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66-96 Ford Broncos - Early & Full Size
James Kiehl

'90 5.8L getting continuous code 33 and running code 44

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Hey all,

 

New member. Thanks for having me. I have a 90 5.8 L that has failed Colorado emissions on carbon monoxide levels.

 

Already Replaced:

Plugs

Plug wires

Air filter

Pcv filter

PVC valve

MAP sensor

Oxygen sensor

EGR valve position sensor

IAC unit

 

As of now, codes generated:

KOEO - 11 - passed

Continuous - 33 EGR valve not opening

Running - 44 secondary air inoperative

 

My brain is locking up, so I could use a bit of help if you can.

 

Thanks,

Jim

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yo JAMES,

 

WELCOME!

 

 

CM KOER

- 33 EGR valve not opening

DTC 33 is triggered when the EVP sensor is not closing;

 

Testing & Operation; "...The EGR Valve Position (EVP) sensor monitors the position of the EGR valve pintle. The EVP sensor converts the mechanical movement of the pintle into an electrical voltage signal which is relayed to the PCM. The EVP sensor is a linear potentiometer in which resistance varies with the EGR valve pintle movement.

Voltage is fed to the EVP by the signal return circuit. As the EGR is opened the EVP directs more voltage to the EEC and less down the voltage reference circuit. The EVP sensor provides the PCM with information on EGR flow and EGR system failures. The EVP should read between 0.24 and 0.67 volts at idle with a closed EGR valve..." read more

Source: by Ryan M (Fireguy50) at http://web.archive.org/web/20130912124008/http://www.oldfuelinjection.com/?p=35

excerpts;

Damaged EVP sensor

•Corroded or dirty connector

•Damaged EGR valve

•Faulty Vacuum system

•Broken wire in harness

•Grounded harness

•Damaged Computer

I know you did the vac leak test, but pull vac hose off @ EVP - I pull em off and use the straw sucking test; one finger over one end; and... ya get the idea?

 

 

Testing & Operation; "...The EGR Valve Position (EVP) sensor monitors the position of the EGR valve pintle. The EVP sensor converts the mechanical movement of the pintle into an electrical voltage signal which is relayed to the PCM. The EVP sensor is a linear potentiometer in which resistance varies with the EGR valve pintle movement.Voltage is fed to the EVP by the signal return circuit. As the EGR is opened the EVP directs more voltage to the EEC and less down the voltage reference circuit. The EVP sensor provides the PCM with information on EGR flow and EGR system failures. The EVP should read between 0.24 and 0.67 volts at idle with a closed EGR valve..." read more Source: by Ryan M (Fireguy50) at http://oldfuelinjection.com/?p=35

 

EVP is light gray & attached to the top of the EGR Valve

EVP PIC by Waltman change-oil-pan-gasket-and-valve-cover-ga

 

 

 

 

CM KOER

DTC 44 Thermactor Air Injection system inoperative (Right side).

DTC 44 (KOER); Right Thermactor Inoperative; "...I had a similar issue that turned out to be the vacuum line to the Thermactor Air Bypass Valve. No CEL, just a code; 1. First check that the two vacuum lines are connected to the Vacuum Reservoir (coffee can) and the resevoir is in good repair with no leaks on the bottom. Frequently the can leaks or the vacuum lines are accidentally knocked off. Check the vacuum hose to the bottom of the Bypass Valve. Check the vacuum hose to the Diverter Valve. Check the vacuum hoses to the TAB/TAD Solenoids. Then check your TAB/TAD Solenoids. These are common easy to miss problems. Once these are ruled out all that is left is: Thermactor Air Supply Hoses. One-way Check Valves. Main TAB/TAD Valves..."

Source: by Seattle FSB (SeattleFSB) at http://fullsizebronco.com/forum/showthread.php?t=168505

 

 

DTC 44 (KOER) - Right Thermactor Inoperative - The thermactor system injects air into the exhaust ports in the heads downstream from the valves. Air is supplied from the smog pump through tubing and the TAD/TAB valves to a copper pipe between the heads on the firewall side of the engine, and ultimately to the exhaust passages. If your smog pump is disabled, or your disconnected the tubing or blocked the thermactor holes in the back of the heads, or if the TAD/TAB valves are bad, you will get these codes. My car has all of this stuff removed and used TFS Track Heat heads (with no thermactor provision), and naturally pulls these codes.

Source: by Matthew

 

 

DTC 44 (KOER); Right Thermactor Inoperative; "...indicates a Thermactor Air System leak which could be anywhere from the smog pump up front to include EGR solenoiids over on the right inside fender liner and all the way to the back of the engine which is what you see in the photos. There is also a smog tube that runs along the passenger side engine below the valve cover which runs to the back of the FI plenum up to a Air Bypass Valve (plastic) crossing over to the cross-over tube (exhaust) which is connected to that and the CAT, check valve and tube below. the Thermactor system is designed to capture spent gases and ultimatley send them down to the CAT to burn off etc.If you look closely you'll see the chek valve and CO tube is pipe threaded, use some anti-seize and don't over tighten and when putting the valve on the tube, you don't need a gasket for the CO tube ends but rather just use some bearing grease which melts and forms a nice gasket seal.....this is a tip from Steve83; gaskets burn off and go away after a while and you're back with another vacuum leak etc..."

Source: by JKossarides ("The Bronco", Jean) at http://fullsizebronco.com/forum/showthread.php?t=150013

 

 

DTC 44 Problems in the Thermactor Air Control system. Check vacuum lines, air pump, diverter valve, and solenoids.

Source: by miesk5

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Whew, thanks a lot. I think I will do a full vacuum check first, seems like both codes could be caused by that issue.

 

Thanks. Will update with progress, if I have any!

