ECM - How to tell if it’s the problem?

[Montana]

Yesterday an elderly friend of mine who’s a retired SAE mechanic hooked up his scanner to my 89 Corvette to see if there was anything out of the ordinary going on with it. He couldn’t get the ECM to communicate with his OBD I scanner. After numerous failed attempts he felt I may have a bad ECM. Also, after I left yesterday he hooked up his scanner to an 88 Chevrolet vehicle of his neighbors & it communicated with out issue.

I got my 89 corvette back running around the 1st of July but have been plagued with drivability issues & on & off performance issues. Last week I installed a new prom from Jim at TPIS & afterwards it felt really gutless. Wouldn’t spin tires as an example. So could I really have a bad ECU? The current one in my corvette is already an AC Delco reman unit, so it wouldn’t surprise me if it failed again. Along these lines someone else said there is usually a cause so be sure to find it?

 

[Montana]

My current ECM is a rebuilt unit by AC Delco. That was put in before I bought it in 2001. “Made in the USA” dang this is an old remanded unit, even factory approved!

 

[T-Test]

Use jumper wire at aldl connector. Read codes by flashing cil.

 

[Montana]

T-Test, yes I’ve done that before a few weeks ago & have no engine related codes. All my FX3 codes went off because I have all the heads off the shocks & that was expected. I’m not just after codes but now trying to determine if my ecm is on its way out (again). The bad ECZm could be the reason I’ve had unstable performance & why it lost power with the new prom.

 

[T-Test]

Good luck. I spent thousands of dollars to finally get one that worked for my 1995 Dodge Ram 1500 4X4.
All remanufacturing Co.s will lie to your face to take your money.
Don't believe them about their warenties.

 

[Thunderbolt]

If the scanner can not connect to the ECU it could be a 12V power or ground issue in the OBD connector/harness.

 

[Grumpy]

If the ECU is not providing you with the info you require, a multi meter , reading spark plugs ,use of a infra red heat gauge,
and other methods can and should provide you with a secondary route to engine tuning info.
Ill post several links that should be helpful.
if you had a c4 corvette this might also help

tracking down the problem getting the engine started​

If your car won,t start consistently, you need to isolate the problem to the source, you can,t isolate the cause without understanding the process, so you may as well start looking into how and why each step in the process starts , and how each step functions and triggers the next step. your...
garage.grumpysperformance.com

1988 C4 Instrument Cluster Has Stopped Working​

have a 1988 C4 that I had to replace the wiring harness and before installing. I made sure all joints were soldered and all wires were good. When finished installing I did not have my instrument cluster. I do have all the idiot light, blinkers, high beams. They bright and dim as they are...
garage.grumpysperformance.com

Relay/s, Voltage Drop/s, Current Flow, Grounds and ... more​

A relay is nothing more than a device that uses a low-current signal to operate a high-current circuit, he solenoid on your starter is a type of relay that uses the low-current signal from your starter switch to operate the high-current circuit between the battery and the starter motor...
garage.grumpysperformance.com

c4 & c5 corvette trouble codes​

if your corvette won,t start or run, don,t panic its usually easy to locate the problems source, buy a CHEVY SHOP MANUAL FOR YOUR YEAR CORVETTE! RULE#1 never assume a damn thing ISOLATE ,TEST AND VERIFY http://www.professionalequipment.com/ex ... ermometer/ Wide temperature range from -58 to...
garage.grumpysperformance.com

cooling off that c4 corvette​

your stock corvette http://garage.grumpysperformance.com/index.php?threads/thoughts-on-cooling.149/page-3#post-107697 has a rather marginal cooling system if your engines been modified for significantly higher hp levels, that cooling system can be significantly improved upon.I run into this...
garage.grumpysperformance.com

https://www.autozone.com/diy/repair...ring-diagrams-repair-guide-p-0900c1528008fd94

CHECK ALL YOUR FUSES WITH A MULTI METER

c4 & c5 corvette trouble codes

if your corvette won,t start or run, don,t panic its usually easy to locate the problems source, buy a CHEVY SHOP MANUAL FOR YOUR YEAR CORVETTE! RULE#1 never assume a damn thing ISOLATE ,TEST AND VERIFY...

garage.grumpysperformance.com

curing that problem with how your c4 corvette runs badly or won't start

A recurring theme has been replayed over and over, READ THE LINKED INFO CAREFULLY THERES NOT A DAMN THING YOU CAN'T FIND AND FIX WITH A FEW TOOLS, AND SOME FAMILIARITY WITH THE CORVETTE< A SHOP MANUAL IS A HUGE HELP Id strongly suggest you systematically verify the cause rather than making...

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Tales Of The Spark Plug. Engine Tuning By Reading Spark Plugs

I Want Some Suggestions On Potential Problem Sources 1987 Corvette

I've got a 1987 corvette here, in the shop,that had a blown head gasket I repaired, the engines got good compression, and it runs decently when first started and will do so unless its engine is turned off, this is intermittent problem, making it a bit harder to isolate, the engine does not cut...

garage.grumpysperformance.com

upgrading your TPI MAF and CPU links

there's a good deal of info in the links and sub links, you'll really need THAT DETAILED info, the LINKS AND SUB LINKS , AND those SUB -SUB LINKS and the info they contain, so don't skip over reading them carefully. you'll find many guys claiming that aftermarket CPU chip upgrades help...

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