Pontiac Repair: 1996 Pontiac Grand Prix, pontiac grand prix, grand prix 3

Question
3.1 engine  I wrote you a few days ago saying that I was tired of changing parts on this motor and you suggested that I have it diagnosed by a pro.  I forgot to tell you that after the G M dealer here in Lincoln NE, changed the coil first reassuring me that that  would fix the problem and then the problem started back again a week later and i took the car back in and then they said it was the plug wires and changed them and the problem is still there..  I can change parts somewhat cheaper than the dealership....... I just need to find out my problem with the engine. I dont mind paying them if they fix the car but I think this is somewhat  trial and error at my expense.  Like I said when the service engine lite comes on and the car runs rough  I take the wires off the first coil closest to the drivers side and there is abslutely no spark..  The ignition module is very costly and I hate to replace it if its not bad    SUGGESTIONS?   Bob in Lincoln NE  (402)-476- 2220

Answer
Ok, Here is what you can do to check to see if it really is the module. Swap places with 2 of the coil packs. If the next time that it acts up, you still have no spark from the coil closest to the drivers side, you have a bad module. If that coil is still working but the original one from that position is not working, the coil is bad.
Here is what usually happens when you have secondary ignition problems:
1) Your plug wires get cracked or develope high resistance. The spark has to go somewhere so it either arcs to another wire or to a ground on the engine(valve cover, dipstick, etc.) Or it travels down the coil tower to a ground.
2) Once the spark starts to travel down the coil to ground, it creates a carbon track. This is like having a high speed circuit to ground and eventually it will burn its way into the coil. You may not be able to see it but there is a crack or hole that goes into the coil windings.
3) No that the coil fires inside itself, it doesn't really have a grond for the spark to go to so it goes into the module. It doesn't take much of this to damage the module since the coil put out about 80,000 volts.
It is very common to have a module fail after a coil or wire failure. I always let the customer know this so that they can decide for themselves if they want to do the whole repair now or take a chance on doing half of the repair.
Hope this helps you out. If you need more info or have any other questions, let me know.