Computor shows random misfire, 2004 pontiac gran prix

Look at 2004 Pontiac Grand Prix steering column wiring diagram Google Search

Does it stall at idle or going down the highway? How long since a tune-up? Can you check for applicable trouble codes? Some of the national brand auto stores will check codes for free.
Use a gage and check proper fuel pressure. Intermittent issues can be hard to track. If a code is set, maybe freeze frame data will show what was going on when it stalled?

that seems to be the going trend with alot of Grand Prix"s - its the hinge inside the fuel door that has rotted off

Make sure radiator is full and that all hoses are ok. Then make sure that the thermostat is opening and that your water pump is circulating coolant through the radiator which must not be clogged. Till you find issue run your heater full blast with window open to add additional cooling to engine.

Below is the diagram you requested. Best of luck and thank you for using Fixya!
Greg

2004 Pontiac Gran Prix 3.8L

check relay fuse to ur blower under the hood

It could be the crankshaft position sensor. I have a 2001 Grand Prix, and when the crankshaft position sensor went out, the tach would drop to zero, and the car would act like it wanted to stall for about a second.

try changing plugs and wires, if need be remove and clean idle air control valve, cause this is what controls the ideling.

I have a 1998 Sunfire/ son warp the Head by not finding a leak that was the water pump. had head grounded down and reconnected. now i get a PO300 and it a misfire random. took the Ignition coil/ignition control madule to a shop and was test 3 times, first time it showed it failed , they did two more test on it and it passed. At night i turn off all the lights in Garage and sprayed a fine mist of water over the spark plugs and saw some flashing , not much very light on a couple of plug wires. Any one have an idea of what it may be . thanks for reading and i hope someone can give me a good idea thanks again

is something under your hood unplugged have you had any one working on it lately? look for wire unplugged in eng compartment