z28onTweenkies

I can't seem to find the answer to my question in the archives so here goes. I have my plenum taken off on my 87 and I can only back out one of the two bolts on my egr valve due to some funky sensor on my egr valve being right above the bolt. Does anyone know how to get around this sensor? What is it exactly? This is a totally stock, GM original 168k+ mile valve.
I get the SES light after driving 10 minutes or so around town. I get two codes, first I get the EGR (32) code and second I get the VSS (??) code because my speedometer doesn't work. Does it mean anything since I get the light after such a short drive? Maybe I have a problem with the solenoid? Thanks in advance

Kevin91Z

iTrader: (1)

The sensor on the EGR valve is the EGR temp sensor. Its job is to make sure the EGR is working when the computer tells it to open, on 85-89 TPI cars. You should be able to remove the EGR sensor with an open end wrench on that bolt. If the EGR valve is dirty with carbon, or the solenoid isnt working, or the temp sensor isnt working, it will set the SES light for code 32, as you saw. It normally doesnt come on unless you're driving on the highway. The light you're seeing right away is for the speedo not working. That needs to be fixed right away as the car is probably running rich and using extra gasoline.

rgarcia63

There are EGR temperature sensors, this is not one, but does use heat to operate, and does the same thing as an EGR temp sensor, or EGR vacuum switch.
The sensor is an "EGR Diagnostic Switch," and it works like an old toaster pop-up mechanism, it has a curved strip of bi-metal inside that expands as it's heated, and it's calibrated to complete a connection to ground at a preset temperature informing the ECM that the EGR valve has opened.
The switch should be open when cold, and closed when the hot exhaust gases heat it up.

Since the DTC isn't set until the car has been driven for ten minutes then the switch is not closing.
If you suspected that the EGR valve and solenoid are working properly then try the following:
Bypass it by disconnecting the sensor, connect a toggle switch (in the open/off position) to the ECM EGR diagnostic wire in series to ground, start the engine, flip the toggle switch "ON" and the SES light will come on sooner if not immediately.
Turn off the engine to clear the code, reset the toggle switch to "OFF", then warm up the engine, hold the rpm at 2.5k, the ECM should be commanding the EGR valve to open, flip the toggle switch, the ECM will sense the decrease in the EGR Diagnostic signal voltage and believe that the EGR valve has indeed opened, then flip the toggle switch "ON" and the SES light should come on again.