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I am working to get the tools to test the vacuum lines, but in the meantime, here is a scan of my latest emissions fail, if anyone cares to have a look.

 

Thanks!

Jim

 

Page 1

 

Page 2

Edited by James Kiehl

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Ok, I'm back. New EGR valve, new vacuum test gauge in hand.

 

I am now pulling:

KOEO -34

Continuous - 11 (pass)

Running - 34

 

I have done a vacuum check on the ported vacuum line.

 

No vacuum at idle - correct.

Increase RPM to 3500 - problem (I think). Vacuum increases until about 3100 RPM, then cuts out. Very repeatable.

 

Why would the vacuum drop out early?

 

Going to check the temp switch next, and the vacuum line. Any other suggestions?

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yep, i can pull a vacuum with the test rig, but the solenoid is not allowing it under operation. it is really perplexing. Here are the two specific issues i have right now:

 

The EGR position sensor (or EVP) harness should show a Vref of 4-5 volts. I am showing between 1 and 2 volts. I tested the TPS harness for the Vref voltage and also got between 1 and two volts. i checked continuity to the EEC harness (60 pin connector) for those leads and everything seemed to check out, so i guess the Vref is truly low.

 

My EGR solenoid was not holding vacuum on the input side, so i purchased a new one - same problem, purchased a second new one - same problem (right out of the box). Either i am not understanding the test procedure (disconnect the electrical lead and vacuum hoses and apply vacuum to the inlet port) or i happened to get two defective solenoids in a row. whatever the case, i can no longer even get the vacuum up to 3100 RPM that i was seeing in my previous post, there is no vacuum generated at all)

 

Other points: the input (manifold) vacuum to the EGR solenoid registers above 10 inHg, so the supply is working, but the solenoid itself does not seem to be allowing the vacuum to be transferred to the input port on the EGR valve itself.

 

Thanks for any insight, i'm going to battle the Vref at this point.

Edited by James Kiehl

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Sorry... I have a mental block when it comes to the EGR.

 

Regarding the low Vref, You might want to check a couple of grounds.

Particularly from the battery to the frame and engine, look for a ground strap to the body, check the two small ones to the upper radiator support (one on the left, and one on the right) and the one to the EEC/PCM near the driver's side hood hinge.

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Ok, looks like the battery to frame ground is beat up and corroded, time to replace that. The two that you mention that go to the radiator might be mounted to the same stud that the battery ground is mounted, on my truck. Checking the one by the hinge, also. Thanks. Will report back.

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Important grounds are

 

1. Battery to frame and engine block 

2. intake manifold to fire wall

3. Head light ground to the inner fender (one on each side near the head light)

4. Hood ground (mainly for preventing ignitionnoise in thr radio)

5. Undre dash ground (usually to the right of the gas pedal)

 

etc.

 

Start with those.

 

:)>-

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Ok, sounds good, for some reason I had the solenoid operation and test mixed up in my head. Thanks.

 

I'm still struggling with the Vref signal at less than 2V. It should be 5V, and now I'm suspecting that the ERC-IV module itself might have a faulty component (capacitor failure, perhaps) that is preventing the system from having 5V. The EGR position sensor voltage is provided by the TPS harness, so if the TPS can't show the proper position, the solenoid doesn't open, the EGR pintile never moves, the voltage never changes from zero, and the feedback loop doesn't work.

 

Anyone have some insight on removing and examine, repairing, or replacing the EEC-IV module?

 

Thanks for the help so far!

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Update: checked all grounds except one. Could not find a ground next to the gas pedal.

 

They were decent, but I cleaned them all and replaced the battery (-) to chassis wire.

 

I still think the ref is not bring properly provided by the PCM module.

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yo.

by Joel

To check that the VREF (reference voltage) generated by the PCM power supply is good, meter between pin 26 of the PCM and a good frame ground.

You can do the "wiggle" test on the harness to make sure there are no weak or loose connections between the sensor connector and the PCM.

EEC IV Connector Pin Depiction Pic and LEGEND by Ryan M (Fireguy50)  miesk5

http://broncozone.com/topic/23573-pulled-codes/

 

EGR VALVE POSITION SENSOR Testing & Operation
Source: by Tomco Inc. tomco-inc.com

 

 

1988-1991 TPS Wire Colors
VREF - Orange/White
 

Oartial VRED Voltage could be a bad capacitor.

Capacitor Repair in a 90 5.8
Source: by seedpress (dolittle) at Ford Bronco Zone Forums

 

 

Ground; Location Diagram, Engine Area in a 90; G102, G105, G107, G108

Source: by Seattle FSB (SeattleFSB) at SuperMotors.net

 

Location in Engine Bay Diagram in a 90 5.0 & 5.8 Page 2; G100, G104
Source: by Seattle FSB (SeattleFSB) at SuperMotors.net Location in Engine Bay pics: G100 @ LH front of engine compartment on upper radiator support-in front of WS washer/Coolant overflow tank; G101 front of fender apron-between starter relay & headlight; G200 behind RH kick panel; G103 (battery to engine) Lower RH front of engine; Same as Bronco in a 95 F Series
Source: by Ford via subford (Bill K) at photobucket Location in Frame Rail Diagram in a 90; G 101, G401
Source: by Seattle FSB (SeattleFSB) at SuperMotors.net Location in Full Body Diagram in a 90; G500
Source: by Seattle FSB (SeattleFSB) at SuperMotors.net

G201, G205 Location Diagram, Behind Dash in a 90
Source: by Seattle FSB (SeattleFSB) at SuperMotors.net

 

 

 

