Hello everybody, I am new in this forum and new to owning Pontiac cars. I thought I would post some info on some issues I had with a 2008 Pontiac Grand Prix 3.8L V-6 I bought for my son a few months ago as his first car. I have it fixed now but thought this might help somebody else if they have a similar problem. I am old school and grew up with vehicles from the 60's and 70's and wasn't familiar with this current type of ignition system. The car has 142K miles. The other day, I was backing it out of the garage when it just died on me. Prior to that, it was running just fine, although a few days earlier I noticed it seem like it did not have as much power to it. I tried to restart it and it turned over just fine but no start. Everything on the car looked to be original including the coil packs, plug wires, and spark plugs. For two days it would not start, then on the 3rd day it started but had an obvious miss in it, and smelled like rotten eggs. I did a lot of reading on various forums including this to understand how these cars ignition system work. As an old Navy aircraft mechanic, I was able to understand the system, and it is a pretty simple ignition system.

I started with pulling the code since after it finally started, I got my first "check engine" light. It gave me a PO300 code which was an random misfire code. I pulled each coil pack and checked the lower prong to see if it was getting 12 volts to the coil pack from the ignition control module with the key to the on position. One of the coil pack prong (for #3-#6 cylinder) was not putting out 12 volts, it was dead, so that indicated to me the ignition control module was bad. I went ahead and replaced the module ($147 at Autozone) and it took care of the problem. Since I hate breakdowns, and due to the age of the car and mileage, I went ahead and put three new coil packs, new spark plug wires, and new spark plugs in it. It now purrs like a kitten. Now I won't have to worry that it may break down on my son. It took me about 20 minutes to pull the coil packs and ignition control module. Remember to number your wires before you do this, so that you know where your spark plug wires go when you re-install them.

Just as a side note: I never received any specific misfire codes pointing to a specific cylinder, just the generic random misfire code. So don't trust that your computer will give you a specific code.