 2 Cylinder or Bank No. 2

102 � Not Used

103 570 (BK/W) Dedicated Ground � PCM

104 � Not Used

Measure resistance between MD circuit at the MD vehicle harness connector and Test Pin 59 (MD) at the breakout box.

Measure resistance between misfire RTN circuit at the MD vehicle harness connector and Test Pin 6 (SIG RTN) at the breakout box.

Are resistance measurements less than 5.0 ohms?

Yes GO to «DK6».

No SERVICE open circuit. REMOVE breakout box.

RECONNECT all components. RERUN «Quick Test».

DK6 CHECK MD FOR SHORT TO POWER

Key off.

MD sensor disconnected.

Breakout box installed, PCM disconnected.

Key on, engine off.

Measure voltage between Test Pin 59 (MD) and Test Pins 51 and 103 (PWR GND) at the breakout box.

Is voltage less than 1.0 volt?

Yes GO to «DK7».

No SERVICE MD circuit for short to power. REMOVE breakout box. RECONNECT all components. RERUN «Quick Test»

DK7 CHECK MD FOR SHORT TO GND

Key off.

Breakout box installed, PCM disconnected.

MD sensor disconnected.

Measure resistance between Test Pin 59 (MD) and Test Pins 51, 103 (PWR GND) and 6 (misfire RTN).

Is each resistance greater than 10,000 ohms?

Yes GO to «DK8».

No SERVICE MD circuit for short to GND or SIG RTN. REMOVE breakout box. RECONNECT all components. RERUN «Quick Test»

DK8 CHECK FOR SHORTS IN PCM

Key off.

MD sensor disconnected.

Breakout box installed.

Connect PCM to breakout box.

Measure resistance between Test Pin 59 (MD) and Test Pins 51, 103 (PWR GND), 71, 97 (VPWR), and 6 (misfire RTN), and 23 (IGN GND) at the breakout box.

Is each resistance greater than 500 ohms?

Yes GO to «DK9».

No REPLACE PCM. REMOVE breakout box. RECONNECT all components. RERUN «Quick Test».

K9 CHECK MD SENSOR OUTPUT

Key off.

Breakout box installed, PCM connected.

Reconnect MD sensor.

DVOM on AC scale (to monitor less than 5.0 volts).

Measure voltage between Test Pin 59 (MD) and Test Pins 51 and 103 (PWR GND) at the breakout box while running engine at varying rpm.

Does AC voltage vary greater than 0.1 volt AC?

Yes REPLACE PCM. REMOVE breakout box. RECONNECT all components. RERUN «Quick Test».

No GO to «DK10».

K10 INSPECT MD SENSOR TRIGGER WHEEL

Is the MD sensor trigger wheel damaged, i.e., loose or misaligned?

Yes REPLACE or SERVICE as required. REMOVE all test equipment. RECONNECT all components. RERUN «Quick Test».

No REPLACE sensor. REMOVE breakout box. RECONNECT all components. RERUN «Quick Test».

.................

Removal1. Disconnect battery negative cable.

2. If engine is a V-8, proceed to next step. On a 4.9L engine, remove engine cooling fan and shroud. Refer to «Section 03-05».

3. Remove attaching screws and timing pointer.

4. Disconnect wiring and remove sensor.

Installation

1. Follow removal procedures in reverse order.

2. Tighten attaching screws to 8-12 N-m (75-105 lb-in).

--

"...The Misfire Detection Sensor is used with a TFI distributor system. The PIP signal generated by the distributor is not accurate enough to detect misfires. Because of this, a dedicated misfire detection sensor is used along with a crankshaft-mounted toothed wheel.

The following vehicles use the MFDS: 4.9L E and F-Series, 5.0L E, F-Series, and Explorer, 5.8L E, F-Series and Bronco, 7.5L E and F-Series

Misfire Detection Sensor Check

Misfire Detection Sensor Check Operation:

DTC P0385 (MFDS) Monitor execution continuous;

The LDR Misfire Monitor uses a low-data-rate crankshaft position signal, (i.e. one position reference signal at 10 deg BTDC for each cylinder event). Distributor ignition systems utilize a dedicated misfire detection sensor.

