I've done all relevant searching I can think of and haven't found anything, so here it goes.

I took my prelude to get an emissions test done on it so I could get a tag. I failed on NO and I figured out the EGR valve wasn't working. One new EGR valve, a used computer, and several runs through the factory service manual for the car and I've come the conclusion that the computer is not supplying ground to the EGR vacuum solenoid to cause the valve to lift.

I've checked the wires to make sure they are good with no breaks in them on the entire circuit. As a matter of fact, when you ground out the circuit at the harness plugs at the ecu the engine stalls because the valve opens. The troubleshooting flowchart has ruled out the valve and control box on the firewall. The only thing it can be is the ECU is not grounding the circuit like its supposed to.

But the thing is this is my second ecu and its doing the same damn thing. Can anyone think of anything I can me missing? Does the vehicle have to be at speed before the computer grounds the circuit? Did this generation of Prelude have problems with their computers?

 

You might want to take your question to this forum:

http://www.preludepower.com

This site is more 3rd Gen(88-91) specific.

Sean

 

Yeah I did, no one can figure it out. Trying to get a broader base of knowledge.

 

go back to Preludeposer.com and PM either BobNova or Motoxxman...they should help out.

It is possible that you have 2 bad ECUs...but very unlikely. More likely is a bad ground circuit at the EGR plug...try using your multimeter and checking for continuity. Then try checking for the corrct voltage on the ECU side of the harness.

Cheers!