EGR/ECM trouble?

[Matt Weiser]

I've been jawing about this over in the Scan Tool section, but was hoping maybe you guys could help, too.

My car is a hybrid, an '83 Chevy Malibu wagon with '86 TR drivetrain, wiring harness, ECM etc. I just got it running and everything looks and sounds good, except Tlink shows zero activity by the EGR valve, and what seems a lot of part-throttle spark retard. So I did a diagnosis on the EGR system (following the factory manual) and decided to install a new EGR solenoid. Nothing changed. According to the diagnosis procedure, the only other cause at this point would be a bad ECM. Is this possible? Has this ever happened to anyone before? Could I be missing something obvious? Is it possible the EGR valve is working and it's just not showing up on Tlink? (I think not due to the spark retard I'm getting.) I'm not showing any error codes.

I have an appointment for a smog check tomorrow. Should I go ahead with it and cross my fingers or solve this problem first?

Thx...

 

[Matt Weiser]

Well, this story has a happy ending, but a silly one...

As part of this swap project, I installed a B&M Megashifter in the car. But I delayed hooking up wires from the shifter for the park/neutral switch and backup lights, thinking it was a low priority until I got the car running right.

Well, I started looking at some wiring diagrams and realized the TR's park/neutral switch feeds through the ECM, it's not just a starter lock. So on a hunch I hooked up the park/neutral switch to the shifter, and bang, the EGR started functioning. Apparently, the ECM won't start controlling the EGR, and probably other functions, until it knows the car is in gear.

Anyway, with the wiring done after dark last night, I took the car in for its smog test this morning and it PASSED! Happy ending!!!

Thanks for the help everybody!