The PCM calculates crankshaft rotational velocity for each cylinder from this crankshaft position signal. The acceleration for each cylinder can then be calculated using successive velocity values. The changes in overall engine rpm are removed by subtracting the median engine acceleration over a complete engine cycle. The resulting deviant cylinder acceleration values are used in evaluating misfire in the “General Misfire Algorithm

Processing” section below.

On some vehicles, “profile correction” software is used to “learn” and correct for mechanical inaccuracies in crankshaft tooth spacing under de-fueled engine conditions (requires three 60 to 40 mph no-braking decels after Keep Alive Memory has been reset). These learned corrections improve the high-rpm capability of the monitor formost engines. The misfire monitor is not active until a profile has been learned..."

http://fullsizebronco.com/forum/attachment.php?attachmentid=18084&stc=1&d=1315828537

-------------------------

P1131 upstream oxygen sensor is not switching rich to lean and back as frequently as it should. This could be due to a vacuum leak, a failing oxygen sensor, or a rich fuel mixture.

Possible Causes are; high fuel pressure, low fuel pressure, restricted fuel filter, engine misfire, leaking intake manifold gasket, incorrect (stuck open or too cold) engine thermostat, low engine coolant level, restricted air filter, leaking vacuum hoses, or anything else that could affect fuel mixture

Source: by Ford via miesk5

======

DTC P0171 & P0174 Lean Troubleshooting; "...These codes commonly occur on many Ford vehicles, and are set when the powertrain control module (PCM) sees the air/fuel mixture is running too lean (too much air, not enough fuel). Unmetered air can enter the engine through a vacuum leak, a dirty airflow sensor (MAF) that is not reading airflow accurately, an EGR valve is not closing (DPFE) and is leaking exhaust into the intake manifold, an EGR valve that is allowing too much flow (because the EGR differential pressure sensor that monitors EGR flow is faulty and is under-reporting EGR flow). If the problem is not enough fuel, the underling cause may be a weak fuel pump, restricted fuel filter, leaky fuel pressure regulator or dirty fuel injectors..."

Source: by Larry C at AA1Car.com

DTC P0171 - System to Lean (Bank 1); "... The Adaptive Fuel Strategy continuously monitors fuel delivery hardware. The test fails when the adaptive fuel tables reach a rich calibrated limit. For lean and rich DTCs: Fuel system Excessive fuel pressure. Leaking/contaminated fuel injectors. Leaking fuel pressure regulator. Low fuel pressure or running out of fuel. Vapor recovery system. Induction system: Air leaks after the MAF. Vacuum Leaks. PCV system. Improperly seated engine oil dipstick. EGR system: Leaking gasket. Stuck EGR valve. Leaking diaphragm or EVR. Base Engine: Oil overfill. Cam timing. Cylinder compression. Exhaust leaks before or near the HO2Ss ..."

Source: by slingblade

DTC P0171, P0172, P0174 & P0175, P1130, P1131, P1132, P1150, P1151, P1152; 181, 189 (Fuel system lean, Bank 1 or 2), 179, 188 (Fuel system rich, Bank 1 or 2); 171, 172, 173 (HO2S11 lack of switching, Bank 1); 175, 176, 177 (HO2S21 lack of switching, Bank 2); 184, 185 (MAF higher/lower than expected); 186, 187 (Injector pulse width higher/lower than expected) & Possible Causes in MAF Contamination TSB 98-23-10 for 94-96; NOTE: THE FOLLOWING PROCEDURE MAY ALSO BE USED TO DIAGNOSE VEHICLES THAT DO NOT HAVE FUEL SYSTEM/HO2S SENSOR DTCs. Symptoms: Lack of Power, Spark Knock/Detonation, Buck/**** Hesitation/Surge on Acceleration

MAF Contamination TSB 98-23-10 for 94-96

Source: by Ford via miesk5 at cc ISSUE: This TSB article is a diagnostic procedure to address vehicles that exhibit lean driveability symptoms and may or may not have any Diagnostic Trouble Codes (DTCs) stored in memory.

ACTION: Follow the diagnostic procedures described in the following Service Tip. The revised diagnostic procedure is a more accurate means of diagnosing the symptoms.

