OK, this is the strangest thing I have seen. I searched everything for a PM6, and didn't find anything that addressed this issue.

Here's the issue.. I have 3 (had 4) PM6s. 2 of the 3 are 91 ECUs, one I have chipped and put the stock ROM back in for testing this issue, the other one is stock, the 3rd one is an 88 PM6. (That 4th one was a90 that did the same things as the 91s but I thought it was the ECU and junked it. )

When I have the 88 ECU in, I start my car, I turn it off, remove the key, everything is fine. When *ALL* of the 91 ECUs are used, I start my car, it runs pefect, turn it off, remove the key AND IT'S STILL RUNNING!! I have to pull the A plug on the ECU to get it stop the engine.

First thought, of course, is ignition switch, nope. It works fine with the 88 ECU. Second thought I chipped my ECU incorrectly, or dripped solder or osmething stupid. I thought that myself, that's why I got another ECU that was untouched, same issue. I replaced my main relay thinking there was something wacky in it, same issue...

What the heck is going on?!!?

Background on my car: It's a 91 DX, with the MPFI swap that works with the 88 PM6.. No other electrical mods done.

 

 

uhhh turbo timer maybe?

 

if you need to unplug A plug to kill your motor, did you try any of the other 2? If not I'd try because if you did and the A plug is the only one killing your motor, I'd trace each wire of the A plug if its somehow connected/related to keeping your motor running. Its a start...no pun intended, hehe

 

i think the term for what your car is doing is "dieseling". A girl I know with a Saab had that same problem. I think maybe your main relay (PGM/FI) is stuck on or something. Try replacing it.

 

Ya.. I can pull any of the plugs, and it'll shut down. I just pull A because it's bigger and easier to get ahold of.

As for the main relay, I've already done that.. :-/

 

batery kill switch, cures all and resets ecu!!!!!! !!!!!!!

 

I have a battery kill switch. Most like to refer to it as an ignition switch.

Hrm, no ideas anyone?

 

Are there any pinout differences between the two ECUs? I honestly can't remember off hand, and I'm stuck at work with no time to check, but that is the first place I'd look.

Also, if there are any dead pins or unused sensors that an 88 doesn't have that a 91 does have. I'd check those.

I don't know much about 88's.


Does it run fine, or does it stumble around once you cut the key off?


[Modified by therealciviczc, 4:02 PM 2/26/2003]

 

alright, I've never had a problem like this before but heres a few ideas you may want to check.
- First, check for any vacuum leaks, check the mounting bolts at the throttle body and intake manifold, make sure all the vacuum lines are connected and in good condition(spray some carb cleaner on the hoses, if the RPM's go up when you spray a certain hose, that hose has a leak.)
- Is the car overheating or anything??
- what about timing, do u have it advanced at all?
- another thing i've heard to check is the "thermo-controlled air cleaner heat valve" this could be stuck open

 

All of these things make sense...

Except, when you factor in that I plug the 88 PM6 into the car, it runs fine. Ignition works normally.

Thanks for the help, but I'm thinking it's electrical. Maybe the ECU gives power to something a little differently than the 88.. I'm not sure. But a mechanical problem doens't really work in this instance.

 

That's why I'm thinking it has to do with whatever difference existed between the two years. There has to be something that an 88 ECU ignores that a 91 doesn't. That's where I'd start looking for electrical problems.

 

yes, it HAS TO BE electrical. get a pinout listing for both ecu's and compare them side by side. there has to be an incompatibilty somewhere that was missed.

 

WEIRD!!!! Man I wish I could help, but you've got me stumped, I can't think of anything to explain that.
Have you seen this guy around?


I think he has something to do with it...


[Modified by illdezignzls, 2:32 PM 2/26/2003]

 

My car just started to do that the other day too! But get this only when your foot is on the brake? Also when you start the car the taillights go on.. And when you don't even have the car started or anything you put your foot on the brakes and all the acc. lights on the dash go on and the stereo or whatevers on does too. WTF? Did you find out anything about yours or what. My car is totally stock except intake and exahaust and stuff. It happens all at once too, weird huh? The car runs perfect still. Anyhelp thanks.

 

Your problem sounds like a ground or a wire being pinched. Its been so long since I've played around with the fuse box, but if you search it, I think you'll find a bad ground, missing ground, poor ground, or something.

 

When you turn the key off, CHECK THE IGNItion switch. Pop the console out
there are 2 + screws in the back take them out. Look at it. Take it apart from the key lock. The way i drive my beater car is. I use the key and turn the ignition switch on. Then hide the switch. Then put the key in the lock. They can't steal my car no matter what because the steering is lock. but my car stays on until i turn it off with the key.

 

I also have a 91 DX hatch that has the MPFI swap done to it with a 91 Si ECU. But my car only keeps running if It's in reverse! So I' think when it gets warmer out I'm going to check every freakin ground on the car, should be easy, considering I'm totally stripping the car and rebuilding it.