Could the ECM be going bad?
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Le Mans Master
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From: Fort Worth Texas
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Could the ECM be going bad?
Tonight I opened up my '727 ECM (under hood version) and put a different chip in. I start the car and it's idling rough, like three plug wires are off. Won't rev up. I plug in Diacom, no codes..... injector pulse width at idle is way high, about 4ms. Should be 1.9-2.0ms at idle. IAC is working, everything else looks fine. I turn the car off, put a stock chip in, still the same. I push the large connectors from the harness in to make sure they are connecting good, and push the memcal in real good. The car starts up and idles perfect. Diacom shows 1.9 pulse width at idle. Runs like a champ now. Kinda strange, got me worried for a minute.... I'm wondering if the ECM is messing up? I just sold my spare ECM thinking I would never need it! Guess I might pick one up again just for safe keeping!
Melting Slicks
Joined: Apr 2001
Posts: 2,105
Likes: 220
From: Ca.
Re: Could the ECM be going bad? (Marcho Polo)
Sounds more like just a bad connection-I've had one or two wires at the ecm and at the dash give me problems. All kinds of strange things that drove me crazy. The little metal connectors on the ends of the wires have a tab that sticks out and is supposed to catch on the plastic harness end-it bent in enough to back out and cause the intermittant poor connection. Yes the piece that snaps over the harness end should keep all the wires from backing out at all-but it sure doesn't on mine! All's I had to do is gently bend the tab out more and then put it back in untill it snapped firmly.
Melting Slicks
Joined: Aug 2001
Posts: 2,516
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From: Lockport NY
Re: Could the ECM be going bad? (Marcho Polo)
I just sold my spare ECM thinking I would never need it!
...I'm a pessimist; I plan on catastrophy...When it happens, I'm ready... :D
I'd agree with the loose connector theory...Possibly check your pin contacts for patina...My boneyard ECM was pretty bad...Grayish oxidation/patina on every pin...A soft brass toothbrush (gun cleaning brush) got rid of it...
Thread Starter
Le Mans Master
Joined: Mar 1999
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From: Fort Worth Texas
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Re: Could the ECM be going bad? (Mojo)
Craig,
Are you using a modified memcal? I ask because I've been having a problem with some of my pins desoldering on my ZIF socket.
Are you using a modified memcal? I ask because I've been having a problem with some of my pins desoldering on my ZIF socket.
nah, just a stock memcal that I erase by jamming the switch on my Datarase.... I lay the memcal over the uv light, and put it in a box, then turn it on and close the lid. The eprom is still soldered on there.
Thread Starter
Le Mans Master
Joined: Mar 1999
Posts: 9,663
Likes: 1,680
From: Fort Worth Texas
2024 Corvette of the Year Finalist - Unmodified
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Former Moderator
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Re: Could the ECM be going bad? (Mojo)
You do know that the UV eproms will degrade over time...
Yeah, but you should be able to cycle them hundreds of times before they degrade, right?
Melting Slicks
Joined: Aug 2001
Posts: 2,516
Likes: 0
From: Lockport NY
Re: Could the ECM be going bad? (Marcho Polo)
I just read a post here somewhere that the more you erase one, the longer it takes...10 hours was the time mentioned (I believe)...Don't recall how many burns...
It only took 10 minutes for my "new" EPROM to erase...But that was burn # 1...
It only took 10 minutes for my "new" EPROM to erase...But that was burn # 1...
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Re: Could the ECM be going bad? (Marcho Polo)
Sounds like a problem I had, turned out to be one of the spring loaded connections on the Digikey ZIF sockets wasn't closing all the way... might be due to multiple opening and closing... unfortunately for me the modified chip made by a fellow CF member never would work but the stock chip is just fine and still in and running.. He tried twice programming this chip but it wouldn't work either time.. Has anyone ever had a chip programmed that just wouldn't work???