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Username Post: Options for ECM for TBI 327        (Topic#369137)
jktucker92 
Silver Supporting Member
Posts: 535
jktucker92
Loc: West Richland, WA
Reg: 02-05-17
08-04-22 07:09 PM - Post#2845471    

My brother has a '63 Chevy C10 with a 327 that I modified to use a TBI setup from a '91 Suburban about 7 years ago. Was running fine up until last year when it started going into limp home mode occasionally (fast blinking CEL). The ECM has a custom PROM that I burned, so I burned 2 spares, and bought another ECM from the junkyard. Swapped out PROMs, and ECM's and it's just getting worse. At first, it would only happen occasionally, now it's happening every other day. In most cases, disconnecting the battery and reconnecting it will fix the issue.
So, while I think this is probably some grounding issue, we can't seem to find any issues, and my brother just wants his truck to run well again. Any suggestions on a replacement ECM to run the TBI setup? Any suggestions how to identify the issue? Both grounds on the engine are good, and there's a good ground from the back of the block to the frame and to the body.



 




Tony1963 
Frequent Contributor
Posts: 1552

Loc: Orlando Florida
Reg: 07-09-18
08-07-22 05:08 PM - Post#2845587    
    In response to jktucker92

I am going to post the obvious here, but I will be clear in that I have never done any type of modification that you have.

The flow of that old 327 engine is going to be a lot different than the 350 engine that it came out of, or even 305.



People fear change because it threatens what they know, or what they claim to know.


 
65_Impala 
Very Senior Member
Posts: 4920

Reg: 12-29-02
08-08-22 07:23 AM - Post#2845604    
    In response to jktucker92

Well, GM stuff is very reliable. You'd have to change the wiring harness and ECM together.

Very little puts the ECM into the fast flashing light mode, usually it means the EPROM is bad. Is the speed maybe too slow or could they be cheap knock-offs?



 
jktucker92 
Silver Supporting Member
Posts: 535
jktucker92
Loc: West Richland, WA
Reg: 02-05-17
08-08-22 08:12 AM - Post#2845608    
    In response to 65_Impala

Thanks for the response. I did tune the PROM chips for the 327, and the truck was running really well before this issue started. Thanks for the input on the PROM chips. The PROM chips came out of the ECM's I installed, so while they're very old, they should have the right specs. I just erased and re-programmed them. It's possible that I just have two bad ECM's. I just swapped in a 3rd ECM to see if the problems change. Unfortunately, it's a 1228747 ECM, and the PROM chip hasn't been tuned. It came out of a 350, so it will run a little rich, but if the problem goes away, we can assume that the problem is either the ECM or PROM chip.
As for any other advice, while the GM ECM's are very reliable, it is 35 year old technology. If we were to go another route for the ECM, what are people using out there? What is their experience with the new system? There seem to be a lot of aftermarket systems out there, but none of them are cheap.



 
65_Impala 
Very Senior Member
Posts: 4920

Reg: 12-29-02
08-08-22 11:05 AM - Post#2845619    
    In response to jktucker92

I don't know of any aftermarket ECM replacements that would make sense. Higher end Holley ECMs could likely work but that's an expensive way to go just to replace the GM unit. The likes of a Holley Sniper would be the most suitable, but I really can't say it'd be more reliable. Harder to get fixed and running again most likely if it does fail since it's all contained in the TBI unit.

A Megasquirt could be used with a little bit of work.



 




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