Multiple Random Misfire/Fixed itself?

[Androideka]

Hey guys, here's one for you. I have a 2015 Camaro V6 with the LFX engine. 5-6k OCIs, well maintained in general and doesn't have any ongoing issues

Yesterday I get off the highway after some spirited driving and a few stop lights later I get a super rough idle, blinking check engine and "Service StabiliTrak" message on the dash. I pull over, hookup my $20 code reader and I have a pending P0300. Checked the oil, coolant, topside connections that I can see with the hood open, all good.

After starting the car back up, it's like nothing happened, runs perfectly. No CEL, no rough idle, acceleration is normal, etc. I've driven about 50 miles since, and no problems. Is this anything to be concerned about? Just a glitch?

 

[Kira]

I've driven about 50 miles since, and no problems.

Did you drive these 50 miles as "spiritedly" as you did yesterday?

Perhaps a cylinder head temperature sensor was maxed out and defaulted (signaled for a default) to the 'main brain' such that fuel delivery was reduced?

Other sensors like MAF and MAP, if there is one, might be aging or dirty.

 

[GON]

Hey guys, here's one for you. I have a 2015 Camaro V6 with the LFX engine. 5-6k OCIs, well maintained in general and doesn't have any ongoing issues

Yesterday I get off the highway after some spirited driving and a few stop lights later I get a super rough idle, blinking check engine and "Service StabiliTrak" message on the dash. I pull over, hookup my $20 code reader and I have a pending P0300. Checked the oil, coolant, topside connections that I can see with the hood open, all good.

After starting the car back up, it's like nothing happened, runs perfectly. No CEL, no rough idle, acceleration is normal, etc. I've driven about 50 miles since, and no problems. Is this anything to be concerned about? Just a glitch?

I suspect you may have corrosion in a coil and/ or wire/ boot plug.

For me, I would replace the coils, wires/ boots, and spark plugs (although I don't think you have a failing spark plug). More likely than not, you will have solved your intermittent misfire that appeared under load.

If you don't want to replace the coils, cleaning the contacts at the coil/ boots/ wires with contact cleaner, and spray deoxit on the contacts is a less costly alternative method.

 

[bullwinkle]

Could have even been bad fuel, messing with the air/fuel mixture & causing misfires. A tankful of Top Tier, or even splurge on Shell Premium, with a nice shot of Techron or other PEA containing additive, has fixed issues for me in the past (that even a dealer couldn’t fix)! A GM “Service Stabilitrak” message can mean just about anything…

 

[Androideka]

Did you drive these 50 miles as "spiritedly" as you did yesterday?

Perhaps a cylinder head temperature sensor was maxed out and defaulted (signaled for a default) to the 'main brain' such that fuel delivery was reduced?

Other sensors like MAF and MAP, if there is one, might be aging or dirty.

I got the revs up to nearish redline twice since while going down on-ramps and such, just to see if it caused any problems, which it didn't. Otherwise just mostly a normal mix of city/high way driving to and from work. I think I'll clean the MAF - I've had problems with MAFs in this car since I got it, but they've caused lean codes not misfires and this MAF has so far been trouble free for 3 years

 

[Androideka]

I suspect you may have corrosion in a coil and/ or wire/ boot plug.

For me, I would replace the coils, wires/ boots, and spark plugs (although I don't think you have a failing spark plug). More likely than not, you will have solved your intermittent misfire that appeared under load.

If you don't want to replace the coils, cleaning the contacts at the coil/ boots/ wires with contact cleaner, and spray deoxit on the contacts is a less costly alternative method.

That's true, I'm at 76k miles on the car and about 15k on these spark plugs, but the rest of the ignition system is original. I'll try cleaning them like you said first, since the coil packs are $60 a piece on RA. If there was a bad coil/plug/boot, would the computer be able to pick up that just that cylinder is misfiring? If my understanding is correct, my CEL was for a misfire moving between cylinders, but I could be wrong

 

[GON]

I got the revs up to nearish redline twice since while going down on-ramps and such, just to see if it caused any problems, which it didn't. Otherwise just mostly a normal mix of city/high way driving to and from work. I think I'll clean the MAF - I've had problems with MAFs in this car since I got it, but they've caused lean codes not misfires and this MAF has so far been trouble free for 3 years

The issue you have is common on GM V6 passenger vehicles. I have seen it multiple times and it was always a coil/wire/boot.

The way to test is to put the engine under a heavy load. This is easiest achieved when going up a long incline. I suspect if you put the engine under load going up a long incline at a decent grade- you will easily duplicate the misfire.

 

[GON]

That's true, I'm at 76k miles on the car and about 15k on these spark plugs, but the rest of the ignition system is original. I'll try cleaning them like you said first, since the coil packs are $60 a piece on RA. If there was a bad coil/plug/boot, would the computer be able to pick up that just that cylinder is misfiring? If my understanding is correct, my CEL was for a misfire moving between cylinders, but I could be wrong

Sorry, I can't recall if the flashing cel on a GM v6 passenger vehicle triggers which coil/cylinder is erroring.