Code P0301

Hey all
Got a P0301 code. The book says Cyl no1 misfire. The check eng light is off now. So what does it mean and how do I fix it?
Thanks

Change the spark plug and plug wire first. If that does not fix it you will need to look at the coil and the injector. Spark plug and wire change will usually fix the problem.

The plugs are only about month old. Use them and change the wires or change them both?

Check the gap on the plugs. If you don't have the proper gap it can cause a misfire then change the wires. What type of plugs did you use? If you used Bosch go back to AC or another brand.

I put AC back in. I used the orignal AC plugs. I just found out that the car got stuck in the snow. I figure that some moisture got up in the engine compartment and caused the misfire. I think I'm going to clear the code and wait and see if it happens again. If they can keep it out of the snow bank I think I"ll be alright. Any ideas on this? It's been running good. The check engine light is not on anymore.

Sounds like a plan to me as moisture can cause misfires. You may want to put some additional dielectric compound inside the spark plug boots which will keep moisture out.

Never thought of that. I knew someone would here would have an idea. Thanks a bunch.
Zirb

Check the gap on the plugs. If you don't have the proper gap it can cause a misfire then change the wires. What type of plugs did you use? If you used Bosch go back to AC or another brand.

Do the Bosch plugs really make that much of a difference? I replaced my ancient plugs in September with Bosch platinums, and they certainly didn't give much increase in perfomance. Now, cylinder 4 is misfiring. I've already tried changing the plug wire, no luck. Maybe changing all six back to AC's would help?

Other than the coils, what else can cause a misfire?

Is it a 3.1 ?

Is it a 3.1 ?

Yes, a 97 SE V6

I have found a few that the terminal on top of coil pack was just corroded,, cleaned with steel wool and penetrating sray ,, cleared up the miss fire ,,just a thought ,,hope it helps

I have found a few that the terminal on top of coil pack was just corroded,, cleaned with steel wool and penetrating sray ,, cleared up the miss fire ,,just a thought ,,hope it helps

Yeah, some of the towers had a bit of corrosion when I changed the wires in Sept- I scrubbed it all off with Scotchbrite, and smeared them with diaelectric grease when I put the new wires on. The posts still look to be in pretty good shape. The wires came off much easier when I was checking them today then they did last time!

No chance its sipping anti freeze ? Then thinking prolly not on # 4

No chance its sipping anti freeze ?

You mean like through a blown head gasket? Don't know- how would I check?

no..I was thinkin intake gasket

did any plugs look cleaner than the others ?

no..I was thinkin intake gasket

I have no idea. I wouldn't have guessed an intake manifold leak could introduce antifreeze. You mean the gasket between the plenum and the tops of the valves? Seems if that's it, it shouldn't be tooo tough to replace....

did any plugs look cleaner than the others ?

Don't know yet- I'll pull the plugs tomorrow morning.

I can't remember their being coolant near centre ports( I think you said # 4) that would be a centre cyl. checking colour of plugs is a good idea. if it is a coil you should have a miss on both cylinders attached to that coil.

I can't remember their being coolant near centre ports( I think you said # 4) that would be a centre cyl. checking colour of plugs is a good idea. if it is a coil you should have a miss on both cylinders attached to that coil.

So if the coil was at fault, cyl 1 would definately be misfiring too? The scan tool at the auto parts store only showed P0304.

I would like to see misfires in the data stream of scanner, they hold a history of misfires along with real time. it makes it alot easier to pin point than just relying on codes

If you have a misfire the first thing I would do is change the plugs and wires. These are the two most common causes of misfires on cars. Since it indicates Cyl. #4 then pull the plug and check it. I doubt you have an intake problem at the present time especially if you are not seeing any coolant loss, chocolate colored oil or a plume of white smoke out the exhaust.

One other thing to try if the plug and wire does not correct the issue is to move the #4 injector to another cylinder and see if the misfire moves. If the misfire goes to that particular cylinder then the injector is bad.

As for the Bosch plugs they usually don't work well in Pontiacs. I have a GTP and left them in for about 5K miles before changing them to autolites. I had a misfire and once I replaced the plug it went away.

Replaced the wires and plugs today (only took an afternoon- last time took three days!). The wires I replaced in Sept were still under warranty- so a brand new set of free wires from Advance Auto. Then new plugs are the OEM AC's. The three month old Bosch's all looked fine. Took it out this evening, got it up to operating temp, and no sign of misfire. So far, so good! Tomorrow, back to Advance to use ther scanner to clear the misfire code, and hopefully reset the check engine light.

Thanks for the help, it is much appreciated! AF is terrific.