Cuervete

So I happen to have a code 32 in my 86 Corvette. "Exhaust Gas Recirculation Circuit". This is what happens:1) I start the car from cold, 2) just after start I see RPMs going up to 1200, 3) at that moment the CEL comes on, 4) RPMs drop to 900 and eventually to 600, 5) CEL stays on for the rest of the drive. If the engine is warm and I restart the car, there is no CEL. So CEL doesn't come on if the engine is warm.

Got the EGR system tested. The valve was not opening. Changed the EGR valve. Light comes on after a cold start and stays on for the rest of the drive. Light won't come on if the engine is warm. Result= Several bucks down the toilet changing the EGR valve for nothing.

Any ideas of what is going on here?

Thanks.

Cliff Harris

The ECM does two separate tests on the EGR system to verify that it is working. Unfortunately the programmers didn't differentiate between the two tests so you can't tell which problem caused the error code (except by the symptoms).

Background info: The ECM commands the EGR solenoid to open. It is mounted on the thermostat housing and gets ported vacuum from the throttle body. It feeds this vacuum to the EGR valve to cause it to open. There is an EGR pipe on the passenger side of the engine that goes from the rear of the exhaust manifold over the valve cover to the intake manifold where the EGR passages are located. There is an EGR temperature switch located in this pipe. The EGR passages go through small tubes (about 1/2" diameter) in both of the runner assemblies. One side goes through the plenum into the back of the throttle body. The other side goes to two holes in the plenum below the throttle body bores.

The first way to get an error Code 32: When the engine is first started the ECM tests the EGR switch to see if it's closed. It only closes when it sees hot exhaust gases in the EGR pipe, so being closed when the engine is cold means the switch is bad or the wiring is shorted to ground. This test is NOT done if the engine is hot at startup.

Second way to get error Code 32: When the ECM sees that certain qualifying conditions are met (like coolant temperature above a certain value, engine running time, speed, etc.) it commands EGR by turning on the EGR solenoid. The solenoid feeds vacuum to the EGR valve, which opens and applies exhaust gases into the plenum. When that happens, the EGR switch sees hot exhaust gases in the EGR pipe and closes, grounding the EGR switch circuit. This switch closure is sent to the ECM. If the ECM does NOT see this ground after it commands EGR then it sets error Code 32. Usually you will see the Service Engine Soon light come on for no apparent reason as you're cruising along. If you shut off the engine the SES light will not be on when you restart but it will come on again after you drive for a while.

It's pretty obvious from your symptoms that you have the first problem. Check your EGR switch. It's on top of the EGR pipe next to the distributor on the passenger side. In many cases the ceramic part of the switch breaks. The wire also is a problem because it gets a lot of stress because of the location and the way it comes out of the top of the switch. You happen to have this problem at a good time. The EGR switches were not available for a while, but now there is a company that is making them again. About $60 (which is a LOT more than GM was charging for them).

These parts are available at all the regular Corvette parts suppliers. Here's a pic of the switch:



It's possible that the EGR switch wire is shorted to ground. Try unplugging the connector (located down behind the distributor -- good luck with that -- it's REALLY hard to get to and also hard to disconnect). It looks exactly like the EST connector or O2 sensor connector. See if your error Code 32 goes away with it unplugged.

RetiredSFC 97

I agree with the above. Mine was coming on at warm temp/cruise speeds. (the second symptom) And the egr just needed cleaning but I changed it out anyway.

3D87C4

Fortunately they are selling the temp switches again---they were unavailable when I got my Vette. I resolved my code 32 by adjusting the temp switch:

http://forums.corvetteforum.com/c4-g...djustment.html

You can give this a try with the confidence of knowing you can buy a replacement if the wire breaks.

srayney

Does anyone have a pic of the connector? I bought one of the new switches, but don't see a connector like the one on the part behind the distributor. Unfortunately, my Vette caught fire, the harness replaced, and I never got to see what the original connector looked like. I have an empty connector behind the distributor, but it does not match the plug on the new part.

