cold engine misfire

[Firebird45331]

I have a 95 firebird with a 3.4. When I first start the car it misses until I get about two blocks or so and it smooths out. I replaced the plugs, wires, and coils which seemed to help at the time for about two weeks, but then it's gotten colder out and it's back.

[auto666]

Re: cold engine misfire

its the middle injector on the passenger side it a common problem with the 3.4s in camaros. I believe its cause by the heat from the egr being right there runn a injector cleaner every other tank and it help keep it to a min or you could just change your injectors accel offers a set preaty cheap no idea about quality though

[Firebird45331]

Re: cold engine misfire

I got some fuel injector cleaner at autozone. I left my car running while I went in it was missing and sputtering like hell. Then by the time I came out it was smoothed out and running perfectly. I hope the cleaner makes a difference.

[Meatyshells]

Re: cold engine misfire

try seafoaming your car, it helped a little with my ruff idl

[Firebird45331]

Re: cold engine misfire

just noticed tonight that while it's missing I'm getting a strong fuel odor inside the car. Would a bad injector cause that? Also my car doesn't warm up either. I don't know if that's related or just another problem that needs fixed

[BLLDOGG]

Re: cold engine misfire

when you have a misfire, your not burning the fuel put into the engine so it goes into the exhaust

[Firebird45331]

Re: cold engine misfire

was just doing some research and found a post where the fpr was causing the same symptoms as mine minus the hard start. I don't have any trouble starting it, but after a few hours of sitting it'll run rough when I start it. Can a fpr cause a miss without hard starts?

[landj]

Re: cold engine misfire

Mine does the same thing. When it's cold (below 40F or so) it will start right up, but the idle is a little erratic. I give it a little gas and it accelerates fine (doesn't miss). If I stop within a half a minute or so, same erratic idle, but if I drive a little farther it runs fine.

I wouldn't think that the fuel pressure regulator would change with temperature. I'll see if i can get out there and check on that this weekend to see if the fuel pressure changes as it warms up.

[landj]

Re: cold engine misfire

just noticed tonight that while it's missing I'm getting a strong fuel odor inside the car. Would a bad injector cause that? Also my car doesn't warm up either. I don't know if that's related or just another problem that needs fixed

My car warms up fine. Sounds like your thermostat isn't working.
After you start the car, feel the upper radiator hose and see if it is as warm as the engine when you first start the car. The engine should get warm while the radiator hose stays cool near the radiator, then the thermostat will open, and then the radiator hose will get warm (hot). If your car isn't warming up at all, I'd say its most likely a stuck thermostat.

[Firebird45331]

Re: cold engine misfire

well today I start the car and it was running rough and missing as it usually does. I go inside come back out and the car has stalled. i start it back up and it's running really crappy. All the way into work it was bucking and missing. Today when I leave work same thing. I drive to autozone to see if they can check my codes, which they said they can't becaue it's a 95 pontiac and it had an obd I computer with an obd II connector. I go outside to leave. Start the car and it runs fine.

[Vanquish]

Re: cold engine misfire

I read that you did change your spark plugs/wires and coil packs. I think you should test each of your coil packs for a good spark and make sure they are all working properly.

When you are standing directly in front of your car, looking at your engine, check the first coil pack closest to you (I'm willing to bet it has fouled out) and if it is fine, continue to check the other two. When coil packs are going out it will sometimes be hard to start your car (it will take a few spins of the flywheel) and then usually erratic idle or sometimes nothing at all and it will run fine some of the time.

Also, if it proves to not be your coil packs, make sure you have no vaccuum leaks, mainly by your pcv valve, and also check this valve to make sure it doesn't need to be replaced.

good luck and I hope you find and fix the problem.

[Firebird45331]

Re: cold engine misfire

Thanks, the coils are only 3 weeks old. it wouldn't be bad would it? would a fuel pump, egr, or fpr cause anything as erratic as this?

[Vanquish]

Re: cold engine misfire

Yes. Clogged fuel filter, dirty egr valve would cause this as well........though you would have a SES light on........and I don't remember you saying anything about having a check engine light on. Then again, I do forget everything I just read every 5 minutes.

And yes, even though the coils are 3 weeks old, they(one of them) could already be bad. I've change my front coil pack as much as 4 times in less than 6 months. It's just a touchy subject with the mid 90's f-bodies from what I understand.

[Firebird45331]

Re: cold engine misfire

I've already done the fuel filter. I'll recheck my coils. I think my ses light is disconnected or burnt out. it doesn't light when I start my car.

[Firebird45331]

Re: cold engine misfire

just so happened I had a bad sparkplug and the crank sensor was shot. That was causing my miss