SERVICE TIP MASS AIR FLOW (MAF) DISCUSSION

MAF sensors can get contaminated from a variety of sources: dirt, oil, silicon, spider webs, potting compound from the sensor itself, etc. When a MAF sensor gets contaminated, it skews the transfer function such that the sensor over-estimates air flow at idle (causes the fuel system to go rich) and under-estimates air flow at high air flows (causes fuel system to go lean). This means Long Term Fuel Trims will learn lean (negative) corrections at idle and learn rich (positive) corrections at higher air flows.

If vehicle is driven at Wide Open Throttle (WOT) or high loads, the fuel system normally goes open loop rich to provide maximum power. If the MAF sensor is contaminated, the fuel system will actually be lean because of under-estimated air flow. During open loop fuel operation, the vehicle applies Long Term Fuel Trim corrections that have been learned during closed loop operation. These corrections are often lean corrections learned at lower air flows. This combination of under-estimated air flow and lean fuel trim corrections can result in spark knock/detonation and lack of power concerns at WOT and high loads.

One of the indicators for diagnosing this condition is barometric pressure. Barometric pressure (BARO) is inferred by the Powertrain Control Module (PCM) software at part throttle and WOT (there is no actual BARO sensor on MAF-equipped vehicles, except for the 3.8L Supercharged engine). At high air flows, a contaminated MAF sensor will under-estimate air flow coming into the engine, hence the PCM infers that the vehicle is operating at a higher altitude. The BARO reading is stored in Keep Alive Memory (KAM) after it is updated. Other indicators are Long Term Fuel Trim and MAF voltage at idle.

NOTE: THE FOLLOWING PROCEDURE MAY ALSO BE USED TO DIAGNOSE VEHICLES THAT DO NOT HAVE FUEL SYSTEM/HO2S SENSOR DTCs.

Symptoms

Lack of Power

Spark Knock/Detonation

Buck/****

Hesitation/Surge on Acceleration

Malfunction Indicator Lamp (MIL) Illuminated - DTCs P0171, P0172, P0174, P0175 may be stored in memory

OBDII DTCs

P0171, P0174 (Fuel system lean, Bank 1 or 2)

P0172, P0175 (Fuel system rich, Bank 1 or 2)

P1130, P1131, P1132, (HO2S11 lack of switching, Bank 1)

P1150, P1151, P1152, (HO2S21 lack of switching, Bank 2)

OBDI DTCs

181, 189 (Fuel system lean, Bank 1 or 2)

179, 188 (Fuel system rich, Bank 1 or 2)

171, 172, 173 (HO2S11 lack of switching, Bank 1)

175, 176, 177 (HO2S21 lack of switching, Bank 2)

184, 185 (MAF higher/lower than expected)

186, 187 (Injector pulse width higher/lower than expected)

NOTE: DO NOT DISCONNECT THE BATTERY. IT WILL ERASE KEEP ALIVE MEMORY AND RESET LONG TERM FUEL TRIM AND BARO TO THEIR STARTING/BASE VALUES. THE BARO PARAMETER IDENTIFICATION DISPLAY (PID) IS USED FOR THIS DIAGNOSTIC PROCEDURE. ALL OBDII APPLICATIONS HAVE THIS PID AVAILABLE. THERE ARE SOME OBDI VEHICLES THAT DO NOT HAVE THE BARO PID, FOR THESE VEHICLES OMIT THE BARO CHECK AND REFER ONLY TO STEPS 2, 3, AND 4 IN THE DIAGNOSTIC PROCEDURE.

1. Look at the BARO PID. Refer to the Barometric Pressure Reference Chart in this article. At sea level, BARO should read about 159 Hz (29.91 in. Hg). As a reference, Denver, Colorado at 1524 meters (5000 ft.) altitude should be about 144 Hz (24.88 in. Hg.). Normal learned BARO variability is up to ±6 Hz (±2 in. Hg.). If BARO indicates a higher altitude than you are at (7 or more Hz lower than expected), you may have MAF contamination. If available, Service Bay Diagnostic System (SBDS) has a Manifold Absolute Pressure (MAP) sensor that can be used as a barometric pressure reference. Use "MAP/BARO" test under "Powertrain," "Testers and Meters." Ignore the hookup screen. Connect GP2 to the reference MAP on the following screen.

