ECM, Ground, or other problems?

[Sandman8105]

On my 89 5.0, I keep getting codes 21, 22, 34, 42, and 77. I replaced the o2 and map sensors while I am waiting on the egr, temp sensor, iac valve, and egv to arrive. Reset everything and I still get all of the codes. I have checked and replaced all vacuum lines also. As well, the tach isn't reading but, I figure that is something different. It idles rough.i give it a little throttle and things smooth out. Just wondering if it is still throwing these codes after resetting it, does it sound like the ecm is bad, a bad ground somewhere, or something else? Thanks for any help.

 

[miesk5]

Yo,

You can pull and open the ecm and look for leaky capacitors, see:

http://broncozone.com/topic/20788-fuel-delivery-problem/

Inforum and pics by seedpress

Ecm Removal

Remove the drivers inside kick panel adjacent to the pedals. It comes out through the cabin.

Should be one small metal ***** holding it. Just slide it out, but be careful with the gasket for the firewall. Don't mess it up and you can reuse it.

should have a sticker in the driver's doorjam with whatever program the computer is. Or

On the ecm, see http://web.archive.org/web/20110720083609/http://www.fordfuelinjection.com/?p=17

Will post DTC info next.

 

[miesk5]

Yo

DTC 21 ECT out of self test range 0.3 to 3.7 volts; "... ECT is bad, ***engine not warmed up***, bad thermostat, low coolant..***Coolant is less than 50 deg F for KOEO, or less than 180 deg F for KOER, or greater than 250 deg F for either.*** If coolant temp is in proper range, suspect ECT sensor or it's connector/wiring..."

Testing; "..."But due to its simplicity of design, the ECT is rarely at fault when problems occur. Before testing the ECT or any other EFI component perform a self-test, trouble codes received during test can be used as a diagnostic tool along with other indicators. To test an ECT sensor you will need a volt meter. You can test the ECT by back probing the harness while reading the voltage returning to the EEC. Or you can removing the connector completely and test the resistance between the 2 pins on the ECT..." READ MORE Source: by Ryan M (Fireguy50)

http://web.archive.org/web/20140218014322/http://oldfuelinjection.com/?p=28

DTC 22 indicates the Manifold Absolute Pressure (MAP) sensor is out of Self-Test range. Correct MAP range of measurement is typically from 1.4 to 1.6 volts. Possible causes:

MAP circuit open between sensor vehicle harness connector and PCM.

MAP circuit shorted to VREF, SIG RTN, or GND.

Damaged MAP sensor.

Vacuum trapped at MAP sensor.

High atmospheric pressure.

Damaged PCM.

VREF circuit open at MAP/BARO sensor.

SIG RTN circuit open at MAP/BARO sensor.

DTC 34- EGR voltage above closed limit - Failed sensor, carbon between EGR pintle valve and seat holding the valve off its seat. Remove the EGR valve and clean it with carbon remover. Prior to re-installing see if you can blow air through the ****** side of the EGR by mouth. the egr is not closing properly which can cause detonation. remove the egr and clean off any carbon built up on it with carb cleaner and a brush if necessary.

Testing... "...EVR Testing: vacuum should vent from the green line on a good valve NOT energized. When energized, vacuum should hold from the black to the green. Resistance across the terminals should be 20-70 ohms..."

DTC 31, 32. 33. 34. 35. 38 or 84 - EGR Valve Position (EVP) Sensor & EGR Vacuum Regulator Solenoid (EVR) Testing

Source: by Dustin S (Dustball, Mellow Yellow, Mr. Laser Boy) at http://ylobronc.users.superford.org/documents/egr/

DTC 42 O2 sensor voltage was stuck high for too long. (Rich).; "...Bad O2, or it's connector/wiring bad MAP sensor, Bad fuel pressure regulator, pull vac hose off, any gas in it or gas aroma means it's bad; Leaking injectors,restriction in fuel return line,or exhaust leak or clogged exhaust, lowering vacuum..." 42, Check for proper HEGO Ground; in Catalytic Converter Diagnosis TSB 91-12-11 for 86-91 Bronco, F Series, & Econoline

by Ford

the following areas may be at fault:

* Ignition Coil

* Distributor Cap

* Distributor Rotor

* Fouled Spark Plug

* Spark Plug Wires

* Air Filter

* Stuck Open Injector

* Fuel Contamination Engine OIL

* Manifold Leaks Intake/Exhaust

* Fuel Pressure

* Poor Power Ground;

Source: by miesk5

DTC 77 system failed to recognize brief WOT dynamic resistance test. Need to press gas pedal during KOER; Operator didn't execute WOT when told to during self test.

TPS, MAP and KS sensors are exercised during the brief Wide-Open Throttle (WOT) performed during the Engine Running Self-Test. The signal for the operator to perform the brief WOT is a single pulse or 10 code on the STAR Tester.

If you have a TPS, MAP or KS code in KOEO; troubleshoot those and repair until Code(s) is gone in KOEO; then try KOER and WOT (dynamic response check).

 

[Sandman8105]

I pulled the ecm last night and carefully opened and inspected the board. Looked brand spanking new. No burned spits and no burnt smell. Put it all back together last night and re connected the batt this morning and the rpm's at idle sound better than yesterday; not fluctuating. Still sounds a little rough like maybe plugs and wires (which I just picked some up). Grounds looked pretty good. The two from the frame to the core support looked dirty and rusty (last night) so I wiggled them and I will wire brush them off in a bit. I will also re-run the koer test and see if anything changed since this. I am also going to replace the fuel regulator for ***** and giggles and then I will just be waiting for the egr, egv, iac, and the temp sender to arrive and be installed (probably tomorrow). I'll keep you posted till this thing is running right. I greatly appreciate your help.

 

[Sandman8105]

What is this code 12 "throttle kicker" about?

 

[miesk5]

Yo,

DTC 12 can't control engine RPM high RPM self test; vacuum leak, TB base idle off, IAC dirty or bad, EGR stuck open. Check the IAC valve port in TB for Sludge; Suspect throttle body coking.

Idle Air Control (IAC); also called, Idle Air Bypass (IAB), Idle Speed Control (ISC), Throttle Bypass Air, Idle Bypass, Inlet Air Controller, Inlet Air Bypass, Intake Air Bypass, Intake Air Control

Idle Air Control (IAC) Sludge; Poor Idle TSB 91-25-07 for 85-92 Bronco & F Series & many others; "...Hard cold starts, hesitation and stalls on initial start-up or during idle or decel may be caused by sludge in the throttle body and/or idle by-pass valve. Sludge deposits or oil film on the throttle body bore and plate or the idle air by-pass valve may cause one or more of the following conditions. Hard Cold Start, Stall On Initial Start-Up, Stall During Idle, Stall During Decel, Rough Idle, Rolling Idle, Hesitation During Acceleration. A new idle air by-pass service kit (F2PZ-9F939-A) is now available for service use to correct sludge contamination concerns of the throttle bore and plate only. It eliminates the need to clean the majority of past model throttle body applications. Cleaning is not required on sludge tolerant throttle body designs released for 1991 and newer model years..." Source: by Ford

Nelbur wrote here,

"I have spent some time this week trying to set up an air bypass around the IAC valve by cutting away some of the gasket between the IAC in and out air holes, rather than pay big bucks for Fords spacer kit. I cut away the center of the original IAC gasket from the outside of each hole to the outside of the other hole, giving about 1/2" gap for the air to pass through. I noticed an immediate improvement in the engines starting behavior, but it would still die occasionally.

For most of my trucks life it has been dying when it was started hot. It would rev up and then drop the idle so low it would die unless I would catch the idle with the accelerator. It would never die when cold as the IAC would keep the idle speed up, and it never died at stop lights. Now it's worst situation seems to be when it has been shut down for a half hour or so, and restarted. I wonder if the heat soak is fooling the ETC into thinking the engine is warmer than it really is.