Locations in a 90 from 1990 Bronco EVTM; G100 LH side of Radiator support G101 RH side of Radiator support G102 RH side of Radiator support G103 LH rear side of engine, near knock sensor G104 LH rear side of engine compartment, near electronic engine control (EEC) module, on the left fender close to the firewall G105 LH Side of engine G106 RH fender apron, near voltage regulator G107 RH fender apron, at starter relay G108 RH fender apron, at voltage regulator G109 RH fender apron G201 LH rear side of I/P (looking at the diagram it is at the bottom of the driver's side dash assembly. Screwed to the bottom edge, just to the left of the steering column. It is the ground for the instrument cluster) G202 Behind RH cowl panel G203 RH rear side of radiator support G204 On steering column G205 Behind Center of I/P (Dash), near speed control amplifier G400 LH side of cargo area, near rear light assembly G401 Below LH side of cargo area, near crossmember G500 Inside driver's door, near left door speaker
Source: by ironmanisanemic

 

Locations in a 90 from 90 Bronco EVTM; "...G100 LH side of Radiator support; G101 RH side of Radiator support; G102 RH side of Radiator support; G103 LH rear side of engine near knock sensor; G104 LH rear side of engine compartment, near electronic engine control (EEC) module, on the left fender close to the firewall; G105 LH Side of engine; G106 RH fender apron, near voltage regulator; G107 RH fender apron, at starter relay; G108 RH fender apron, at voltage regulator; G109 RH fender apron; G201 LH rear side of I/P (looking at the diagram it is at the bottom of the driver's side dash assembly. Screwed to the bottom edge, just to the left of the steering column. It is the ground for the instrument cluster); G202 Behind RH cowl panel; G203 RH rear side of radiator support; G204 On steering column; G205 Behind Center of I/P (Dash); near speed control amplifier; G400 LH side of cargo area; near rear light assembly; G401 Below LH side of cargo area; near crossmember; G500 Inside driver's door; near left door speaker"
Source: by BroncoJoe19 (Joe) at Ford Bronco Zone Forums

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Guys, here are a couple of photos of the board. I only see some discoloration in the upper right of pic #2, closer shot on pic #3. Nothing obvious. Any help on checking the Vref +5 signal? Pin 26, but I can't trace it beyond the first 'hop' to the first component from pin 26.(it's visible on the bottom, same as pic#1)

post-20017-0-34964200-1378764744_thumb.jpg

post-20017-0-05488500-1378764764_thumb.jpg

post-20017-0-15840600-1378764778_thumb.jpg

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OK, new EEC module in place. Vref at 5V. Still pulling these codes:

 

KOEO/Stored/Continuous

34/34/34 and 65

 

I cant figure out why that 34 code (overvoltage) could be happening. ALl the circuits seem to check out. Baffled.

 

Thanks for any insight. I have the links above for Code 34, but i don't know if i've come across any for the continuous 65, so any help is appreciated.

Edited by James Kiehl

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yo,

 DTC 34 in Key On Engine Off (KOEO) or Engine Running (KOER) Self-Test indicates that the EGR valve and/or EGR Valve Position (EVP) sensor may not be fully seated in the closed position. The EVP sensor voltage is greater than the closed limit voltage of 0.67 volt. Because of the preload on the installed EVP sensor, it is very difficult to determine whether the EGR valve is seated or the EVP sensor is in contact with the EGR valve stem.

Possible causes:
Poor continuity in EVP sensor harness.
Non-seated EGR valve.
Damaged EGR valve.
Damaged EVP sensor.
Damaged EVR solenoid.
Damaged Powertrain Control Module (PCM).

EVP sensor is/was high – EVR

EGR Vacuum Regulator (EVR) Solenoid - 9J459
TESTING by TOMCO http://www.tomco-inc.com/Tech_Tips/ttt32.pdf

 

 

Testing & Diagram; "...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..."

 

evrtest.jpg

EVR Location pic in a 90 5.8

http://www.supermotors.net/getfile/848247/fullsize/tab-tad-evr-coil2a.jpg
Source: by SeattleFSB (Seattle FSB)

 

The EGR Vacuum Regulator (EVR) solenoid is an electromagnetic device which controls vacuum output to the EGR valve. An electric current in the coil induces a magnetic field in the armature which pulls on a disk closing the vent to atmosphere. The Powertrain Control Module (PCM) outputs a duty cycle to the EVR which regulates the vacuum level to the EGR valve. As the duty cycle is increased, so is the vacuum signal to the EGR valve. The vacuum source is manifold vacuum.

evrtest.jpg 

 

Testing; "...Remove the EVR solenoid; Attempt to lightly blow air into the EVR solenoid. If air blows through the solenoid, replace the solenoid with a new one. If air does not pass freely through the solenoid, continue with the test. Apply battery voltage (approximately 1 volts) and a ground to the EVR solenoid electrical terminals. Attempt to lightly blow air, once again, through the solenoid. If air does not pass through the solenoid, replace the solenoid with a new one. If air does not flow through the solenoid, the solenoid is OK..." (under license from Delmar Publishers, comb of Chilton/Nichols/Delmar & Haynes); some may be incorrect, as reported by Seabronc, thanks Seabronc! NEW SITE URL!!! MUST REGISTER TO VIEW; select year, make, model, engine size and go to appropriate section
Source: by Chilton via Autozone

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) http://ylobronc.users.superford.org/documents/egr/

 

 

I believe you can skip this portion and test the EGR Vacuum Regulator (EVR); also called EGR Vacuum Solenoid

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OK, thanks for all the help. I have done the diagnostics suggested and came up with this situation:

 

Vref  = 5V, looks good (bought new EEC unit)

EVP resistance range - ~4700 ohms (fully extended) to ~400 ohms (fully compressed) (This is a brand new unit)

EGR valve - brand new, presumably seating properly

EGR solenoid - brand new, functionality checks out

Circuit checks out OK to EVP

Circuit checks out to EGR solenoid (voltage at 10.5V+, as it should be)

 

When i perform the EGR solenoid vacuum test, the manual says to rev the engine to about 3500 RPM and watch the vacuum increase. When i do this, i can get the vacuum to increase as the RPMs increase, but only to about 2700RPM or so, then it drops off back to zero when i go higher. I'm pretty sure this would theoretically be consistent with the reason that i am failing emissions in the first place, high CO at high RPM, if i understand the operation properly.

