I have an 88 IROC and the problems that first began or too lengthy and may become confusing. I currently need some help with a timing issue. I had to put a new/reman distributor in my car. It's my understanding that the timing for the 88 IROC with the TPI is 0 degrees. I have hooked the timing light to it and disconnected what I believe to be the ESC wire (tan with black stripe on the passenger side at the firewall). When I set the timing with the wire disconnected the car runs pretty good. When I shut it off, plug the wire back in the car runs horrible and will hardly stay idling unless I rev the engine. The car has a lot of miles on it but has always ran fine. This happened only after I replaced the distributor. I'd really appreciate some help on this. Thanks, Ryan

Bump the base timing to about 6* and see if that helps.

best of luck!

I had the timing at zero and then retarded it 6 degrees and it starts and runs a little smoother. I advanced it 6 degrees and it would hardly run so I went back to retarding it 6 degrees and see what that does. Is the base timing for an 88 IROC TPI 0 or 6 degrees before top dead center?

The base timing for all TPI's is 6* BTDC. Sorry, but I don't have any ideas to help you at the moment.

Another thing to note how are you setting the timing? TPI motors have there own procedure on how to set the timing not so simple like an old carbed car. You see the problem spark timing is controlled by the ECM and the only way the ECM can adjust the timing to a specific value is if it knows where the distributor is set as a starting point so the distributor is set 6 degrees BTDC without and advance or retarding from the ECM. Like this the comp knows that the distributors base timing is 6 degrees and the ECM can adjust the timing from there as needed. If the timing just simply set at 6 degrees BTDC while the motors running without following the correct procedure the base timing will be not set correctly but the comp will still assume it is as it doesnt know better and will adjust the timing as it always would. This means if the ECM was trying to adjust the timing to 10 degrees BTDC and normally it would only have to add 4 degrees advance but the base timing is actually set at 12 degrees BTDC it will still add the 4 degrees it will just be totally wrong. The result of this is the timing will be wrong across the rev range causeing it to run poorly and have a variety of symptoms depending on what the base time is actually set to.

Are you running a stock chip (6*) or a custom, if custom chip, the timing needs set to what the chip is set at.

Also has the Damper timing mark/pointer been verified.

This can be off due to incorrect parts or damper slipping, key and mark should be in line, tdc.