Renoman

I had a code 32 pop up a few days ago. I discovered I had an intermittent connection at the EGR solenoid. What I found interesting is the solenoid is normally open at rest, meaning vacuum can pass through it if it is not energized with 12vdc. On the bench, when I apply 12vdc I hear the solenoid click and I cannot pass vacuum through it. This seem contradictory to how I thought the solenoid operated. So it seems when the car is started, 12vdc is applied to the solenoid the vacuum ports are closed to prevent vacuum from going to the EGR valve. So if the solenoid is bad it seems that the EGR valve may open at idle because vacuum is applied to it when it's not supposed to. My service manual reads "The ECM turns the solenoid "OFF" to allow vacuum to pass to the EGR and turns the solenoid "ON" to prohibit EGR operation" This is exactly what I discovered while troubleshooting my car today. Any replies are appreciated.

Art

Tuned Performance

iTrader: (92)

you have the egr solenoid operation correct. the code 32 is ofter caused bye a bad egr temp sensor. Zip corvette has them or it can be disabled in the ecms tune.

Renoman

I believe I do have a ground in the egr temp switch. I was actually measuring voltages at ecm connector and observed 0 volts at terminal C15 both with the ignition on and with the engine running. I am having a surging problem and removed the egr. I notice the temp switch was loose so I tightened it up. I notice a wire coming out the end of it or something. After tightening it I may inadvertently grounded it. I'm going to check it disconnected for a ground. If there is one, I'll have to remove the plenum and check the temp switch. I have been doing a lot of troubleshooting trying to eliminate the surging I'm experiencing. Thank you for your prompt reply.

Tuned Performance

iTrader: (92)

With the code 32 set you will be in limp home mode . The pintle in the temp switch should not move but you can adjust it and put on a jam nut. if you don't have 12v at c15 koeo or running sounds like the ecm is faulty.

Renoman

I'll go out and see if I have 12vdc at C15 with the connector unplugged. I would think I would not see voltage at C15 if the sensor was shorted to ground.

Tuned Performance

iTrader: (92)

You can also turn your key on and check for the 12v at the temp sensor pigtail.
If the switch is closed on start up or does not close when the operating parameters are met, this code will be set. So using a ohm meter on the pigtail to ground the sensor is normally open. If you do need a ecm I have a few send me a pm. Or if you want to update to 89 programing and get rid of the code 32 I can assist with that aswell

IROCU2

Tune,

Sorry to hi jack this thread but I need your help. I have a 87 IROC 5.7 that is experiencing rough idle ad surging. It currently has a code 33 present. I unplugged the MAF and it made not different at all. I am thinking that I need to replace at the least my injectors (yes I have the Multitec junk) and my ECM. I currently have the 1227165 ECM. Do you by any chance ad a spare. If so how much would you let it go for?

Tuned Performance

iTrader: (92)

I do have only 1 1227165 ecm left for $60 shipped pm me for paypal info if your interested.
I'm sure you went through the testing on the code 33 first.
https://www.thirdgen.org/forums/tpi/...-pls-help.html

Renoman

I was reading about the egr valve in my service manual. I'll be removing the plenum if the egr temp switch is grounded and try to adjust it since I had screwed the wire in further when I R&R'd it last week. I attribute my code 32 to the last thing I did on the car since I didn't have the code before. In the service manual it mentions negative and positive backpressure and ported egr valves. I just want to confirm that what I have is a ported egr since the vacuum source is coming from the throttle body ported vacuum connection and not direct manifold vacuum. It's an 88 TPI, however I did assemble it from different sources but did my best to ensure the parts were from an 88 Camaro TPI or compatible components.

Tuned Performance

iTrader: (92)

If you don't want to fool around trying to adjust the temp sensor. This is the only source I know that has them.
http://www.zip-corvette.com/ProductD...GR-SR&CTitle=&

Renoman

Something I find annoying in the Service Manual are contradictions in operation. I don't know if it's just my interpretation of what is written but here is a quote from the manual. "During cold operation and at idle, the solenoid circuit is not grounded by the ECM. This blocks vacuum to the EGR valve". The next paragraph is written "Grounding the ALDL diagnostic "test" terminal, with the ignition "ON" and the engine not running will energize the solenoid and block vacuum to the EGR valve" To me both paragraphs contradict each other. The first one says that an un-energized solenoid blocks vacuum and the next one says the energized solenoid blocks vacuum. From what I've been able to determine; the operation is like I observed in my first post or what is in the second paragraph. Go figure.

Tuned Performance

iTrader: (92)

yeh, that was not described correct lol, not the first error in a helm.

Renoman

I found several interesting links

http://chevythunder.com/since_its_inception_in_1985.htm

http://chevythunder.com/fuel%20injec...temp%20sw..htm

http://www.ebay.com/itm/390476486673...84.m1423.l2649

http://www.ebay.com/itm/371001331298...84.m1423.l2649

http://tech.corvettecentral.com/2012...egr-diagnosis/

See post 53 https://www.thirdgen.org/forums/tpi/...sor-has-2.html

Renoman

Well I removed the plenum and removed the temp switch. It was in short or grounded mode. That must of happened when I screwed it in further thinking it was loose. I re-adjusted the pintle and checked it with a meter while heating the sensor on the stove. I could get it to close pretty quickly when heated but that seemed like it might close simply with engine heat. So I backed it out a little more so it takes about 8 seconds to come on, maybe 10. I used some thread locker on the threads an attached the wire to the plastic look on the fuel rail. I road tested it after I cleared the codes. Drove it about 20 miles, seems ok, no check engine. Runs in closed loop at speed, open loop at idle. Seems to run better but still chasing the surging thing even though it hasn't done it as bad lately. I had noticed earlier when testing ecm voltages that the carbon canister relay voltage was 0 volts at idle. The manual says it should be 12vdc. I have voltage at the canister relay. I'll check that out next.