I've been having stumbling/drivability problems with my 87 305 TPI engine. I believe I've traced it to either a bad EGR valve, or EGR temp sensor.

There is a ton of info here about the EGR valve, but just can't seem to find the answer to my question by searching.

I disconnected the EGR temp switch lead and my problem seems to go away. Does this mean I have a bad EGR valve, or EGR temp sensor? Both parts were new only 2 years ago and 10k miles. Both are GM parts.

 

That switch is the EGR temperature diagnostic switch and sends a signal to the ECM. Have you found the code 32 troubleshooting chart that has been posted on the board several times in the past. It will help you diagnose your problem. Have you also checked the EGR solenoid wiring and vacuum lines (clean them out)?

 

The solenoid checks out good, and the vac lines are good and tightly connected.

I have no trouble codes at all, and have done a scan with my Auto X-Ray unit and I can't really see any glaring problems in the data collected. The problem just seemed to go away with the temp sensor wire disconnected.

I'm wondering what it might hurt to run with the wire disconnected short term/long term?

 

AFAIK, the only problem you might have is setting a '32' and tripping the MIL.

 

Thanks Vader. In all the searching I've done here, I haven't ran across the trouble shooting chart you posted.

Hmmm, MIL=SES light?

I'll let you know what I find out.

Edit: Just took the car for another drive and the problem seems to be gone completely with the temp sensor wire disconnected. It's back to it's old sweet running self in fact.

Now my question is, is there any real reason to replace the temp sensor? I know the sensor is what tells the computer the EGR valve is opening/functioning.

And, no code 32 or SES light.......yet.