I have a 95 Formula with the LT1. It has started to run extremely rough. It is having a tough time starting up and when it does run it struggles with acceleration and has a frequent backfire while cruising. From what I have gathered it sounds like it could have a cylinder or two not firing which is causing it to backfire. I changed the plugs hoping it was the problem and it had no affect. Engine has always ran a little rich before getting fully warmed up. The plug wires are less than a year old so I doubt they are the problem. The computer is throwing no codes so no help from there. My mech didn't have the proper equipment to diagnose and suggested possibly going to a dealer who has the right equipment but I will not pay the fees a dealer charges. Any help would be greatly appreciated.

Thanks again,
Jesse


P.S. I changed the opti about 3000mi back. Could this be the problem again??

 

Any ideas? In need of some serious help...

 

. sounds like a tough problem. I had this happen to my camaro i know that you replaced the wires less than a year ago. I dont know the cylinder # but check the very back cylinder on the drivers side my exhaust manifold burnt mine in half. Its a possibilitythat it happend to you. It happend to me

 

New plug wires doesn't = good condition plugs now. One could have been burnt as mentioned above.

 

i had a similar problem and it was my fuel pressure reg.

 

Update: There was one badly blackened plug that could have been burnt up. The car has all new plugs as mentioned above but it did not improve the running condition. I can check the wires to see if any are visibly damaged.


If anyone else has anymore ideas please share!


Thanks

 

Bad coil possibly ?? Just throwin out a guess.

 

I guess burnt plug wire like the rest. Get a fuel pressure check done and go from there.

 

Maybe test the EGR per shbox's method.

 

Do the basics on this car, clean the MAF and the IAC valve first to rule them out. I would check in the dark to see if you can see any arcing from the wires. A bad coil can cause this also, they are about $20 new at the parts store and an easy swap. Also check your O2's and ignition module which is attached to the coil bracket. You could also have a bad MAP sensor. More than likely the answer is somewhere in there with the basics. I would suggest Shoebox's page for LT1 help:


http://shbox.com/1/4th_gen_tech1.html

 

It may sound dumb, but did you check the wires because it is tuff to get the wires on the opti all the way on with out taking the balancer off and I kept thinking that I had them on and I couldn't track down a miss. I finally pulled the balancer and double checked and I had one wire that was not fully engaged. Also, had bought MSD wires and I had one wire that had a crack on it right out of the box and another never got a crimp from the factory so.....you may want to check them even though they are newer. Did you check you injectors? If only one is fouling out then I bought it is a reg. or something like that.

 

scott9050 - Great link, thanks.

Steve