 

It seems to me as if the system is almost working, but i can't figure out what sort of failure mode would cause the EGR to drop off in operation like it is doing. That behavior, combined with the error code 34 as a voltage out of range, makes me think that there is some kind of offset happening inadvertently, but i cant figure out where. Any ideas would be most appreciated, and thanks for the help so far.

Edited by James Kiehl

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yo

What manual did you get the EGR solenoid vacuum test from?

I can't correlate Code 34 w/your test results and Ford's pos,sibe causes in POST #18 And esp high CO at high RPM - and I agree with you, as for some "offset" is present and adding to DTC 34;

CO Failure is the result of an excessively rich air fuel mixture. The following is a list of the most common causes:

– Defective Oxygen Sensor

– Inoperative Air Injection System (if equipped)

– Leaking or defective Fuel Injectors

– Restricted air filter (especially if high CO is present only at high RPM)

Vacuum leaks resulting in improper MAP sensor operation

– Defective air mass or air flow sensor

– Malfunctioning fuel evaporation system or purge valve

– Defective Catalytic Converter

– Defective thermostat (cooling system), thermostat stuck open

– Oil contaminated with fuel, excessive miles between oil changes

by Lance Wright

http://www.auto-repair-help.com/auto_diagnostics/diagnose_emission_test_failure.php

 

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

VACUUM:

Normal Engine Vacuum at Idle is 15-22 in-Hg for EFI Broncos;

Borrow or purchase a vacuum gauge and read this Vacuum Gauge Diagnosis @ http://www.diesel-dave.com/vehic/manual/stj/stj30013.htm

Similar to other EFI years.

 

One way to do a quick check is to grab a vacuum gauge. Bring the engine to normal operating temperature. Connect gauge to the intake manifold tee. BEWARE OF FAN, BELT, PULLEYS & HIT ENGINE.

The vacuum gauge should read between 15 and 22 in-Hg depending upon the engine condition and the altitude at which the test is performed. SUBTRACT ONE INCH FROM THE SPECIFIED READING FOR EVERY 1,000 FEET OF ELEVATION ABOVE SEA LEVEL.

The reading should be quite steady. .

 

When engine is rapidly accelerated (dotted needle), needle will drop to a low (not to zero) reading. When throttle is suddenly released, the needle will snap back up to a higher than normal figure.

 

When vacuum leaks are indicated, search out and correct the condition. Excess air leaking into the system will upset the fuel mixture and cause conditions such as rough idle, missing on acceleration, or burned valves. If the leak exists in an accessory unit, such as the power brake, the unit will not function correctly. Or Air Conditioning when in MAX mode may switch to Defrost.

●Carbureted Broncos should have between 17 & 21 in-Hg at idle; read this Vacuum Gauge Diagnosis @ http://www.gregsengine.com/using-a-vacuum-gauge.html

High Idle Tips by Mikey 350: "Take off the air intake hoses so you can access the throttle bores. Start the engine and place a piece of stiff cardboard over the throttle bores. That should NOT change a correctly configured engine, as the idle air is only from the opening of the IAC, and nothing through the throttle bores.

If that make a difference, then the throttle plates are slightly open due to the removal of the Teflon coating, or the linkage/return spring/throttle stop is screwed up.

If the engine still runs too fast with the throttle opening blocked, try taking off the IAC and blocking those openings.

What you have done is (supposedly) removed all the "normal" air intakes, and if the engine still runs, you have a vacuum leak.

You could then try leaving the air intakes (throttle and IAC) blocked and cap off the vacuum lines coming off the vacuum tree. (except the MAP line) If one of those makes a difference, investigate the leak.

Check the vacuum line from the vapor canister (on the left side of the throttle, when facing the throttle assembly) (cap it, on the outside chance that the solenoid has failed open) (if equipped)

Pull the EGR connection to the intake and plug or cover it (if you have wide duct tape, use that to cover the hole).

If it still is running with the throttle blocked and the IAC and the lines from the vacuum tree capped, then you have a manifold or PCV line leaking. Plug the PCV line to the intake, then the vacuum line to the brake booster (if it has it's own fitting on the manifold)

Something is causing that high idle, and 95% of the time it is a vacuum leak."

Quick Vacuum Leak Test; On an idling engine check for vacuum leaks using a mechanic's stethoscope, or a ~3' garden hose section. Beware of fan, belts, pulleys & Hot hoses and engine.

On COLD ENGINE only, use propane torch w/rubber hose attached, UNLIT, when it gets to the the leak the RPMs will rise.

Check vacuum hoses & vacuum operated components:

Intake plenum gasket leak on the passenger side and on firewall side is a hard-to-find leak; as well as throttle body gasket; worn throttle shaft and lower intake gasket(s).

With the engine cold, visually and physically check all vacuum hoses. The most common vacuum leak problem is the PCV tube's elbow, where it connects to the intake manifold.

... start her up and spray around the intake manifold's gaskets to check for leaks. If the carb spray hits a spot that is leaking, the engine RPM's will increase or decrease and this will pinpoint the source of the vacuum leak.

