Hi,
I have a 92 Z28 5.7.

The Check Engine Soon light will come on, whenever I get on the freeway.
I checked the code and it's a 32, which is an EGR error.

From searching the forum, I've read it could be either the EGR valve itself, or also some vacuum lines.

Where is the EGR valve? Does anyone have a pic of it on the car?
Also what vacuum lines should I be checking?

Could either the valve or the lines cause it to sort of miss when idling? I've noticed that after it's been driven for awhile, that at a stop light it runs a little rough.

Thanks!
Chris

 

Its right on top of the intake manifold but under the plenum towards the rear. You need to disassemble the TPI to get at it. More than likely the solenoid is bad and they are no longer available. It may be best to have it deleted from the ECM/Memcal programming so that it doesn't operate or set error codes. PM me if you are interested in that. There may be other causes but this is the most common.

 

ah crap, it's a common part that goes bad and you can't get a replacement anymore? that stinks.

Is there a way to test the solenoid?

Could the rough idle even be caused by the EGR system?

I also notice that the car at a light, will hesitate just slightly when taking off. Like it has to think if it wants to go or not. Not sure if I'm explaining this correctly, but when I take my foot of the brake and on then move to the gas there is a like a split second when it almost feels like the car died but it then goes.

 

Both symptoms could be caused by the EGR stuck open. Not sure there is a test.

 

There's a link to GM test for all codes PDF in the thread below. It is a common problem even with good parts. But your's actually sounds like it is sticking open. It will probably need to be replaced and the passages cleaned.

https://www.thirdgen.org/forums/dfi-...code-32-a.html

 

32 means the ecm doesnt see a vacuum drop when the solenoid is opened/on.

If the EGR valve wasnt hidden, you can just push the diaphragm up and see if the engine stumbles at idle. Since you cant push on it, you can use a vacuum pump. If it doesnt stumble, could be bad egr valve or plugged up passages in manifold.(other it could not be closing/stuck)
You can check the solenoid with 12v, off it doesnt let vacuum past, open it does.

 

http://www.youtube.com/watch?v=x1MyOODy9W0

 

TPI EGR doesn't work quite same way as TBI, it gets its signal of trouble from a temperature diagnostic switch. If it doesn't see temp increase when EGR is supposed to open or decrease when should be closed you get a code 32. see drawing below.

 

so there is a switch there too.
OK, so hopefully it's not the solenoid, since you can't get that anymore. Is the switch still available?

 

Actually I think that is the part of the solenoid that is no longer available. I have read that it is available for the 90-91 corvettes and is same except wire is shorter. search 3GO for code 32 and you should find info.

 

92 doesn't use the temp sensor on the EGR valve.
i believe 89 was the last year for the temp sensor on V8 TPI thirdgens.
the ECM looks for minor changes in either MAP or BLM/INT readings by commanding the EGR valve on and off during cruise above about 45 MPH.

 

Denn_shan is correct. they operate differently it seems. MAF cars call it a vacuum sensor diagnostic connection and MAP cars call it exhaust gas recirculation solenoid connection in the wiring diagrams. So just on that basis it does appear they do the EGR failure sensing differently. Hence, different hardware. AND the MAP EGR solenoid on your car is the hard piece to find.

 

Figures. lol

 

Actually, if you don't mind modding the wire harness or building a plug adapter to the older style Weather-Pak connector, you should be able to use an EGR vacuum solenoid from a pickup/Suburban from '88-'95:

STANDARD MOTOR PRODUCTS VS-12 (OEM Part #14102002, 214329)

 

I believe I read that the 90-91 Corvette was exactly the same except the wire was a little short but if you ran it a different way it would reach.