Mooney78865

I have a 91 coupe and have been fighting a code 32 for a bit now. I have finally run it down to the egr solenoid always being "grounded". I have been testing the system with a mighty vac and have good vacuum every where it should and would "ground" the solenoid during testing to confirm operation.
After beating myself up with a lot of "I've fixed it now" I re installed the vacuum gauge and low and behold the egr solenoid would open as soon as the engine started. (it was not grounded with ignition on and engine off)
The car is new to me with what looks like a re manufactured ECM. Could the ECM have failed?

DanielRicany

Possibly, but I would look at a wiring diagram before you replace anything. The ECM should ground the solenoid, but it will depend on a couple conditions. You need a wiring diagram or a description and operation from All Data to figure it out.

Benny42

Speed density cars are very sensitive to free flowing exhaust and code 32. We need
more info to tell you very much. Is your car modded? Code 32 typically sets when EGR
is requested by the ECM but not sensed by the MAP sensor.

Mooney78865

The car is stock. Everything I've read says that the egr solenoid is "grounded" when conditions are met for EGR operation. Which makes me wonder why it is grounding as soon as the engine starts. Engine hot or cold it grounds.

Benny42

The EGR solenoid is closed when grounded. It opens when the ECM requests EGR and
ungrounds the solenoid. It seems backwards, but thats how they do it. Code 32 is a NO
EGR code. Have you tested the EGR valve, the diaphragms do fail.

tbirdsps

I can't wait to find out. Mine does the same thing. Everything checks out but the valve can't be bench tested. Not sure how to test. If I force it open the engine does stall but what rpm is required to actually confirm it's opening?

Mooney78865

Everything I read is that the 91 is a normaly closed solenoid. I take that to mean that until there is a ground applied the solenoid remains closed. The ground is applied when conditions are met opening the solenoid.
As to all the other questions, yes, I've tested/replaced all of the Auto Zone parts with Delco or Delphi.
So now the question is, does the ground come on at start up and is removed when conditions are correct? I hope so as that would solve everything.

Cliff Harris

You could try blowing or sucking through the solenoid when it's unplugged.

Then do the same with 12 volts applied to it. I think it gets turned on when the A & B contacts on the ALDL connector are connected together. One way to tell is to short A & B and then plug and unplug the connector on the solenoid. It will click if it's powered.

According to my '86 ECM programming, EGR gets commanded under these conditions:

TPS > 1.95% (EGR currently commanded)
TPS > 3.13% (EGR not commanded)
MAT > 0.5°F
Coolant temperature > 56°C = 133°F