Not only will the RPMs increase or decrease, remember, you can't let the engine get hot and continue to spray the intake manifold to cylinder head areas with carb spray. by Abraham Torres-Arredondo

As well as throttle body's worn throttle shaft and lower intake.

vacuum tree Location pic in a 94 5.8 Source: by joelb23 @

vacuum_lines.jpg

Vacuum Block in an 86 by Chris B @ http://chrisb.users.superford.org/Bronco/Projects/Vacuum_Lines/Vacuum_Lines_03.JPG

PCV damaged or vac line leak; make sure the PCV rubber elbow (at the intake manifold) is not torn or that it does not have dry-rot.

Note; use fuel-rated vacuum hose for PCV Valve.

img_20110315_142528.jpg

PCV Valve pic by Bbronco311

101_0141.jpg

PCV VACUUM HOSE PIC In A 95 by Shadofax (TheJuice, The Juice, Mark Z)

Emission System Vacuum Tank aka VRESER, looks like a coffee can in earlier years, but often rusts on bottom; 96s has the improved plastic tank

Location pics in a 95 5.8

vacc-003.jpg

by fordbronco1995 ("JUICE") - replaced it w/Peanut can

The Reservoir stores vacuum and provides "muscle" vacuum. It prevents rapid fluctuations or sudden drops in a vacuum signal such as those seen during an acceleration period.

Vacuum Tank Diagnosis; When charged initially with 15-20 in-Hg vacuum, vacuum loss shall not exceed 0.5 in-Hg in 60 seconds. If it does, replace the reservoir.

Vacuum Check Valve; A vacuum check valve blocks airflow in one direction and frees airflow in the other direction. The check side of this valve will hold the highest vacuum seen on the vacuum side. If not, replace it.

Vacuum Check Valve Diagnosis -

Apply 16 in-Hg vacuum to "check" side of valve and trap. If vacuum remains above 15 in-Hg for 10 seconds, the valve is acceptable.

The EGR Valve is required in EEC systems where EGR flow is controlled by the Powertrain Control Module (PCM) through an EGR Valve Position (EVP) sensor attached to the valve. The valve is operated by a vacuum signal from the EGR Vacuum Regulator (EVR) that actuates the valve diaphragm.

As supply vacuum overcomes the spring load, the diaphragm is actuated. This lifts the pintle off its seat allowing exhaust gas to recirculate (flow). The amount of flow is proportional to the pintle position. The EVP sensor mounted on the valve sends an electrical signal of its position to the PCM.

The EGR Vacuum Regulator (EVR) solenoid is an electromagnetic device which controls vacuum output to the EGR valve. An electric current in the coil induces a magnetic field in the armature which pulls on a disk closing the vent to atmosphere. The Powertrain Control Module (PCM) outputs a duty cycle to the EGR Vacuum Regulator (EVR) that regulates the vacuum level to the EGR valve. As the duty cycle is increased, so is the vacuum signal to the EGR valve. The vacuum source is manifold vacuum.

egrtubesv8.jpg

EGR Vacuum Regulator (EVR);

http://www.supermotors.net/registry/media/852022

Check vacuum hose; & valves for damage

& 2ndry air;

Thermactor Air Bypass Solenoid (TAB, AIRB, AM1) w/Pink vacuum line & Air Bypass Valve (AIR BPV) & Thermactor Air Diverter Solenoid (TAD, AIRD, AM2) w/Yellow vacuum line & Air Diverter Valve or Air Control Valve (ACV)

Location pic in a 90 5.8; "...Be advised that the ACV (Air Control Valve) is the TAD (Thermactor Air Diverter) Valve and the AIR BPV is the TAB (Thermactor Air Bypass) Valve. The VRESER is the Vacuum Reservoir Can where the red & black vacuum lines plug into; On my 1990 ex-5.8L, the Yellow Vacuum Line goes from the TAD Solenoid (driver's side forward solenoid) to the TAD (Diverter) Valve located at the rear of the Intake Manifold.

You have to climb up onto the engine to feel the Diverter Valve or remove the Intake Manifold. I'd rather climb up using plans, ala a scaffolding type set-up; maybe remove hood depending on circumstances such as me now, w/ backache..."

tad.jpg

thermactor-tad-air-diverter-valve.jpg

thermactor-air-diverter-valve.jpg

thermactor-air-bypass-valve.jpg

TAB

Source: by Seattle FSB (SeattleFSB)

tab-tad-evr-coil2a.jpg

Source: by Seattle FSB (SeattleFSB

See Seattle's Emission section @ http://www.supermotors.net/registry/20487/76033

Later years used a combo TAD/TAB Valve on Crossover tube

http://www.supermotors.net/getfile/1068900/thumbnail/combination-valve.jpg

Depiction by Seattle FSB

HVAC System (AC, heater, defroster), vent control ckt & vacuum tank (plastic ball, or an irregular box glued to the evaporator cover), under dash & lines to heat/blend/etc. doors; & HVAC vacuum reservoir;

Outside Air/Recirculated Air Door Vacuum Motor Mini-Tube Vacuum Hose Damage Repair in a 92, similar to earlier years & 92-96 Source: by JohnMcD348 @ http://www.fullsizebronco.com/forum/23-technical-write-ups/175808-how-i-fixed-my-c-vac-leak.html

Check Valve & Tank Location pic in a 93; "...valve is about a foot down the vacuum line coming off the 'tree' on the engine Plenum. One of the lines on the check valve tee goes to the built-in reservoir on the a/c box, the other into the loom with the white tube heading for the control panel inside ..."

http://fullsizebronco.com/forum/attachment.php?attachmentid=21764&stc=1&d=1349181439

by garymunson

Look on passenger side, firewall/ inner fender liner corner; inspect the Outside Recirculate Air vacuum "motor" & vac line

http://www.supermotors.net/registry/media/767412 pic

HVAC System Vacuum Tank (plastic ball type) Location & Carbon Canister (Charcoal, Vapor, Evaporative Emission (EVAP) & Vacuum Hose Routing Video in an 86 5.0

Source: by JKossarides ("The Bronco", Jean) at http://www.supermotors.net/registry/media/742200

HVAC System Vacuum Tank (plastic ball type) Location & Diagram in 80-86 & 92-96; "...80-91 similar, except 87-early 88 w/factory air; The 80-86 vacuum tank is a plastic ball on the R wheel well..."

http://www.supermotors.net/registry/media/741015

HVAC System Vacuum Diagram in 92-96; "...80-91 similar, except 87-early 88 w/factory air..."

http://www.supermotors.net/registry/media/741015

Look under dash glove box area @ vac motors, vac lines and control panel for leaks.

