miss/backfire
Thread Starter
8th Gear
Joined: Sep 2008
Posts: 8
Likes: 0
From: Fort Wayne Indiana
miss/backfire
A while back started having a miss problem with the car, some days it would run great other times it would seem like it was running on 6 or 7 cylinders. This went on for probably a year, but the car isnt driven very often. So this summer I decided to tear into it and try to get it running right, So I started with a cheap set of autozone plug wires just to see if they were the culprit... There were 1 or two bad wires that must have been rubbing or hitting the manifold not sure which so I figured that was the problem. Started the car after the new wires, and it ran the same as it did before, except now under heavy and sometimes light load you can here popping from the exaust, probably backfiring. Ordered a set of summit street/strip 8.5 wires thinking that the cheap wires were just that, cheap, and got some new spark plugs for it. Still have the same problem. Checked spark on a couple of cyclinders and the spark seemed to be weak, so i bought an msd coil hoping that this was the problem, put it in today and still have the same problem. I am starting to get burned out and need some fresh ideas.
Thanks.
Thanks.
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
The ICM could cause some of your symptoms But usually would cause a no run condition. But not to jump the gun, you probably have a bad opti. No codes just poor running and a wide variety of different symptoms. Check all you can first but I think you might end up there.
Thread Starter
8th Gear
Joined: Sep 2008
Posts: 8
Likes: 0
From: Fort Wayne Indiana
That was kinda what I was leaning towards since they are known for them. But with no codes I wasn't so sure plus the opti is not exactly a cheap part to throw at it and hope. But it is an early 92 which had the non vented opti and the car has been auto-crossed for most of its life. The thing that kinda pushed me away from the opti is the fact that it has only 42k on it. Do you think it could just be the cap and rotor wore out? Also if I were to tear apart the car and pull the opti can you normally visually see that the opti is bad?
Intermediate
Joined: Aug 2008
Posts: 36
Likes: 1
I have a 92 lt1 with 53k miles and have exactly same symtoms and did exactly same replacement of parts trying to eliminate simple problems before going after opti....I am waiting for new gm opti to arrive and am fairly confident it will fix problems, after getting advice and reading this forum. Let me know how yours works out.
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
That was kinda what I was leaning towards since they are known for them. But with no codes I wasn't so sure plus the opti is not exactly a cheap part to throw at it and hope. But it is an early 92 which had the non vented opti and the car has been auto-crossed for most of its life. The thing that kinda pushed me away from the opti is the fact that it has only 42k on it. Do you think it could just be the cap and rotor wore out? Also if I were to tear apart the car and pull the opti can you normally visually see that the opti is bad?
When I replaced my opti I disassembled it and did a close inspection. I could see nothing wrong with the cap or rotor. No carbon tracking that I could see and the eight studs had little corrosion for a unit that was in there for over 10 years. I did not see any bearing wobble either. All that looked off color was a bit of rust on the disk with the slots in it. At least to by the eye, the slots looked OK. The new opti did fix the problem.
You still have to do the same work to replace the cap and rotor in the opti. I don’t know what the success rate others have had over the years replacing caps. But after doing all that work if the car has the same problem you still don’t know where you are. Still could be the opti or something else. By replacing the whole opti is more complete way and on the chance its not fixed, you can look to other possibilities and not look behind you. Besides, caps and rotors are not cheep either.