NOTE: REMEMBER THAT MOST WEATHER SERVICES REPORT A LOCAL BAROMETRIC PRESSURE THAT HAS BEEN CORRECTED TO SEA LEVEL. THE BARO PID, ON THE OTHER HAND, REPORTS THE ACTUAL BAROMETRIC PRESSURE FOR THE ALTITUDE THE VEHICLE IS BEING OPERATED IN. LOCAL WEATHER CONDITIONS (HIGH AND LOW PRESSURE AREAS) WILL CHANGE THE LOCAL BAROMETRIC PRESSURE BY SEVERAL INCHES OF MERCURY (±3 Hz, ±1 in. Hg.).

NOTE: BARO IS UPDATED ONLY WHEN THE VEHICLE IS AT HIGH THROTTLE OPENINGS. THEREFORE, A VEHICLE WHICH IS DRIVEN DOWN FROM A HIGHER ALTITUDE MAY NOT HAVE HAD AN OPPORTUNITY TO UPDATE THE BARO VALUE IN KAM. IF YOU ARE NOT CONFIDENT THAT BARO HAS BEEN UPDATED, PERFORM THREE OR FOUR HEAVY, SUSTAINED ACCELERATIONS AT GREATER THAN HALF-THROTTLE TO ALLOW BARO TO UPDATE.

2. On a fully warmed up engine, look at Long Term Fuel Trim at idle, in Neutral, A/C off, (LONGFT1 and/or LONGFT2 PIDs). If it is more negative than -12%, the fuel system has learned lean corrections which may be due to the MAF sensor over-estimating air flow at idle. Note that both Banks 1 and 2 will exhibit negative corrections for 2-bank system. If only one bank of a 2-bank system has negative corrections, the MAF sensor is probably not contaminated.

3. On a fully warmed up engine, look at MAF voltage at idle, in Neutral, A/C off (MAF V PID). If it's 30% greater than the nominal MAF V voltage listed in the Powertrain Control/Emissions Diagnosis (PC/ED) Diagnostic Value Reference Charts for your vehicle, or greater than 1.1 volts as a rough guide, the MAF sensor is over-estimating air flow at idle.

4. If at least two of the previous three steps are true, proceed to disconnect the MAF sensor connector. This puts the vehicle into Failure Mode and Effects Management (FMEM). In FMEM mode, air flow is inferred by using rpm and throttle position instead of reading the MAF sensor. (In addition, the BARO value is reset to a base/unlearned value.) If the lean driveability symptoms go away, the MAF sensor is probably contaminated and should be replaced. If the lean driveability symptoms do not go away, go to the PC/ED Service Manual for the appropriate diagnostics.

NOTE:

DUE TO INCREASINGLY STRINGENT EMISSION/OBDII REQUIREMENTS, IT IS POSSIBLE FOR SOME VEHICLES WITH MAF SENSOR CONTAMINATION TO SET FUEL SYSTEM DTCs AND ILLUMINATE THE MIL WITH NO DRIVEABILITY CONCERNS. DISCONNECTING THE MAF ON THESE VEHICLES WILL, THEREFORE, PRODUCE NO IMPROVEMENTS IN DRIVEABILITY. IN THESE CASES, IF THE BARO, LONGFT1, LONGFT2, AND MAF V PIDs INDICATE THAT THE MAF IS CONTAMINATED, PROCEED TO REPLACE THE MAF SENSOR.

After replacing the MAF sensor, disconnect the vehicle battery (5 minutes, minimum) to reset KAM, or on newer vehicles, use the "KAM Reset" feature on the New Generation Star (NGS) Tester and verify that the lean driveability symptoms are gone.

OTHER APPLICABLE ARTICLES: NONE

WARRANTY STATUS: INFORMATION ONLY

OASIS CODES: 206000, 610000, 610500, 610600, 610700, 611000, 611500, 612000, 612500, 614000, 614500, 614600, 698298

-------------------------

Source: by Ford via miesk5

Thank you miesk5. I can't get it in my shop right now because I have so much other junk I'm working on in there now but when I clear out some of it or it gets warmer outside I'll do some checking. I'm thinking I have a faulty fuel pump. From the looks of the fuel filter I replaced the tank probably could use a good cleaning also and also the fact that the gauge isn't working leads me to suspect I have problems there. I'll be back once I can do a little checking a few things out.

I finally got a hole large enough to get the truck inside my shop and what I found was......well what I thank is going on is I have bad connections at the plug going into the fuel tank. I drove it home after being stuck on the side of the road for an hour and it drove like it was brand new. All I did to get it to going was shake the wire harness at the tank and it fired right up. 