Can pull lines off of control panel and test with hand held vacuum pump with gauge, aval. @ parts stores loan a tool program

HVAC System Vacuum Diagram in a 95 by Seabronc

http://broncozone.com/uploads/monthly_09_2012/post-3816-0-48521300-1346936396.jpg

Control Panel;

http://s754.photobucket.com/user/jimdog32526/media/Air%20COnditioning/WP_000383.jpg.html

"If you pull the AC controls from the dash and look on the back of the switch with OFF, you find it has a vacuum connection that is held on by 2 special washers. If the plastic peg breaks, or the washer comes off, the vacuum manifold end can pull away from the switch and cause a leak. The switch can also break causing a leak in the switch itself." by jowens1126 in a 94

 

http://s754.photobucket.com/user/jimdog32526/media/Air%20COnditioning/WP_000185.jpg.html

"Under the dash is a vacuum line bundle, it comes thru the firewall, then into a large multiport connector, then the lines go to the selector switch on the back of the control panel. The Big multiport connector could come loose and cause a leak. Its the biggest connector here with yellow lines coming off of it."

by jowens1126

http://i754.photobucket.com/albums/xx181/jimdog32526/Air%20COnditioning/WP_000382.jpg

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

Carbon Canister (Charcoal Canister, Vapor Canister, Evaporative Emission (EVAP) Canister for the Evaporative System and line to & Cruise Control sys in 86-91

Note; use fuel-rated vacuum hose for Canister purge solenoid (CanP)

http://www.fullsizebronco.com/forum/attachment.php?attachmentid=15892&d=1295451421

pic by Robert

http://rs647.pbsrc.com/albums/uu198/edaminski/96%20bronco/chacoalcanister.jpg?w=480&h=480&fit=clip

&

http://rs647.pbsrc.com/albums/uu198/edaminski/96%20bronco/P9050933.jpg?w=480&h=480&fit=clip

CanP vacuum hose to throttle body

pics by edamanski.

http://www.supermotors.net/getfile/795444/thumbnail/p6130044a.jpg

Cannister Purge Solenoid (CANP)

pic by SeattleFSB

...

http://www.supermotors.net/getfile/49966/thumbnail/halftonbooster1.jpg

& Line to & the power brake booster; Location pics in a 92

by Zach K (BurnedB, BurnedBronco, Badassbronco)

Fuel Pressure Regulator (FPR); check vacuum line, should no gas or aroma thereof in it.

Hose to Cruise Control sys in 86-91.

Leaky O-rings around the fuel injectors are allowing air to leak past the seals.

Manifold Absolute Pressure Sensor (MAP) Sensor

Location pic in mid 80s;

http://www.supermotors.net/getfile/71668/thumbnail/solenoids.jpg

the "right side" (passenger) near the EEC Test Connectors

vacuum hose; ; if good, check vacuum levels w/gauge;

because Ryan M (Fireguy50) wrote; "...The sensor changes frequency relative to intake manifold vacuum. The sensor frequency increases as vacuum increases..."http://web.archive.org/web/20120121075605/http://www.oldfuelinjection.com/index.php?p=27

Vapor Management Valve; miesk5 note; for OBD II, The vapor management valve (VMV) replaces the canister purge valve used in EEC IV; miesk5 note the Vapor Management Valve (EVAP SYS) is located on passenger side firewall, high in our 96 5.0L

http://rs647.pbsrc.com/albums/uu198/edaminski/96%20bronco/P9050934.jpg?w=480&h=480&fit=clip

Pic by edaminski in his 96 5.8

A vacuum gauge is a good low cost test and MPG helper you can spend $ on;

Gas Saver Vacuum GaugeFull swing gas saver, OEM size gauge w/panel.

  • Heavy duty, shock protected movements
  • All metal cases, wide triple chrome plated bezels
  • OEM style backlit illumination
  • Work on 12 volt neg. ground systems, 4-6-8 cylinder engines
  • Beautiful clamshell packaging
  • Unconditional 10 year warranty
Part #: PM1520

http://www.autoparts2020.com/rsdev/part_detail.jsp?PART_HDR_ID=87069

pic; "...a vacuum gauge mounted right in the dash of my truck. I use it to also help determine the load my engine is under while driving, and to estimate fuel economy..."

by William T at

http://www.fordf150.net/images/mytruck/vacgauge.jpg]http://www.fordf150.net/images/mytruck/vacgauge.jpg

__________________

 

Vacuum Diagram Color Codes: not all apply to your year

Red = Main vacuum

Green = EGR function

Orange = Heat control Valve (exhaust & intake) (AKA heat riser but more complex)

Yellow = Distributor advance

White = EGR vacuum (source)

Black = Mainly used for the Evaporative emissions control

Black = Thermactor ACV or Diverter valve

...

