Can not get egr vacuum solenoid or Air management solenoids to work.. PLZ help

Sep 10, 2003
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#1
Here is my problem i have a 90 GT 5.0. Mostly stock right now with bolt on's pullys, intake, exhaust.. I live in california and have to pass the smog test out here. I pulled codes and they say the air management valve and the egr has lack of flow. I have replaced the 3 solenoids on the pass shock tower, checked all vacuum lines and all are good..If i put vacuum to the egr the engine stubles so i know the erg valve is good. I have tested all sensors and they are with in spec. TPS, MAF, Egr Position sensor.. If i put a vacuum guage on the line comming from the egr vacuum solenoid and snap the throttle and get no vacuum what so ever.. I should have atleast 5 hg.. right
I have check the ref voltages to all the solenoids and all at 12 volts.. I pinned the otherside to the computer and they all ohm out fine... I also just cleaned/replaced all the grounds in the car. I am lost on what i should do next i have searched on stangnet for the last 2 weeks and tried every little thing i have read and no luck... Other than that the car runs well for the stock motor. I have noticed some pinging when i get on it latly i figure it is because of the egr valve not working. also i have no check engine lights on. any help would be greatly appriciated. I just need to pass smog one more time then i can toss in my 331... :bang:
 
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PNY PWR

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#2
Is your smog pump pumping? On the EGR, it's probably carboned up. You might try pulling the EGR, TB, and EGR spacer. They do get pretty clogged. All it would cost is some gaskets. You can just clean everything up real good and put it back together.
 
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The pump is pumping like it is supposed to. I just had the upper intake off and cleaned the heck out of it. the egr is just not getting the vacuum to it to open. also i forgot to mention that i also ceaned all connectors the 2 salt and pepper shaker ones, the computer, and all sensor connectors.. Does anyone know when i can possible find a good flow chart for that i have the chiltons and look at the haynes no luck.
 

HISSIN50

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mustang331strok said:
Does anyone know when i can possible find a good flow chart for that
flow chart for what? vac line chart? im lost but want to help ya out. :)

also, if you are checking for vac created/allowed from the EVR, snapping the throttle might not be the best test. EGR opens at, amongst other times, steady cruise.

good luck.
 
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As far as the chart i have the vacuum and the wiring chart.. I am basicly looking for the diagnostic flow chart to start eliminating possible problems.. yes no type.. If the voltage is at this go to this step if it isnt then check this sort of thing.. Like i said it must be something wrong if it is both the egr vacuum solenoid and the air management solenoids that are not working..
 
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Yesterday i cleared all codes so nothing was in the computer and it had to relearn everything. and i drove it around today i pulled codes and the KOER codes are back they are 33 and 44.. still the egr and thermactor valve issues..
Anyone have any other ideas i dont know what is next.. could my car possibly not be going into closed loop mode.. if so why not any help would be greatly appriciated..
 
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I am running the stock 192 i think it is.. maybe 195 not sure what factory is at.. i am thinking it is now my COOLANT TEMPERATURE SENSOR that goes to the computer.. whats the best way to test this it has a 2 plug pin and is ontop of the intake. In the black water lines that run under the upper intake..
 

HISSIN50

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Jrichker has posted the ECT and ACT codes in here before - a search will reveal them. good luck.
 

jrichker

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#11
Code 33 - Insufficient EGR flow detected.
Look for vacuum leaks, cracked vacuum lines. Check to see if you have 10” of vacuum at the EGR vacuum connection. Look for electrical signal at the vacuum regulator solenoid valves located on the rear of the passenger side wheel well. Using a test light across the electrical connector, it should flicker as the electrical signal flickers. Remember that the computer does not source any power, but provides the ground necessary to complete the circuit. That means one side of the circuit will always be hot, and the other side will go to ground or below 1 volt as the computer switches on that circuit.

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host)

http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

http://www.veryuseful.com/mustang/tech/engine/images/88-91eecPinout.gif


Codes 94 & 44 - AIR system inoperative - Air Injection
Check vacuum lines for leaks, & cracks. Disconnect the big hose from smog pump: with the engine running you should feel air output. Reconnect the smog pump hose & apply vacuum to the first vacuum controlled valve: Its purpose is to either dump the pump's output to the atmosphere or pass it to the next valve. The next vacuum controlled valve directs the air to either the cylinder heads when the engine is cold or to the catalytic converter when the engine is warm. Disconnect the big hoses from the back side of the vacuum controlled valve and start the engine. Apply vacuum to the valve and see if the airflow changes from one hose to the next.