I got it home and it sat for a couple days and when I went to start it, it wouldn't start again. After several tries I decided to go to the back of the truck and shake those wires again and again it started right up. I let it run and went inside the shop to finish cleaning out a spot; I was gone about 5 minutes and when I went to pull it into the shop it had cut off. It started back up but cut off several times before I finally got it into the shop.

I decided to go ahead and pull the tank because the gauge was not working either. After getting those stupid bolts off the tank holding bracket.......busted three 15mm sockets,  a whole hand full of busted knuckles and a whole lot of cussing I finally got the tank down enough that I could unhook everything and drop the tank.

Just as I suspected, when I unsnapped the wire harness I could see the connectors were badly corroded. I pulled the pump assy out of the tank and looked everything over. The tank was fairly clean but I plan on giving it a good cleaning anyway. I looked at the float and at first it looked ok but as the unit lay on the ground while I was inspecting the other pieces I noticed a ring of gas expanding out from the float and when I picked it up I could see it leaking. So that explains why the fuel gauge wasn't working also.

My question is where would you get a float. I see where several people have said they are not but a couple dollars but I have tried several places such as.Rock auto, advance auto, pep boys and they don't seem to carry them. I hate to have to buy a new sending unit if just to get a float. 

I was thinking about buying a new pump and res but I see where several people also noted to not buy a cheap pump because they don't last. What is a cheap pump? I was looking on Rock auto and they have a Denso and a bosch pump for around $110.00 range and I've always had pretty good luck with those parts. Are they considered cheap parts or should I just go to ford and buy a $400.00+ pump and be done with it? The ford part though is the complete unit sender and all.

I was just wondering about this before I spent a lot of money and had to do this again next week.

Check out LMC Truck, this page might have what you are looking for http://www.lmctruck.com/icatalog/fd/search.aspx?searchTerms=float&rURL=/icatalog/fd/t.aspx

Good Luck,

>-

yo,

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Composite Sending Unit Float, 66-96

Item Number: 10223

Unit Price: $12.00



http://shop.broncograveyard.com/Composite-Sending-Unit-Float-66-96/productinfo/10223/

I know that some 92-96 Bronco owns have used Walbro pumps and others, but have never come back to update the status of these non-Ford pumps.

I know that AMAZON has some lower prices...they are VG at delvy and esp pricing; I bought a $150.00 DPFE Sensor for $50.00 with free shipping and no sales tax; Local dealers wanted 150.0 +

same price & discount for an Idle Air Control (IAC)

Motorcraft PFB4 Fuel Pump and Hanger Assembly

http://www.amazon.com/Motorcraft-PFB4-Fuel-Hanger-Assembly/dp/B000C5DR2G/ref=sr_1_17?ie=UTF8&qid=1425051353&sr=8-17&keywords=96+bronco+fuel+pump

READ THE 6 customer reviews !!!

Examples;

"Fits perfectly in a 1995 Bronco Eddie Bauer 5.8L. You will need the WT56822 adapter as specified in the Ford parts literature as this pump is an obsolete part and does not mate with the original harness connector. Also does not come with the PS22 Fuel tank sender, but if memory serves neither did the old stock pump. A pump hanger is also needed, but when you are a... "

"This part DOES NOT include the fuel level sensor and float as shown in the the picture. Also, you will want the WT56822 connector as the connector on this fuel pump DOES NOT mate with the original connector. Aside from that, it worked as intended. "

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•Efficient single-stage turbine design

•Exceptional hot fuel handling capability

•Reliable in-tank operation

•Precision-balanced armature for low noise and vibration

•Maximizes performance

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Section 10-01A: Fuel Tank, Filters, Tubes and Electric Fuel Pump, Gasoline Engines

http://www.diesel-dave.com/vehic/manual/stj/stja1a21.htm

1996 F-150, F-250, F-350, F-Super Duty and Bronco with Gasoline Engines Workshop Manual (PARTIAL)

REMOVAL AND INSTALLATION

Fuel Tank Sending Unit and Pump, F-150, F-250, F-350, Bronco, and F-Super Duty

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90-96 Fuel Pump System Install by Steve @ http://www.supermotors.net/clubs/superford/registry/2742/12737