bad ecm?
Race Director
Joined: Jun 2004
Posts: 13,961
Likes: 707
From: WI
Mine did, it had some odd quirks though. Mine also had a reman sticker on the computer that I noticed when I got to testing it. It can partly fail in all sorts of ways. I followed the FSM troubleshooting.
Instructor
Joined: Mar 2008
Posts: 148
Likes: 0
From: Rindge NH
It will run with a bad ECM.
When I had a bad ECM it didn't throw a code (jumpered pins on the ALDL). My car idled way high - 2500rpm. Other odd things wouldn't work either - fuel economy calculations, upshift light....
I tried to have the car scanned and the stealership couldn't communicate with the ECM through the reader, leading to the bad ECM diagnosis.
Replaced the ECM, car idled fine, all the dash functions worked. I used a reman unit from one of the chain stores - autozone, advance auto, I dont' remember which. Price wasn't too bad, either. Just need to remove the chip from yours and put it in the new/reman ECM.
Turns out the ECM I replaced was a reman unit - the instruction to write a number from the original ECM on the reman unit wasn't followed by the person who last replaced it, so I don't know whether that number is critical or not.
When I had a bad ECM it didn't throw a code (jumpered pins on the ALDL). My car idled way high - 2500rpm. Other odd things wouldn't work either - fuel economy calculations, upshift light....
I tried to have the car scanned and the stealership couldn't communicate with the ECM through the reader, leading to the bad ECM diagnosis.
Replaced the ECM, car idled fine, all the dash functions worked. I used a reman unit from one of the chain stores - autozone, advance auto, I dont' remember which. Price wasn't too bad, either. Just need to remove the chip from yours and put it in the new/reman ECM.
Turns out the ECM I replaced was a reman unit - the instruction to write a number from the original ECM on the reman unit wasn't followed by the person who last replaced it, so I don't know whether that number is critical or not.
Melting Slicks
Joined: Jan 2008
Posts: 2,065
Likes: 1
From: Jasper Texas
The ecm in my car is a napa reman, and the sticker fell of when I took off the pass. side kick panel, must be a solid 8-10 years old.
Burning Brakes
Joined: Nov 2004
Posts: 897
Likes: 12
From: Land of Whiskey Rebels, PA
My answer is yes, but it would run in "limp" mode, as mine did.
I had some of the same symptoms as you. After replacing the usual suspects (sensors) with no improvement, I took it to a specialist. Turns out a previous owner installed a performance chip on the ECM, and it messed up the computer (so said the technician). He installed a re-man unit, cleared the codes, etc., so she runs like new now.
I can't wait 'til the salt gets washed off the roads so's I can go cruisin', again.
I hope this helps you.
Mike
'90 'vert
I had some of the same symptoms as you. After replacing the usual suspects (sensors) with no improvement, I took it to a specialist. Turns out a previous owner installed a performance chip on the ECM, and it messed up the computer (so said the technician). He installed a re-man unit, cleared the codes, etc., so she runs like new now.
I can't wait 'til the salt gets washed off the roads so's I can go cruisin', again.
I hope this helps you.
Mike
'90 'vert
Race Director
Joined: Jun 2004
Posts: 13,961
Likes: 707
From: WI
A chip won't mess up the ECM, it's possible to install one incorrectly though without using the stock chip in piggy back.
Mine did not run in limp home mode with the bad ECM. It wouldn't enter closed loop mode. I ran through the FSM chart, easy to test the O2 which was my first guess. After that it was grounds and multimeter work.
Mine did not run in limp home mode with the bad ECM. It wouldn't enter closed loop mode. I ran through the FSM chart, easy to test the O2 which was my first guess. After that it was grounds and multimeter work.
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