Resetting a Misfire (P0301) code?

[blazindave]

Okay, I was driving along and my SES light started blinking, and the car was runny really crappy - Go to Autozone and they give me a P0301 code for Cylinder 1 misfire. Buy new plugs and replace the front 3 (I am out of town, I will have to change the rears next weekend)... Car is running smoothly now, but the SES light is still on. I assume it is just staying on because it still has the P0301 code saved in there? How would I reset it - or at least make the SES light go away? I want to be able to see right away if the new one gets fouled quickly indicating some other problem...

[BNaylor]

Here's a field expedient method to reset PCM:

Remove only the battery positive cable.

Insert key in ignition and take key to full engine start position and hold there for at least 1 minute. (Of course, engine will not start and no instrument lights).

Take key back to off, however, it will not remove at this time and be stuck. No problem.

Next re-connect battery positive cable. You will hear relays chatter.

Now turn key forward and back. It will now remove.

Finally, start engine. SES light should be off and all DTC error codes cleared. PCM should now be in re-learn mode.

Good luck!

Or take it back to Autozone and let them clear the SES light.






Thrasher CAI, DHP v1.0 PCM, SLP Headers,
3.25 SC pulley, CAIT GMAF, 2.5 DP/Hi-Flow CAT,
u-bend delete, 160 TS, ZZP Stage 1 72mm TB,
TB spacer, MSD 8.5mm wires, Autolite 103,
Goodyear Gatorback Serp. & SC Belt,
Nitto NT555R Drag Radials
1/4 ET: 13.210 sec. @ 104.490 mph
0 - 60 ft: 1.945 sec.

[blazindave]

update:

code went out on its own.

the guy at autozone said that they couldn't just clear the code though...

so now I don't know if the code is still stored or not, but I will be able to tell if it misfires again I guess...

thanks for the help though!

I'm a bit concerned, as the other 2 of the fronts were AC Delco Iridiums (just like the ones that I bought) but the one that was fouled was not - it was an AC Delco, but I don't know what kind. So I am thinking it is one of 2 things: either it was just a crappy plug and thats why it fouled and I shouldn't have anything to worry about now. OR (and I feel like its this, but I hope not) there is a some other problem that is letting oil into cylinder 1, and the previous owner knew about it and just replaced that one plug as necessary. This would probably explain why I am burning oil... and it would probably be a very costly repair I guess, right? like a piston ring or something maybe?

[Ripn12s]

I would think having a compression test would help you find out. Just a suggestion, never done a compression test but it seems like a good start.

[BNaylor]

Originally Posted by blazindave

update:

code went out on its own.

the guy at autozone said that they couldn't just clear the code though...

so now I don't know if the code is still stored or not, but I will be able to tell if it misfires again I guess...

thanks for the help though!

I'm a bit concerned, as the other 2 of the fronts were AC Delco Iridiums (just like the ones that I bought) but the one that was fouled was not - it was an AC Delco, but I don't know what kind. So I am thinking it is one of 2 things: either it was just a crappy plug and thats why it fouled and I shouldn't have anything to worry about now. OR (and I feel like its this, but I hope not) there is a some other problem that is letting oil into cylinder 1, and the previous owner knew about it and just replaced that one plug as necessary. This would probably explain why I am burning oil... and it would probably be a very costly repair I guess, right? like a piston ring or something maybe?

How much oil is being consumed? Could just be bad intake or exhaust valve guide seals on that respective cylinder.

On the suspected bad spark plug, which specific AC Delco was it. I've been having bad luck with AC Delco Platinum Rapidfires in one of my other "W" bodies. Some form of manufacturing defect.








Thrasher CAI, DHP v1.0 PCM, SLP Headers,
3.25 SC pulley, CAIT GMAF, 2.5 DP/Hi-Flow CAT,
u-bend delete, 160 TS, ZZP Stage 1 72mm TB,
TB spacer, MSD 8.5mm wires, Autolite 103,
Goodyear Gatorback Serp. & SC Belt,
Nitto NT555R Drag Radials
1/4 ET: 13.210 sec. @ 104.490 mph
0 - 60 ft: 1.945 sec.

[blazindave]

The cylinder 1 plug is labeled AC Delco 41-940.

The ones I bought were the AC Delco Iridiums, 41-101.

According to Delco's website, the 41-940 is recommended for the GP SE and the Grand Am SE and Grand Am GT, but not the GP GTP... for the GTP the Iridium 41-101's are recommended...

