Pontiac Problems? Ask a Mechanic for Answers ASAP
I'm sorry the Tech you requested was unavailable to assist you today. It appears that Tech is currently "Offline". Now that his 15 minute "request lock" has expired, hopefully I can be of some assistance in his place...There are a few different things that can cause a single-cylinder misfire. If the vehicle has 230k on original plugs, this is definitely the first place to start. Remove the plug and inspect for any cracks and/or worn diode. If there are any doubts, replace all the plugs. If the new plugs do not solve the problem, next check the ignition coil. Make sure the coil is sending good, strong spark to the plugs. If the coil checks ok, next check the injector. With the engine running, remove the electrical connector to the injector for cylinder #3. The engine should respond with a worse idle. If not, the injector will need to be replaced. If the injector checks ok, an intake air leak test around cylinder #3 will need to be done and then ultimately, a cylinder compression test. Please remember to leave a rating using the star rating system at the top of this page or accept the answer so I may be credited for this Q&A. You can ask follow-up questions any time, even after you rate or accept.