I just had a 86 vette engine rebuilt with iron vortec heads, comp cam (fit for a computer),aftermarket base intake and runners, ajustable fuel pressure regulator, and hooker headers. Everything else like the fuel injectors are stock but were cleaned up and tested. Now the problem is that the car wont idle so i cannot set the timing. I took it to a computer secialist which has the car on the back burner and has done nothing but told me he cant get anykind of signal from the computer(computer worked fine before the rebuild). Does anyone know what to do? Please help im vetteless right now Thanks

 

First thing I'd do is check the ECM fuse. In fact, I'd check all of them; might as well since you're already there anyway.

I'd then insert the ignition key, turn it to on and see if the Service Engine Soon light illuminates. If it does, so far so good.

I'd then remove the key, insert a paper clip or jumper wire bent into a 'U' shape and plug it into the A&B terminals of the Assembly Line Diagnoistic Link.

The ALDL is located screwed to the dash pad in the area where your right knee would be with you sitting in the driver's seat. A&B are the top two right openings in the connector.

After doing that, turn the ignition key to "ON" but do not start the engine. The SES should then begin to blink code 12 and the main fan should come on.

Code 12 is one blink, then a short pause, then two quick blinks, then a longer pause, then one blink another short pause and then two quick links. This will repeat one more time for a total of three times.

Code 12 says that the ECM is functioning.

After Coded 12 has blinked three times, any stored error code will be blinked three times. For code 34, for example, the SES will blink three times, then a short pause, then blink four times and a longer pause. This will repeat two more times for a total of three, afterwhich the system will move on to the next stored error code if there is any.

After all the stored error codes are blinked, the system will begin to blink Code 12 again, letting you know that all error codes have been displayed.

Remove the ignition key and then the paper clip.

If none of this works - you don't get any SES blinking, I'd next check the connections to the ECM. The ECM is located behind the dash pad on the passenger side. There are a few screws to drop the cover (the one with the courtesy/footwell light) and with you upside down on your back you'll see two screws that hold the ECM in place. I can't remember exactly, but the screws have either 10mm or 12mm heads.

Remove those two screws and the ECM will slide down.

Your car uses an ECM with the last four numbers of 7165 (it's also sometimes referred to as 165, dropping the 7) and they're plentiful. Many Vettes and "F" body cars (Camaros/Trans Ams) ect, use the same ECM. The only difference is the PROM which is plugged in to the ECM.

Most auto parts stores sell remanufactured ECMs for about $100; that's where I got my replacement ECM a few years ago; O'Reillys auto Parts.

I'd make sure all the connections are tight and recheck using the paper clip/jumper wire.

If still no good, I'd borrow an ECM for a buddy who has the same one (7165) , swap PROMS and try again. If still no good, I'd try his ECM and HIS PROM. If it works with his ECM and PROM, then you'll know that your PROM is the culprit.

If his works in his car but not in yours, then you know it's a wiring problem somewhere. As far as tracking down the wring, you'll need a service manual that has the diagnostic procedures showing which wires to check and how.

To me, this is by far the easiest way to isolate whether the ECM is good or not. The service manuals will have a somewhat more complicated way of checking it though.

Hope this helps; keep us posted.

Jake

 

im going to give it a try and see what comes up ill let you know. thanks again.