The two electrical controlled vacuum valves mounted on the rear of the passenger side wheelwell turn the vacuum on & off under computer control. Check to see that both valves have +12 volts on the red wire. Then ground the white/red wire and the first solenoid should open and pass vacuum. Do the same thing to the light green/black wire on the second solenoid and it should open and pass vacuum.

Remember that the computer does not source any power to actuators, relays or injectors, but provides the ground necessary to complete the circuit. That means one side of the circuit will always be hot, and the other side will go to ground or below 1 volt as the computer switches on that circuit.

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host)

http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

http://www.veryuseful.com/mustang/tech/engine/images/88-91eecPinout.gif
 
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I did the test light test across the solenoid connectors and there was no light. So this means the computer is not grounding the circuit.. right? On all 3 valves it does this.. When should the air thermactor valve try to open.. same time as the egr? if the computer is not telling the solenoids to open what would cause that .. Could i hook a dvom between the side that the computer grounds and then check to see the resistance to ground? possible bad computer ground?? if so where would be a good place to ground it again?

Thanks again for everyone help on this.. :hail2:
 

jrichker

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#13
mustang331strok said:
I did the test light test across the solenoid connectors and there was no light. So this means the computer is not grounding the circuit.. right? On all 3 valves it does this.. When should the air thermactor valve try to open.. same time as the egr? if the computer is not telling the solenoids to open what would cause that .. Could i hook a dvom between the side that the computer grounds and then check to see the resistance to ground? possible bad computer ground?? if so where would be a good place to ground it again?

Thanks again for everyone help on this.. :hail2:
The computer supplies the ground to complete the circuit. I would do a Key On Engine On test (jumper computer to dump codes) and watch for it to flash the test lights. This test makes all the actuators activate and is the easy way to determine if the solenoids are being triggered.

EGR & Thermactor systems are two different & independent systems. One may not operate at the same time as the other.

Pull the computer connector off & check the resistance between the actuator wiring under the hood & the pins on the computer. Use the diagrams I previously posted for help.

Here's a book that will get you started with how the Ford electronic engine control or "computer" works.

Ford Fuel Injection & Electronic Engine Control 1988-1993 by Charles Probst :ISBN 0-8376-0301-3.

It's about $20 from Borders.com see http://www.amazon.com/ . Select boo...very good, and I found it to be very helpful.
 
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the KOER test the test light did not flicker. i went down and ordered the book and should have it in 7 days.. as far as the computer grounds any ideas.. I mean if the comp has a bad ground that would make grounding the solenoids only part way correct..
 

HISSIN50

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so you were not able to run codes? that is how i read ya' (sorry if im reading ya wrong). if so, i might check the puter ground and EEC relay. otherwise, sounds like puter issues.

good luck.
 
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i cleared codes and then ran the KOER test and watched the test light to see if it ever came on while it was checking for codes.. it never did but i still got the code 33 and 44.. where are the grounds to the computer?
 

jrichker

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#17
If the computer grounds were bad, the engine would not run.

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host)

http://www.veryuseful.com/mustang/tech/engine/images/88-91eecPinout.gif

Using the diagram from the link I posted, main power ground is pins on 40 & 60. The computer uses these grounds to supply ground for everything it operates. That includes fuel injectors, actuators, relays and sensors.

Check the wiring between the computer and the actuators. Use the ECC diagram from above to locate the pins & wire colors. You should see less than 1 ohm between the pin on the computer & the same color wire on the actuator.
 

PNY PWR

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#18
My concern is if the cose 33 is saying the egr is not closing properly then why not replace or reinspect the egr? Get the AIR assembly from a salvage yard and swap it out, see if that works for the other code.
 
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okay here is what i have now.. Tested vacuum going to the egr solenoid it is about 18. Ran the KOER with a scan tool with egr vacuum line dissconected from egr and vacuum guage attached the guage never moved.. So i tried again but with out vacuum guage and just put my finger over the line i could feel very minamal amount of vacuum.. also it seemed to be pulsing.. Next i hooked the guage back up and grounded the solenoid my self and i got full vacuum to the guage.. WTF so now i know it is the computer not grounding the other side of the solenoid.. What next replace the computer... i also checked the resistance of both that power and ground wires and they are both very low.. this was from the computer to the solenoid itself... any new ideas from this one
 

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