ECM Question
Thread Starter
Melting Slicks
Joined: Jun 2004
Posts: 3,032
Likes: 4
My digital dash shows scrambled data... and it seems to go in and out randomly (yes i've checked all the grounds, and it has been serviced). Also I read one other forum member solved a hard starting problem after he switched out his ECM... I'm thinking maybe that would solve some problems? Any one wanna guess?
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
One time going to work on I275 all of a sudden it felt like I was running on 4 cylinders and the engine ran hot. I called my mechanic and it started after work ok and ran ok when I took it to his house. He drove it the next day and it did it to him and a new ECM fixed it. The other three times I got an error code for a defective MAF and the car ran open loop, bad ECM. The last ECM installed was a different part number from GM and it has held up now for about 10 years.
Drifting
Joined: May 1999
Posts: 1,478
Likes: 3
From: Sacramento, CA Money can't buy happiness - but it's more comfortable to cry in a Corvette than a Yugo.
Attaching a scan tool and not being able to retreive codes is one good indicator of a bad ECM. In a similar vein; using a paper clip to jumper pins A&B on the ALDL and not getting a code 12 is another indicator. Driving with a scan tool attached and scanning and seeing several different codes all set at once for no reason is another indicator.
NAPA selle rebuilt GM ECMs for about $110. I replaced mine with a NAPA unit 5 years ago and have had no problems since. I'd check there or get one from the guys at Superior Chevy Wholesale Office - Parts Department 800-728-8267. They have been supplying the CF members Genuine GM parts at geat prices for quite some time.
GM replaced the original early C4 ECM recommended part #s with an improved one which is why jfb got one with a different part #. The unit you will get if you buy a new ECM from GM or NAPA should be the improved ECM.
NAPA selle rebuilt GM ECMs for about $110. I replaced mine with a NAPA unit 5 years ago and have had no problems since. I'd check there or get one from the guys at Superior Chevy Wholesale Office - Parts Department 800-728-8267. They have been supplying the CF members Genuine GM parts at geat prices for quite some time.
Originally Posted by jfb
The last ECM installed was a different part number from GM and it has held up now for about 10 years.
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Racer
Joined: Feb 2003
Posts: 437
Likes: 2
From: Georgetown Maine
Mid America has ECMs for $99 getting mine overnighted because we are heading for Gettysburg/Carlisle the 21st so I'm running out of time. This forums store has them for $95 except they are backordered 
I've got some idle/start problems except of course when it goes to the garage 
I've got some idle/start problems except of course when it goes to the garage
Thread Starter
Melting Slicks
Joined: Jun 2004
Posts: 3,032
Likes: 4
Thanks for the help guys- I'll check the local auto stores tommorrow... I'm wondering, anyone else out there have ECM stories? Any different things happen to poeple when they go bad? I'm gonna check if mine is giving the right codes tommorrow too
Team Owner
Joined: Sep 2003
Posts: 20,172
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From: Freedom is never more than one generation away from extinction.
St. Jude '03 thru '24
Does the replacement ECM come with the "chip"? Or do you bank on the rebuilder loading the correct .bin for the P/N?
-JRC-
-JRC-
Thread Starter
Melting Slicks
Joined: Jun 2004
Posts: 3,032
Likes: 4
Originally Posted by JrRifleCoach
Does the replacement ECM come with the "chip"? Or do you bank on the rebuilder loading the correct .bin for the P/N?
-JRC-
-JRC-
Race Director
Joined: Apr 2004
Posts: 17,066
Likes: 3
From: Milpitas ca
Originally Posted by mikey whipreck
Isn't the "chip" the removeable PROM that's attached to the ECM? Or am I getting parts confused?
When you see it there will be a "lever" on each side. Just push those to the side and pull chip out.
Team Owner
Joined: Sep 2003
Posts: 20,172
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From: Freedom is never more than one generation away from extinction.
St. Jude '03 thru '24
Originally Posted by jabez
The chip easily pops out of the ECM.
When you see it there will be a "lever" on each side. Just push those to the side and pull chip out.
When you see it there will be a "lever" on each side. Just push those to the side and pull chip out.
I'll try to make my point another way. Whenever I install a rebuilt carb, I'll replace all the fuel and air jets from the original carb into the replacement unit. This way the factory "tune" will stay with the engine. This has always worked very well for me.
But when replacing an ECM should the same practice be carried out or "trust" the rebuilder to have programmed the prom correctly?
-JRC-
Race Director
Joined: Apr 2004
Posts: 17,066
Likes: 3
From: Milpitas ca
Originally Posted by JrRifleCoach
jabez and mikey,
I'll try to make my point another way. Whenever I install a rebuilt carb, I'll replace all the fuel and air jets from the original carb into the replacement unit. This way the factory "tune" will stay with the engine. This has always worked very well for me.
But when replacing an ECM should the same practice be carried out or "trust" the rebuilder to have programmed the prom correctly?
-JRC-
I'll try to make my point another way. Whenever I install a rebuilt carb, I'll replace all the fuel and air jets from the original carb into the replacement unit. This way the factory "tune" will stay with the engine. This has always worked very well for me.
But when replacing an ECM should the same practice be carried out or "trust" the rebuilder to have programmed the prom correctly?
-JRC-My car is stock so I had no reason to replace the chip.
Melting Slicks
Joined: Apr 2003
Posts: 2,150
Likes: 6
From: NS
Originally Posted by mikey whipreck
My digital dash shows scrambled data... and it seems to go in and out randomly (yes i've checked all the grounds, and it has been serviced). Also I read one other forum member solved a hard starting problem after he switched out his ECM... I'm thinking maybe that would solve some problems? Any one wanna guess?
Thread Starter
Melting Slicks
Joined: Jun 2004
Posts: 3,032
Likes: 4
Originally Posted by Atok
I'm not sure about your year Vette, but the dash in my '95 is controlled by the CCM, not the ECM. My CCM was replaced after the display went a little wonky.