: p0308 misfire, trying to find problem

09-01-08, 05:38 PM
so i bought an obdII scan tool... the scan tool tells me there is misfire on cylinder 8 when the car itself just tells me a p0300 misfire code. I pull the plug wire on cylinder 8 and nothing in the car changes.... any other plug wires i pull, the engine changes idle motion.

I changed the plug wire from another cylinder, still a problem

I change the plugs from cylinder 8 with another from another cylinder, still a misfire.

When I pull the plug and get close to grounding, there is no spark coming out of the plug.

I pulled out the ignition control module, can I interchanged the numbered coil housings with another? are they the same since they are all numbered for each cylinder? just wondering if i should do this before I attempt it.


09-01-08, 08:00 PM
ok, so i changed them anyways.... the car noted a p0300 misfire code, my obdII scan tool noted a p0308 misfire in cylinder 8. I swapped the ignition coils around and a different cylinder misfired... so i replaced the broken ignition coil and the misfire is gone, car running smooth again.

09-01-08, 08:16 PM
:thumbsup: That's what I would have suggested.

09-16-08, 07:41 PM
i get a pcm 300 misfire code i just changed the wires and plugs, i did have bosch split tip platinum,but changed to a platinum autolite.car did have pcm 420 code for the longest but it cleared out with the change of wires can anybody help my ?

09-16-08, 08:32 PM
Your car uses a set of ACDelco Platinum Professional spark plugs, #41-950. That's what it likes to run on. www.rockauto.com . Check your plug wires for arcing by removing the engine cover and looking at the entire wire set in a dark area.....any arcs or sparks ? Make sure the wires are connected to the coil pack as indicated below: It makes a BIG difference in performance.

Click and scroll in.............

09-17-08, 04:35 PM
wires are new, just changed i rechecked them and all are in the right order. now the pcm 300 code comes up as history and the service engine soon light is off . but the car runs like sh.......

09-17-08, 07:16 PM
wires and plugs are new not oh i put them on 10k miles ago i purchased them sat. installed sunday. today the pcm 300 code is history and the ses light is off but cars still runs like a p.o.s.