misfire problem HELP!!! [Archive] - GrandAmGT.com Forum


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03-21-2005, 06:33 PM
I have a 99 se 3.4 and it seems when the engine bay is fully saturated with heat and im cruising along between 1200 and 1900 rpm the engine will have slight random misfires, and it also does it when there are grade changes in the road, i.e. when the road is sloping upwards, it will only misfire once when i start climbing the hills and thats when the load is placed on the engine at the bottom of the hill. wtf is going on?? i checked the plugs replaced the wires and its sitll doing it. has anyone else had a problem like this with their 3400? if so and u found the problem let me know, or if you have any other knowledge about this problem. thanks in advance!!!

04-06-2005, 10:35 PM
I have a 92 GA GT with the 3.3L and it has the same problem. I am not sure what the problem is but I'm new here and I'm going to add a thread to see if anyone can help me. If you find anything out, I'd appreciate it if you could let me know and I will do the same!

04-07-2005, 08:29 PM
I will tell you, I am a tech at a Pontiac dealer and I see lotts of misses on 3.1's, 3.4's and 3.8's. 90% of the time it is the fuel injectors causing it. Dirty injectors cause a lean missfire causing what your talking about, a lack of power. Also, corroded terminals on the coils cause this. Other then that, a spark plug could have a hair line crack in it. This will also do what your talking about. To clean the injectors, go to a GM dealer and get some fuel detergent and run that and see what happeneds. It is $20 for the bottle but it works really good. If that dont work keep working at it, you'll find it. Now, the 3.3L for you orange, 3.3's naturally run rough, but if it is really running rough there is one thing that I've had luc with, and thats cleaning the MAF sensor off. Now, to do this, remove the MAF and get some carb cleaner and some electronics cleaner. Spray off the little wires on the MAF with the carb cleaner first and then with the electronics cleaner. Clean it once from both sides. Before the cleaning the wires will probably be black and after they should be silver or white. DO NOT TOUCH THE LITTLE WIRES WITH ANYTHING, THEY WILL BREAK AND THAT IS A LOT OF MONEY!

I hope this helps you 2 guys with whats going on with your cars.