my 96 firebird....sputtering and misfire?

my firebird has been having some issues lately. i would drive fine until i get to 30 miles an hour than it sputters and you hear a slight misfire. I had thought of either a clogged fuel filter or, the worst: catalitic converter!

my mechanic said the filter was clogged, he changed it. it still did the same thing. he unplugged the HO sensor from the front and it ran fine. he couldnt tell whether or not the cat was clogged. I told him if it was, to "gut it". he agreed but he said it will not pass inspection next year. he said if it were a 95, i could get away with it. can anyone help?

ok, fuel filter changed and the cat was gutted. it still has a slight misfire and when i stomp on the gas, it bogs a bit and theres a slight hesitiation. theres a hole in the muffler, too, but the hole has always been there.

check for codes, check the fuel pressure

I have a 99 firebird. I was having the same problem but mine was not all the time. It would miss everytime I drove it but not at a constant miss. Long story short I ended up changing the one of the coil packs and fixed the problem. Shortly after that I had the same problem. Changed another coil pack and fixed it again. 3 months later it happend again. I changed the last pack and so far every thing is ok. Thats been 1 year ago. Mine would miss when you went up a hill of kinda got the car in a strain. Kinda wierd I know but thats what happend to mine. Know the security kicks on when i go to start it and the radio turns off, also the doors wont lock and the windows will not roll down when this happens. Someone told me to sauder something in the wires coming from the ignition switch and it would stop it. I am not sure of that fix though.

yes, the code referred to a "misfire". so far, we changed one of the packs, which was melted, new plugs, new fuel filter, gutted the cat (it was wasted as well) and a new muffler. it still sputters, which indicates a slight misfire still so my mechanic suggested changing the second pack.

yes, the code referred to a "misfire". so far, we changed one of the packs, which was melted, new plugs, new fuel filter, gutted the cat (it was wasted as well) and a new muffler. it still sputters, which indicates a slight misfire still so my mechanic suggested changing the second pack.
I see. Go ahead and change the other coil packs and see if it still misses. If so you might have to change the module. I have ran across that before on one. When you get the other packs be easy with them and do not put any lube or scratches on them. If is still misses and you have to get a module you can take the packs back. Tell them you did not use them and that your mechanic fixed the problem before you gave them the packs. Here on electronics you can not take them back if you install it. Just a thought. Thats what I do as long as I know its not damaged in any shape form or fashion. I have bought some modules from salvage yards. They are a whole lot cheaper than a new one. New one price is crazy. Let me know if this helps

ok, fuel filter changed and the cat was gutted. it still has a slight misfire and when i stomp on the gas, it bogs a bit and theres a slight hesitiation. theres a hole in the muffler, too, but the hole has always been there.

disable the egr valve see if the issue goes away.

why did the converter fail ? could be many components needing testing..

when the plug wires fail you will get coil and ignition module failures. make sure the plug wires have a good resistance and are not with insulating damage.

I dont know why the cat failed. perhaps it was the result of the plugs misfiring. I wish I had the time to work on it myself, and the ability (some of those plugs are a bitch to get to!)

I was going to test drive it but it was blocked by other cars.

why does my car have a rev limiter? can i disengage it?

ok, got the car back and it runs mint!!! i took it out and pinned it and the service light did not turn on. i hear a slight echo, due to the cat being gutted but it rides very smoothly and no more misfire or sputters. now lets see if my gas milage goes up. :)