A little background first, but if you don't need it please shoot down to the end where I get down to my main question about a possible misfire and possible starter dying.

I bought this camaro earlier this summer, and even though it only had 83k miles on it, it needed attention, having it barely been driven in the last 10 years probably didn't help some items.

Anywho, thanks to this site I sorted some of them out. I replaced the ac compressor/condensor/air dryer/ac expantion valve, now the a/c works EXCEPT when the a/c is turned on it makes a clunk, but works fine after that.....

The car started and ran pretty rough so I replaced the fuel pressure regulator, plugs, wires, and cleaned out the egr (had a check engine light for that). While I was ordering parts I figure since it was cheap I would also replace the iac valve to see if it helped with the rough idle, and it did not.

It used to have a little longer cranking time to start when cold, but not too bad, but had a much worse time cranking when a warm restart and a strong fuel smell. I hooked up a fuel pressure gauge and noted it shoots up to 42psi, then looses about 20 psi after half a minute without the car running. After replacing the fuel pressure regulator, the warm restart problems are gone, and seems my cold start is due to what I am guessing the check valve bleeding off pressure when not running. I have 36psi when the motor is idling, and it shoots up to 42 when accelerating, so seems the fuel pump is fine and I am not pulling it just to replace the check valve, I'll just cycle on and off the accessories twice when its a cold start and that seems to have been just fine.

The starter has always been noisy (not sure how long my uncle drove the car with the longer cranking to get it started, but guess it helped shorten the life of it), and now it starts to crank for half a second, hesitates, then starts the car but seems to spin slower than it should when cranking. So I am guessing either the starter is finally giving up the ghost, battery is getting weak, or alternator is not keeping up. I will have the battery tested this weekend, I asked my uncle (original owner) if the battery is older than 5 years, he is not sure, but said possibly, nothing on the battery says a date of sale or manufacture that I can see. I used the scan program to see what voltage the ecm is seeing and it fluctuates between 12.9 and 13.6 when idling and warmed up, so think the alternator is fine. Do the starters on the 3.4 need to be shimmed, if so, where do I find the speck for the gap?

ALSO, and to my main reason for posting and asking for help is the repairs so far has helped with the idle and overall running of the car, BUT there is still a rough idle. It is not as bad as it used to be, but still not what is should be, and when listening to the tailpipe it seems like a random pop every couple of seconds or so, and again guessing that is a misfire. I know gm had intake gasket issues in the mid 90's and sprayed water around the intake, but did not notice a change in idle. There is no check engine light, so I am leaning towards maybe a coil pack going bad, but can't seem to find any info on if there is a way to test these as I don't want to parts cannon the car any more than necessary. Anyone know of a way to test them? Any other ideas to help troubleshoot the rough idle? I have been repairing my cars since I started driving 25 years ago, but I am not a tech and my troubleshooting skills have much to be desired, so any help is appreciated.

 

to much fuel can cause backfire. fuel builds up in the exhaust and ignites every so often.