Hello All,

My car is a 1985 Camaro IROC with a 383, '90 ECM & wiring harness and HSR.

Since I got the motor finished about 2.5 years ago, it's always ran a little rough for my tastes. After doing some additional work, I finally have it running the way I want, once the car is warmed up.

Before it's warmed up, though, it runs awful. No power, sort of chugging, jumping RPM's, etc. After about 10-15 minutes, it smooths out and runs fine.

I have data logged a few times, sent the information to the company that I got my chip from and received new files to burn into my chip. After three times, they said everything was good and there was nothing else they could do/change.

Today, I drove the car for the first time in about 3 weeks. It was running rougher than normal, at one point I pulled up to a traffic light. As I was coming to a stop, I heard a soft "pop", a delay of about 5 seconds and another "pop." These weren't loud like gun shots, almost like someone blowing up a paper bag and then popping it. I was a bit concerned, but I drove the car another 45 minutes without issue.

My questions are: 1) What else can I/should I look at to improve the cold running, if I even can? It's not the end of the world if I have let the car warm up a bit before driving but if I can diagnose and fix what the problem is I'd like to do that and 2) is the backfire anything to be concerned about? Could the car sitting for 3 weeks be the culprit? The car frequently sits for 1-2 weeks at a time, but this is the first time I heard a backfire.

 

Can't offer you much help but my tpi backfires through the intake if I don't let it warm up and rev it but mines all stock with stock tune, I've chalked it up to timing

 

Yeah I would say the timing for sure. I would go through the entire timing process a hundred times until I found a setup that worked. This is one reason why I swapped my TPI 305 for an LT1. I kept messing with the timing, but just couldn't get it just right.

I would do a search for everything that effects timing, go through those systems and tweak and configure every element until you're satisfied. I've had a bad distributor cause weak idle and I'm sure it could cause worse issues. I would check that first.

 

I'm 95% certain it was backfiring through the exhaust - when it happened the first time, I turned around to see where the noise came from. The second one sounded like it was behind me as well. I guess I don't know 100% for sure, but pretty close.

 

Could still be timing or un burnt fuel entering the exhaust in which case you'll have to pull the plugs and see which plug/ cylinder isn't igniting.