Misfire

Ok i am at a loss. I have a 1999 grand prix se 3.1L 103,00miles ... for about 2 months my car would misfire for a day (service engine soon light on and everything) and then the next day it would be fine, no light no misfire. Well it did this about once a month for about 3 months. Then it got to the point it was misfiring ALL THE TIME. I took it in got new plugs and wires and it is still missing. Hooked it up to a handheld Dino and it said "Misfire #3) i am assuming plug 3. Well after that we replaced the ignition coil pack that #3 was plugged into and no change. It is still missing. PLEASE HELP ME!! Any ideas would be great.

You may have a bad or very dirty fuel injector. If you can get to the injector, remove it and replace it with the one from another cylinder. If the misfire moves then you will need to change the injector with a new one. However, before doing anything remove and clean the connector to the injector and check the wiring to that injector too. This should give you better electrical contact and may take the misfire away. You may also want to consider a professional fuel injector cleaning or putting a can of good quality injector cleaner in the tank.

Welcome to AF!

Thank you very much i will try that and see if it works!

not to jack the thread and all, but I've been having some KR issues as well as lots of random misfires. nothing that sets the SES off, but with a scanner you can see them. I had a cleaning done with the Everwear system (three steps, one additive to the tank, oil treatment, and injector cleaning) but i'm still seeing them occasionally. I'm thinking about replacing the injectors...00 GTP 93K, is this a hard job? DIY?

Replacing injectors is not hard. You will need to drain the fuel lines of pressure, disconnect the fuel lines (requires a special tool available at most parts stores) unbolt the fuel lines from the manifold and the top of the supercharger. Remove and label all injector wiring and then pull the injectors out of the head with the fuel rail attached. Remove the injectors and ready the new ones to be installed. Put new o-rings on each end of the injector and lubricate with petroleum jelly. Then slide each injector into the fuel rail. After they are all done, lubricate the end to go into the head/manifold, seat the injectors into their proper locations and then reinstall in reverse order. Turn on the key so the pump builds pressure and check for leaks. If none start car.

Well ... i took my car in. And it ended up being a fuel injector. It totally freaked me out because the guy took a screwdriver and listened to each injector and then popped one of them and it stopped misfiring. He said that it was a clogged injector and he broke the stuff loose. So then i had him do a fuel line/injector cleaning and it runs LIKE A DREAM!!!!