P0300 cold mornings?
 

Anyone else in colder climates experiencing a p0300 random multiple cylinder misfire in the mornings/at night? I get a constant ses light code P0300 and the freeze frame data points to cold startups water temp 72deg, 1272rpm, 0mph, 5% throttle. Car starts runs and drives fine think the battery might be going as the voltgauge is reading 11.8 volts before I start it.

I've seen cases where a bad injector causes this. though usually there's another fault for a specific injector.

Ever figure anything out with this? I am having the same issue on cold nights after work...

Are you running a cold air intake?

I think this is common, and due entirely to ECU logic in detecting misfires -- especially if random.

If you have uprev, you can change a few settings to make it less likely to set off (crank drag, DTS off).

Yes I am. Gen 3's

P0300 - Random Misfire

Indicates multiple cylinders are misfiring or the ECM cannot identify which cylinder is misfiring.

Possible Causes:
Camshaft position sensor (CMP)
Low fuel (less than 1/8 tank)
Stuck open EGR valve

YMMV

Full tank of gas... how would I test the other two?

Also never saw this cel before my cai was installed... coincidence?

I'm guessing in your case its a lean miss from either a vacuum leak or the MAF sensor readings are off from the CAI.

If the former, you just have to trace it down; if the latter, only a tune (or turning off the DTS code trip option via uprev) can fix it.

The P0300 Cel I had occurred right after a rain storm both times. Idle was rough as well. The next morning the Cel was gone. I suspect wet filters from my Gen 3? Perhaps some rain water reached the filters while parked. I no longer drive in heavy rain storms.

I am thinking about getting sine hydro shields to prevent that.

Diagnostic, repair, and maintenance info are in the FSMs if you want to DIY. Otherwise it means a trip to the mechanic.

Since you have installed a CAI, I would investigate in that direction first.

Haha wow an old one of mine i never updated in my case it was a disintegrated engine bearing due to oil system failure and the amount of banging the crank was doing was triping knock sensor so it THOUGHT it was misfiring. Then the crud plugged the cam actuators and 2months and three trips to the dealer later new motor.

Damn! I sure hope that's not what is going on with my car (currently in the shop investigating this same code and not finding anything). Was your idle higher when the code came on then went back to normal when it went off? That's what mine does.