 

Vacuum Diagram Color Codes: not all apply to your year

Red = Main vacuum

Green = EGR function

Orange = Heat control Valve (exhaust & intake) (AKA heat riser but more complex)

Yellow = Distributor advance

White = EGR vacuum (source)

Black = Mainly used for the Evaporative emissions control

Black = Thermactor ACV or Diverter valve

Blue = Throttle Kicker control

Pink = TAD to Thermactor Air Bypass Valve (TAB or AIR BPV) /AIR Bypass (AIRB) valve

NOTE: AIR BPV is the AIR Bypass (AIRB) Valve; also called the TAB (Thermactor Air Bypass) Valve in other years/diagrams

 

See your Vacuum Diagram; not including HVAC system under hood or atop radiator suppor[t

aka Vehicle Emission Control Information (VECI), PUK (49 States) Decal, PGP (Canada) Decal

 

Vacuum Line Acronyms:

TAB is the Thermactor Air Bypass Solenoid

TAD is the Thermactor Air Diverter Solenoid

ACV (Air Control Valve) is the TAD (Thermactor Air Diverter) Valve (AIR Bypass (AIRB) and AIR Diverter (AIRD) valve combinations);

MAN VAC is Manifold Vacuum;

FPR is Fuel Pressure Regulator;

EGR is Exhaust Gas Re-circulation Valve and/ or EVR is EGR Vacuum Regulator

SOL V: Thermactor Air Diverter (TAD) Solenoid (SOL V) (AIRD) & Thermactor Air Bypass (TAB) Solenoid;

VMV is Vapor Management Valve ; located on passenger side firewall, high in our 96 5.0L; miesk5 note; for OBD II, The vapor management valve (VMV) replaces the canister purge valve used in EEC IV

VRESER is the Vacuum Reservoir Can (Tank, aka coffee can that often rusts out on bottom;

V REST on later years is Vapor Valve atop fuel tank; runs forward to Carbon Can (Carbon Canister, (Charcoal Canister, Vapor Canister, Evaporative Emission (EVAP) Canister);

CPRV is Canister Purge Solenoid Valve/ Canister Purge Solenoid (CANP); from canister to throttle body,

MAP is Manifold Absolute Pressure Sensor;

AIR BPV is the AIR Bypass (AIRB) Valve, also called the TAB (Thermactor Air Bypass) Valve;

VCKV is Vacuum Check Valve;

PCV is Positive Crankcase Ventilation Valve

MAN VAC is Manifold Vacuum

CAT is the catalytic converter

ENG is the engine

 

Vacuum Diagram Color Codes: not all apply to your year

Red = Main vacuum

Green = EGR function

Orange = Heat control Valve (exhaust & intake) (AKA heat riser but more complex) for carbureted years

Yellow = Distributor advance for earlier years

White = EGR vacuum (source)

Black = Mainly used for the Evaporative emissions control

Black = Thermactor ACV or Diverter valve

Blue = Throttle Kicker control for carburetors

Pink = TAD to Thermactor Air Bypass Valve (TAB or AIR BPV) /AIR Bypass (AIRB) valve

NOTE: AIR BPV is the AIR Bypass (AIRB) Valve; also called the TAB (Thermactor Air Bypass) Valve in other years/diagrams

 

See your Vacuum Diagram; but it does not include HVAC system under hood or atop radiator support

aka Vehicle Emission Control Information (VECI), PUK (49 States) Decal, PGP (Canada) Decal

 

Acronyms, Carbureted

(not nec. for your year/engine)

A/CL: Located in the air cleaner

A/CL DV: Air Cleaner Diverter Valve

A/CL BI MET: Air Cleaner Bi-Metallic Valve

A/CL CWM: Air Cleaner Cold Weather Modulator

ACT: Air Charge Temperature Sensor, prior to 1992

ACTS: Air Cleaner Temperature Sensor

ACV: Air Control Valve

AIR: Thermactor, short for Thermal Reactor. CA vehicles are installed with it as standard. Air Injection Reaction is what it stands for.

AIR BPV: AIR BPV is the AIR Bypass (AIRB) Valve; also called the TAB (Thermactor Air Bypass) Valve

BV: Bowl Vent (on top of the float tanks)

CARB: Carburetor

CBD: Closed Bowl Distributor

CPRV: Canister Purge Valve

DIST: Distributor

DPFE: Differential Pressure Feedback

DV-TW:Two Way Delay Valve

EFCA: Electronic Fuel Control Assembly/ (Fuel Pressure Regulator (FPR)

EGR: Exhaust Gas Recirculation

EGRC/EGRV: EGR Vent/EGR Control

EXH HCV: Exhaust Heat Control Valve

EVP: EGR Valve Position

EGR: Valve Position

EVR: EGR Vacuum Regulator; also called EGR Vacuum Solenoid

FLTR: Filter

FPR: Fuel Pressure Regulator (check vacuum line)

HEAT VLV INT: Heat Vacuum Control Valve Intake, (next to carb)

HICV: Hot Idle Control Valve

IAT: Intake Air Temperature Sensor (Air Charge Temperature (ACT), prior to 1992

IVV: Thermactor Idle Vacuum Valve

LCV: EGR Load Control

MAN VAC: Manifold vacuum-Vacuum source; usually ref. to as Vacuum Tree atop intake manifold]

MAP: Manifold Absolute Pressure

PCV: Positive Crankcase Ventilation

PURGE: Vapor Canister Purge Valve

PV: Ported Vacuum

PVS: Ported Vacuum Switch (PVS) Valve

S: Spark port

SA-FV: Separator Assembly Fuel/Vacuum

SOLV: Thermactor Solenoid Valve

SV CBV: Carborator Fuel Bowl Solenoid Vent Valve

TCAC: Thermostatically Controlled Air Cleaner

TCP: Temperature Compensated Accelerator Pump

TK: Throttle Kicker

TVS: Throttle Valve Solenoid (aka Solepot, Dashpot)

or

TVS: Temperature Vacuum Switch

TVV: Thermal Vacuum Valve

or, TVV: Thermostatic Vacuum Valve (aka Ported Vacuum Switches; Thermal Vacuum Valve)