I decided that more improvement could be had if I had a thicker gasket, because the original IAC gasket was very thin (0.018"). I had some 0.030" gasket material so I made my own with the same 1/2" cut out. This gave enough bypass to noticeably raise the idle speed and almost eliminate the dying. After maybe 50 starts in the last few days, it only died twice. After so many years of catching it with the accelerator it is darned hard to leave my foot off it. It is clear to me that by trial and error one can tune the air bypass without the need for the expensive Ford kit. I may combine the two gaskets for more bypass, but the idle is about as fast as I would want now, especially for driving in snow."

http://broncozone.com/topic/22150-fast-idle-problem/?pid=115710

Post #12

 

[Sandman8105]

Bad egr. Pulled the vacuum line off and she purrs like a kitten, put it back on and she spits and spudders. New egr and iac valve will be here today. Thanks for your help. I greatly appreciate it.

 

[Sandman8105]

Now, to figure out if I have a bad wire on the tach or if the tach is dead. I'll start a new thread for that.

 

[miesk5]

Yo,

Inspect coil connector for loose wires, corrosion & squirrel bite marks.

Inspect Ground G801 On LH inner fender behind headlights

Tach Wiring Diagrams:

supermotors.net/getfile/648663/thumbnail/86-bronco-wiring-diagram-section-2.jpg[/img][/url]

in an 86 by Xris

similar to this 89 diagram;

http://www.revbase.com/BBBMotor/Wd/DownloadPdf?id=21140

3rd diagram from top

In case you need to swap the gauge:

Cluster, w/Tach Pic, Back View w/Connector, Terminal & Bulb Identification in 87-91



For fuel level problems, try polishing the film circuit contacts (A & B 1-14) with brown paper or a pink eraser, especially those related to the fuel gauge. Be careful NOT to peel the copper strips off the mylar film.

A1 - Seat Belt - DG/LG

A2 - Hi Beam - LG/Bk

A3 - Ground - Bk

A4 - Illumination - LB/R

A5 - unused

A6 - Tachometer - DG/Y

A7 - V8 ground - Bk/Y

A8 - R Turn - Wh/LB

A9 - ABS - DG

A10 - 4WD - LB

A11 - Low Range - LB/Bk

A12 - Fuel - Y/Wh

A13 - Gauges & Warning Lights Power - R/Y

A14 - unused

B1 - Oil - Wh/R

B2 - Ground - Bk

B3 - L Turn - LG/Wh

B4 - unused

B5 - Gauges & Warning Lights Power - R/Y

B6 - unused

B7 - Emissions - Bk/LB?

B8 - Brake - Pu/Wh

B9 - CEL - Pk/LG

B10 - Ground - Bk

B11 - Temperature - R/WH

B12 - IMS/EUL - Wh/R?

B13 - Charge - LG/R

B14 - Ig.Sw. - R/LG

by Steve

Similarities, Mounting, & Removal info & pics; "...The PSOM, lens, blackout ring, terminal clips, shifter plates, bulbs & holders are interchangeable between cases. 87-96 gauges are only held in by their terminal clips, except the speedo. 80-91 speedos are held in by 2 screws; 92-97 PSOMs are held captive by the surrounding gauge faces. 80-86 use the same case for tach & non-tach, with a blank face for non-tach. 80-86 gauges are held in by stamped nuts on threaded studs. The fuel, oil, & temperature gauge bodies are identical & interchangeable by prying the needle off & removing the 2 screws holding the body to the face plate. To reinstall the needle, the gauge must be powered & have a known signal applied (usually the minimum) before stabbing the needle so it points to the proper reading. The screws are 5.5mm (7/32") hex with T15. Note that both cases have a molded socket for an anti-slosh module (low fuel light, which was never installed at the factory) and both film circuits have 4 traces for the socket..."

by Steve