Thanks in advance...Steve

Cruisinfanatic

I did the same thing as the OP. Ended up buying the switch too and now all is well

70ZZ3 96LT4

My very first check engine light in my 1985 was a code 32. Like others have mentioned, the replacement of the temp switch fixed the problem. I checked/removed/cleaned the EGR valve and I am still using it. The first new temp switch I installed I broke the ceramic around the top and had to buy another one. Was very careful with the next instllation. This was back in about 1993, no problems since with a code 32.

sailorsteve

And the moral is, when you get a code referencing a sensor, don't automatically assume the sensor is the culprit. Use the flow chart in the FSM, if necessary.

Cuervete

Things are getting worse and I haven't had time to change the EGR Temp. sensor. Now when I start the car it has a pretty rough idle. Rough rough, baby, and with and without CEL. I even see the an explosion of colors in the digital dash with all lights coming on some times. Does anyone here has a pic of where tf is the EGR temp. sensor located in the engine?????

Thanks

AGENT 86

Follow the EGR exhaust tube from passenger side exhaust manifold to intake base. It's a single wire switch mounted where tube meets intake.

3D87C4

This will get you in the vicinity:

Cuervete

Thanks a lot!
I've looked at the connection of the wire with the upper ceramic part of the sensor and the plastic covering the wire is worn. Actually the wire can be turned way too much around the sensor head, which I guess means that it may be partially broken at that place.

Now I wonder what one can do if one is trying to take the sensor out but it does not turn anything even if one applies a good amount of torque. I'm worried about breaking the EGR pipe! Any ideas? I was thinking of leaving the sensor as is and giving more consistency to the broken wire by using a tin welder, but I'm concerned about other people here who have said that messing with it may change the resistance and the overall response of the sensor.

All ideas are welcome.

65Z01

Spray a little PB Blaster onto the base of the sensor threads and let stand over night.

Cuervete

Guys,
allright, I can remove the EGR temp. sensor head BUT the connector on the firewall is very difficult to handle. Therefore I can't remove the f... EGR temperature sensor. Do you guys know of any trick to disconnect the sensor from its end at the firewall???

I have read already all those "Oh Good luck with that" or "It's very hard to get to..." it would be great to have a practical method for removing the connector without having to remove the distributor (which is something I DO want to avoid).

Thanks as always.

3D87C4

I disconnected mine ('87) when I adjusted it. There's no trick---there aren't any catches or anything holding it closed---it's just hard to reach. I recall getting my hand on it and pulling it appart with a finger or two on each half so's not to put any strain on the wire. Getting it back together was harder with my big hands but I got it done eventually.

Good luck,

Wayne

Chewch87

I Had the same issue with my 87....the ceramic around the temp switch was cracked and the wire was lose.....Rather than go thru the hastle of changing it off...I did a "Rube Goldberg" and used an epoxy puty to set & stabilize the wire and havent had any problems since going on two years now..... and along with a new asbestos EGR pipe wrap.... It actually looks pretty good too!~!

Cuervete

Damn! I will have to wait to have the replacement in my hands and see how the connector works, because it looks daunting when I look at the pics and when I see it sitting in there. It seems to have many clips around. Do you remember how did you actually take it out?

Who the F... was the guy who designed that thing to be so damn deep in there? I mean, I'm sure he got an academy award or something like that for such a big favor to mankind.

Cuervete

I'm afraid that my wire may be cracked.

3D87C4

I think the '86 and '87 are the same. I was thinking about it while the computer was booting and here's what I recall:

I reached down along the wire with my left hand. Secured the switch side of the connector between my pinky, ring finger, and palm then grabbed the other half with my thumb, index and middle fingers and applied a seperating force by extending the thumb, index, middle finger combination. Simply pulled the two halves appart---no latches, tabs, etc.

I was surprised it was that simple. It certainly looks more complicated. Getting it back together was the reverse, but was harder to line everything up due to the awkward reach, limited space, and having to do it by feel.

Cuervete

I don't know the size of your hands, but I can only reach it with two fingers at most. We are neighbors! I'm in Palo Alto