VAC: Vacuum

VCKV: Vacuum Check Valve

VCV: Vacuum Control Valve

VDV: Vacuum Delay Valve

V CK V or VCV: Vacuum Check Valve

VOTM: Vacuum Operated Throttle Modulator

VRDV: Distributor Vacuum Delay Valve (VDV, VRDV, DV-TW)

VRDV: Vacuum Delay Valve (VDV, VRDV, DV-TW)

VRESER: Vacuum Reservoir (coffee can style in earlier years; replaced by plastic style)

VRESV REST: on earlier years such as SEABRONC's 83 is a Vacuum Restictor/delay valve, it delays vacuum for a certain amount of time

VRV: Vacuum Regulator Valve

WOT: Wide Open Throttle Valve

...

 

also, a Vacuum Gauge Diagnosis in 96 Bronco Workshop Manual by Ford via

http://www.diesel-dave.com/vehic/manual/stj/stj30013.htm%5Dhttp://www.diesel-dave.com/vehic/manual/stj/stj30013.htm"]http://www.diesel-dave.com/vehic/manual/stj/stj30013.htm]http://www.diesel-dave.com/vehic/manual/stj/stj30013.htm

Edited by miesk5
harness pics couldn't be added due to riggin error messages

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I'm using the Haynes Bronco/Truck manual. I do have a vacuum gauge (hand held) that seems to be working fine.

 

 

I will start with vacuum check when idle and report back. Is there a chance that the vacuum is OK at idle, but leaks at that 2700RPM level?

I did replace the O2 sensor. As far as i can see or tell, there was only one to replace, although i think there must have been some variants that used 2 or more. Is there any way to confirm that there is only supposed to be one, perhaps by VIN?

 

OK, more results to come. Thanks.

 

Quick edit: it was suggested to me that the vacuum lines may not necessarily leak, but they might have weakened to the point where they are collapsing shut and thus cutting off the vacuum prematurely, Is this something that anyone has heard of?

Edited by James Kiehl

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yo JIM,

ok, thanks.

Someimes Haynes and Chilton group trucks and Broncos systems with that of cars; Such as including a 90's car EGR sys ( say a pfe type) w/ Bronco/F Series EVP System 9F483 (9H473 9G428 )
(Tomco is confusing)

 

 

VACUUM PROBLEMS

We have looked at the EGR solenoids and the EGR valve and EVP for testing and problems. But there could be a low vacuum problem. Check

the source vacuum and make sure there are no leaks in the line to the solenoid. Also make sure you check the line to the EGR valve itself.

In many cases the systems we have been looking at start to open the EGR valve at 1 to 1.5 in HG and only need a maximum of 4 in HG to

open fully. When checking to see if opening an EGR valve will make a difference in RPM, we hook up a vacuum pump and apply 15 inches of vacuum. This is almost 4 times as much vacuum as the EGR valve will see under normal operating conditions. This might cause us to miss a partially clogged or sticking EGR valve. Apply the vacuum to the valve that it will see under normal  operation to test it more accurately.

http://www.tomco-inc.com/Tech_Tips/ttt32.pdf

 

 

You can "rent" (w/ a fully refundable deposit) a hand operated vacuum pump w/bulti-in pump at most parts stores.

 

 

  • Place the Bronco in "Park" and set the emergency brake. Start the Bronco & allow the Bronco to warm up for 10 minutes.

  • 2

    Open the hood of the Bronco and locate the EGR valve. The valve is located on the intake manifold and is a small, circular metal valve. Locate the plunger mechanism on the outside of the valve; this controls the direction of the exhaust.

  •  
  • 3

    Instruct an assistant to rev the engineicon1.png of the Bronco as you watch the plunger mechanism. The plunger should open and close quickly. If the plunger fails to open and close quickly and smoothly, the valve needs to be cleaned or replaced as exhaust is not being redirected properly.



  • Read more: http://www.ehow.com/how_6345967_test-bronco-egr-valves.html#ixzz2hFuVtR4a

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Ok, made a little more progress. I did a voltage check across the EGR solenoid. At KOEO, it is supposed to read 10.5+ V across the red and brown/pink stripe wire. The red comes off of the power and the BR/pnk returns to pin 33, EVP.

 

When is disconnected the wires and tested open circuit, I noticed this:

 

V from red to BR/pnk - reads 5V on the 50V scale and close to 2 V on the 10V scale.

V from red to chassis - 10.5 V

R from red to chassis - spikes ohm meter past 0

V from BR/pnk to chassis -0 V

R from BR/pnk to chassis - close to 0 ohms (reads less than 1) but does not spike it past 0 like red-to-chassis.

 

I think the problem has to be BR/pnk - to - EEC.

 

EEC module is new, so I think the wiring is bad, not the module, but I'm open to suggestions.

 

I'll test the BR/pnk section between solenoid and EEC harness.

 

Any other thoughts?

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yo James,

 

Check for what Ford describes as "terminal back-out" in many Pin-Point Tests 

Check EEC system wiring harness for proper connections, bent or broken pins, corrosion, loose wires, proper routing, etc.

 

GL!

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Ok, update:

 

KOEO/continuous/run

11/11/11

 

All clear. I ended up thinking that maybe the EVP piston from the new aftermarket unit might sit differently than the original. I kept the old one around, so I popped it back on and it looks like the newer unit was sitting with enough extra resistance to show a code 34. Now that the original is back in and the seperate, original problem of bad Vref is solved (new EEC), I am reading all clear on all codes.

 

Thanks for the help, will update with emissions test results (I'm not out of the woods just yet).

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