It consumes a considerable amount of oil - I generally have to put in a quart about every or every other time I fill the gas tank, which is about once a week...

What kind of testing should be done to check the intake/exhause valve guide seals? Is this something I can diagnose or should I take it to a shop?

[BNaylor]

Originally Posted by blazindave

The cylinder 1 plug is labeled AC Delco 41-940.

The ones I bought were the AC Delco Iridiums, 41-101.

According to Delco's website, the 41-940 is recommended for the GP SE and the Grand Am SE and Grand Am GT, but not the GP GTP... for the GTP the Iridium 41-101's are recommended...

It consumes a considerable amount of oil - I generally have to put in a quart about every or every other time I fill the gas tank, which is about once a week...

What kind of testing should be done to check the intake/exhause valve guide seals? Is this something I can diagnose or should I take it to a shop?

Thanks for the feedback. The AC Delco Iridiums are the best ones to use if you're stock. The regular platinum is the AC Delco Rapidfire #14.

BTW - the 41-940 could be used from what I gather. I've got a Olds Alero GL2 with the same 3.4L V6 as the Grand Ams. I have the AC Delco Iridiums 41-101 which are the recommended Iridium plug for the 3.4L too. How's that for being confusing.

To detect bad valve guide seals, low compression or bad head gaskets it's probably better to take it to a shop. They can run a cylinder leak down test. You could do the compression testing on your own but you'll need a compression tester. There's a static and dynamic test.

The major problem will be taking a reading on the rear bank of cylinders. PITA as usual.








Thrasher CAI, DHP v1.0 PCM, SLP Headers,
3.25 SC pulley, CAIT GMAF, 2.5 DP/Hi-Flow CAT,
u-bend delete, 160 TS, ZZP Stage 1 72mm TB,
TB spacer, MSD 8.5mm wires, Autolite 103,
Goodyear Gatorback Serp. & SC Belt,
Nitto NT555R Drag Radials
1/4 ET: 13.210 sec. @ 104.490 mph
0 - 60 ft: 1.945 sec.

[vamc]

Originally Posted by bnaylor3400

Here's a field expedient method to reset PCM:

Remove only the battery positive cable.

Insert key in ignition and take key to full engine start position and hold there for at least 1 minute. (Of course, engine will not start and no instrument lights).

Take key back to off, however, it will not remove at this time and be stuck. No problem.

Next re-connect battery positive cable. You will hear relays chatter.

Now turn key forward and back. It will now remove.

Finally, start engine. SES light should be off and all DTC error codes cleared. PCM should now be in re-learn mode.

Good luck!

Or take it back to Autozone and let them clear the SES light.






Thrasher CAI, DHP v1.0 PCM, SLP Headers,
3.25 SC pulley, CAIT GMAF, 2.5 DP/Hi-Flow CAT,
u-bend delete, 160 TS, ZZP Stage 1 72mm TB,
TB spacer, MSD 8.5mm wires, Autolite 103,
Goodyear Gatorback Serp. & SC Belt,
Nitto NT555R Drag Radials
1/4 ET: 13.210 sec. @ 104.490 mph
0 - 60 ft: 1.945 sec.

Bob-i heard that autozone can not reset it with there scanner. they told me that it is aginst the law or something. Does this sound right, or where they wrong?

[BNaylor]

Originally Posted by vamc

Bob-i heard that autozone can not reset it with there scanner. they told me that it is aginst the law or something. Does this sound right, or where they wrong?

It depends. It not against the law just their corporate policy. But the guys we have are cool. They've reset for me. They use Actron CP scanners with reset capability.

I don't mess with Autozone when it comes to scanning. I've got 2 Actron Scanners of my own and Autotap on a laptop computer. However, when all else fails the field expedient method above works if you do not have a scanner, at least in a GM "W" body.







Thrasher CAI, DHP v1.0 PCM, SLP Headers,
3.25 SC pulley, CAIT GMAF, 2.5 DP/Hi-Flow CAT,
u-bend delete, 160 TS, ZZP Stage 1 72mm TB,
TB spacer, MSD 8.5mm wires, Autolite 103,
Goodyear Gatorback Serp. & SC Belt,
Nitto NT555R Drag Radials
1/4 ET: 13.210 sec. @ 104.490 mph
0 - 60 ft: 1.945 sec.

[vamc]

Ok. cool. now i think its time to go to bed, work tomarrow.