P0300 suggestions?

[jchristena]

Mods are in my signature but I replaced the clutch about 600 miles ago. Did a crank relearn and still get a P0300 random misfire every couple of days. Plugs are TR7IX, gapped at .028 and have about 2k on them at most. I'd appreciate some suggestions on things to check.

 

[2011 gtcs]

Did Lund racing have any suggestions? Inspect all the spark plugs for any cracks in the porcelain, did you install a aftermarket flywheel

 

[raustin0017]

If you reset and the code & it keeps coming back this is what I would do:
Pull the plugs and double check gap.
Check for any vacuum leaks.
Check battery, even if the battery will start the car it could be down and not able to hold the load and needs to be replaced. This is real common for the C0300 misfire.

If the above all checks out it points to fuel pressure.

Just my 2 cents...
Good luck

 

[jchristena]

Thanks guys. I'll check that stuff. The tune has been on the car for 6 mo w/ no problems..but I was going to reach out to Lund Racing and see if they had any suggestions.

The car does start fine and the battery is 3 months old. I'll still get a load test put on it to be sure though.

I should point out, the problem doesn't happen under load or at RPM like I see for some other people. It happens when the car is idling within the first 5-10 seconds after a cold start.

 

[jchristena]

Did Lund racing have any suggestions? Inspect all the spark plugs for any cracks in the porcelain, did you install a aftermarket flywheel

Yes, its the flywheel that came w/ the DYAD kit.

 

[2011 gtcs]

Yes, its the flywheel that came w/ the DYAD kit.

And the misfire was still going on before the new flywheel?

 

[jchristena]

And the misfire was still going on before the new flywheel?

No. Misfire started about a week ago. I didn't do a crank relearn after the clutch because it didn't throw a code. When the code started on Monday, I did the relearn thinking that would fix it. But...no codes for about 600 miles on the clutch so it doesn't seem related to that AFAIK.

 

[2011 gtcs]

No. Misfire started about a week ago. I didn't do a crank relearn after the clutch because it didn't throw a code. When the code started on Monday, I did the relearn thinking that would fix it. But...no codes for about 600 miles on the clutch so it doesn't seem related to that AFAIK.

have you tried swapping in new plugs? Its always hard when you get a random misfire to diagnose the issue. But I know Lund recommends Brisk GR12YS plugs so maybe give those a try

 

[jchristena]

have you tried swapping in new plugs? Its always hard when you get a random misfire to diagnose the issue. But I know Lund recommends Brisk GR12YS plugs so maybe give those a try

Seems like it might be easiest just to swap them. I could have sworn they initially recommended the plugs I'm running now. I'll clarify w/ them and then order them. I appreciate the suggestion.

 

[jchristena]

FWIW I just got this back from Johnny Nardi:

The ones I would say to do would either be BR7EF NGK plug or TR7IX NGK plug Gapped @ .028”

 

[2011 gtcs]

FWIW I just got this back from Johnny Nardi:

The ones I would say to do would either be BR7EF NGK plug or TR7IX NGK plug Gapped @ .028”

I have never worked with him, when John Lund Jr was tuning my 13 gt500 on E85 he told me to run the brisk plugs, But it's not a big deal, either way I would try a fresh set of plugs and see if it helps.

 

[jchristena]

I have never worked with him, when John Lund Jr was tuning my 13 gt500 on E85 he told me to run the brisk plugs, But it's not a big deal, either way I would try a fresh set of plugs and see if it helps.

Yea, Jon II has always done me right. I absolutely trust their judgement.

 

[JimIII@jdm]

P0300 is random multiple cylinder misfires at start up. Typically fouled or damaged plugs or ignition coils can cause this. You can also get this code after a clutch but doing the crank relearn should have fixed it. Being it didn't come on right after the clutch I agree and don't feel it has anything to do with that.

Start with the plugs, when removing the coils inspect them for any water or moisture that will cause the coils to go bad. Being that it's just a P0300 and your not getting any other specific cylinder misfire codes I think it's most likely just your plugs.

The IX plugs are very sensitive to fueling and can foul out quickly. If you don't drive the car much or idle it for too long they can foul out. Also using octane booster will discolor the plugs and leave sediment on them that can cause misfiring. So DONT use octane booster or additives.

Put a fresh set of plugs in and call us in the morning

JimIII

 

[jchristena]

I appreciate all of the input...truly I do. I pulled the plugs just now and they all look like this. I've talked to a buddy and he said they looked fouled to him and that the tune is overly rich...which I KNOW its a safe canned tune.

Thoughts?

 

[Ghoust]

I chased down a P0300 about a year ago. In the end it was the plugs. I put in TR7iX iridiums gapped at .29 and I haven't seen a CEL since.

 

[03kbredfire]

I also chased this code through the gamut of possibilities. Ended up data logging and found the tune was too hot for octane support available. Any change that you made could have changed things just enough or fuel may have changed for the winter blend. I would data log and have tuner check against too much timing for given application. I was quite surprised that a minor timing change helped resolve the p0300 issue set that I would see every few days. Datalog.

 

[Beercules]

The only time I tried brisk plugs I gave up after a couple of the original shipment and a couple replacements showed up bad. Might try ngk if you haven't already.

have you tried swapping in new plugs? Its always hard when you get a random misfire to diagnose the issue. But I know Lund recommends Brisk GR12YS plugs so maybe give those a try

 

[kwarnerjr]

My car threw a p0300 last week...I’m on a Steeda tune. I stopped by their FL location and they had me switch to brisk plugs gapped 30-32. Since the switch the car has thrown the code 1 time (about 2 hours after the switch). It’s been 4 days and about 120 miles and no new codes. Hopefully I won’t see another code but if I do I’ll be on the data logging train to try and diagnose.

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