[bob22]

Did you replace the valve and the solenoid? They have to be done together as they are calibrated from factory to work together. Could be solenoid is faulty if you say valve works?

[Gerry G]

The pinging is caused by a lean condition. This may also be a symptom of a weak O2 sensor. The two are related in the
manner that the ODB (on board diagnostics) determines an egr failure. After the engine has warmed up, the odb computer
will open the egr valve. This will cause a lean condition that the O2 sensor should detect. If the reading from the O2 sensor
does not change the odb assumes that the egr is failing to open and throws an egr code. My advice is to change out the
O2 sensor (upstream - before the catalytic converter) and see if that stops the pinging and the egr code. There may also
be a leak in one of the vacuum hoses or egr tubes that is causing additional air to get into the intake plenum.

Hope this helps,

Gerry G.

[t2erns]

If you were a registered user, you would not be seeing this!

i guess your problem is not with the egr itself, this is an exhaust back-pressure type egr and it's working as per your test description. if you disconnect the solenoid you will open directly the bleed valve in the transducer (disregarding the exhaust back pressure) thus the vacuum will be directly applied to vac motor thus opening its pintle (poppet valve) that will allow flow of the exh gas. i guess your problem is more on the low exhaust back pressure. have you modified your exhaust? have you checked the back pressure hose

This post has been edited by t2erns: 10 July 2007 - 05:23 AM

[t2erns]

ok pat here's how the egr works:
When the PCM energizes the solenoid, vacuum does not reach the transducer (the round part below the solenoid). Vacuum flows to the transducer when the PCM de-energizes the solenoid. When exhaust system back-pressure becomes high
enough, it fully closes a bleed valve in the transducer. When the PCM de-energizes the solenoid and back-pressure closes the transducer bleed valve, vacuum flows through the transducer to operate the EGR valve. De-energizing the solenoid, but not fully closing the transducer bleed hole (because of low back-pressure), varies the strength of vacuum applied to the EGR
valve. Varying the strength of the vacuum changes the amount of EGR supplied to the engine. This provides the correct amount of exhaust gas recirculation for different operating conditions. This system does not allow EGR at idle. A failed or malfunctioning EGR system can cause engine spark knock, sags or hesitation, rough idle, engine stalling and increased emissions.
EGR gas flow test:
.connect a vac hand pump to the EGR valve vac motor. w/ engine running at idle slowly apply vac, engine rpm should drop or engine may stall.
EGR system test:
allow engine to run to fully warm-up (ect temp over 150 deg F) with transmission in neutral and throttle closed, abruptly accelerate the engine approx 2000 rpm but not over 3000 rpm. the egr stem should move when accelerating the engine (groove of the egr stem should change) repeat test several times. if the stem moves, the control system is working normally.

[t2erns]

now i guess you have a wiring issue, what year is the car, the ground side of the solenoid is possibly shorted to ground that even the computer is cutting it off it's always grounded. i'm sure you can easily checked that if you have an ohmeter. remember solenoid "on" no vac to egr valve.

[t2erns]

patcal, on Jul 12 2007, 11:26 PM, said:

Well, the scanner shows no codes until I unplug the solenoid. I am really confused. With the EGR not working at all & the car pinging you would think a code would set.

Pat

pat as long as the wirings are intact (egr solenoid to the pcm) i guess it will not throw the code if the ground wire is grounded the fact that the said wire is shorted to ground the solenoid wont turn-off even if the pcm is cutting it's ground (bec ground is always there that keeps the solenoid energized) it's just my 2 cents if its an older car (newer models have some rationality checks for each circuit).BTW have you checked if you're getting some lean codes, is your scanner capable of reading fuel trims, injector pulse width and oxygen sensor readings so we can diagnose it further? is this car the one in your signature, what's the engine size, i'd like to check if there's a service bulletin for this car.

This post has been edited by t2erns: 12 July 2007 - 11:49 PM

[t2erns]

pat i'm a little bit confused about your pcm pin-out, i have here a powertrain manual with a schematic diag. for your car. the ground wire for the solenoid is from pin 40 of the pcm (could you re-check that one on your diag) and the 12v supply is from the asd circuit. now disconnect both pcm and solenoid connectors, you should not get a continuity to ground, if it shows continuity then you have nailed the problem (the ground wire is shorted to ground) as for the asd circuit it's normal to have continuity to ground since the ckt passes to diff sensors (oxygen sensor, fuel injectors, ign coil, etc which have their circuit to ground).


"wanted to say, I really appreciate all your help. I think you have gone above & beyond what most forum dwellers would do".


the signature have your answer... cheers

This post has been edited by t2erns: 13 July 2007 - 05:49 AM

[t2erns]

ok now i know your diag is correct (seems only typing error when you posted pin 60 for the solenoid control ckt).

[t2erns]

if you're positive that the pcm is not cutting off the ground (solenoid control pin 40) then i'm also inclined to say that the pcm is defective.