Pontiac Repair: 99 Grand Prix - engine rough, kv output, autozone

Question
I have a 1999 Grand Prix GTP (3.8L with supercharger), that within the last 5 to 10 starts has been idling rough (missing), for about 5 minutes then it is ok. The last time this happened the "service engine soon" light came on. Can you please give me some suggestions that I might try.

Thanks
Jeff

Answer
Hi Jeff
I would FIRST have the SES (Service Engine Soon) light diagnosed.
Most national repair chains (Midas, Meineke, Pepboys, etc..) offer this service free.
Also MOST Parts stores (Autozone, NAPA, Advance) also offer this free.
From there they MAY give you an idea.... IT sounds like it is PROBABALLY a missfire, setting a misfire code (P0300).
I would suggest to you, after diagnosed SES, a Major tune up (Plugs, wires, fuel filter, air filter, Injectors cleaned and throttle body cleaned)
Have the coils tested fro proper resistance and kv output.
A Misfire can be Ignition cause, Fuel caused and lastly Engine mechanically caused.
This is why I recommend taking care of 2 (Ignition and fuel) before worring about mechanical.
I hope this helps.
Get the SES light diagnosed first.
Good luck
Pawl