I have a friend who has an 86 and is thinking of replacing the computer due to erradic codes. He has done all the checks listed in some threads here on the forum. Does anyone have any specific computer model numbers that may be updated from the original factory unit. Any suggestions or help is appreciated. Happy Holidays to all on the forum. Be Safe.

 

The 86-89 ECMs are the same service #, and there is not an updated unit that is plug & play. While it couldn't hurt to try a spare ECM, I wouldn't go buy a new one for $ unless it's giving legitimate signs that it's a bad ECM; I'd try & borrow a spare, or find a cheap used one that you could resell if it's not the solution.

Without background on those particular codes, I couldn't tell ya anymore.

 

There is a GM TSB for the '86 ECM. The symptoms for the TSB are bad idle and multiple codes. I have the TSB printed up but it's at work.

 

Do you mean a TSB for the ECM or the PROM? I am aware of a TSB for the PROM but not the ECM. I would like to see the TSB if you wouldn't mind posting it or a short summary of its contents.

 

Your correct. It deals with updating the PROM. I am looking for the TSB onling now.

 

http://www.nhtsa.dot.gov/cars/problems/tsb/central2.cfm

See if this link to the TSB works

Link didn't work but here's the beef:

Make: CHEVROLET
Model: CORVETTE
Year: 1986
Service Bulletin Number: 86-162
Bulletin Sequence Number: 152


Summary Description:

ENGINE CALIBRATION CHANGE: TO IMPROVE DRIVEABILITY AND ELI NATE FALSE SERVICE E NGINE SOON LIGHTS-NEW SERVICE CALIBRATORS RELEASED FOR 1986 5.7L TPI ENGINE CALI BRATORS ADDRESS-ROUGH IDLE ON BOTH HOT AND COLD ENGINE-CHUGGLE OR SHUDDER AT L OW SPEEDS-SURGE AT ROAD LOAD-ENGINE OVERSPEED-HESITATION ON ACCELERATION-SERVICE ENGINE SOON LIGHTS-1986 CORVETTE ALL

Here's another:

Make: CHEVROLET
Model: CORVETTE
Year: 1986
Service Bulletin Number: 86-162REIS
Bulletin Sequence Number: 038


Summary Description:

ENGINE CALIBRATION CHANGE: TO IMPROVE DRIVEABILITY AND ELIMINATE FALSE "SERVICE ENGINE SOON"LIGHTS-REISSUED TO PROVIDE A REVISED CALIBRATOR FOR USE ON 1986 CORV ETT. ITH ALIMINUM HEADS AND MANUAL TRANSMISSION-86-162 DESTROYED-NEW SERVICE CA LIBRATORS RELEASED FOR 1986 5.7L TPI ENGINE-CALIBRATORS WILL ADDRESS: "ROUGH IDL E"/"CHUGGLE OR SHUDDER"/ "SURGE"/"ENGINE OVERSPEED"/ "HESITATION"/"SERVICE ENGIN E SOON" LIGHTS-ELIMINATES: IF ENGINE DIAGNOSTICS AND REPAIR NOT CORRECT REPLACE CALIBRATOR IN ECM-ALL 1986 CHEVROLET CORVETTE MODELS


[Modified by tworottiedogs, 6:52 PM 12/26/2002]


[Modified by tworottiedogs, 6:53 PM 12/26/2002]

 

There is an updated ecm for 86-89. It's part # 16198259.

 

Just wanted to add that when I bought a updated prom for my 86,the car ran soooooo much better.Basically GM improved the proms over the years and idle speed is restored under load and improved over the previous settings.
This may not be the fix but it worked for me. :cheers:

 

Thanks all for your replys, I will pass this along to him. Hope all have had a Good Holiday and Have a Safe New Year. Tom