P0300 under WOT and low temperatures
 

So... got P0300 last night when going WOT.
Looks like I'm having popping noises only on WOT and only during cold nights. Ever since winter started I'm getting random misfires and the car loses power during the popping/backfire sound.

EDIT: The root cause has been found. It's the actual Methanol system on cold weather producing problems in the combustion chamber.

Already checked in MSF but no one is having this under these specific conditions:

- Only on 3rd/4th/5th gear @ WOT
- During night time under 65 F outside
- Injecting Snow performance Water/meth "Boost juice"
- Tuned for a GTX3076r at 23 PSI
- Fully bolted on stock block

So my theory is that low temperature is messing up with the combustion while also getting methanol injected.
I noticed this since a couple of weeks ago, but last night I floored the gas on 3rd gear and heard the noises more frequently and got the P0300 (Random misfires in all 4 cylinders).

Any thoughts?

Last time spark plugs changed\regapped?
Last time MAF sensor cleaned?
AFR wonky at all under normal cruising?

Just answered that on the FB page lol. But let me paste the answers here just for future reference:

Changed spark plugs about 1 or 2 months ago. (NGK)
MAF Sensor cleaned also that same day and fixed a problem with one of the MAF sensor cables in the connector.
AFR looks good on WOT, but haven't checked under normal cruising.

Also additional info:

Noticed that the car stopped doing the misfires after a long drive, so it means that it gets to fully regular cruising temperature, so that supports my theory on BATs and external temperature affecting somehow the combustion.

does the CEL flash at you during the backfire/popping?


wouldn't hurt to check the plugs and maybe stretch the springs on the coil packs


p0300 could be from many different things though. im still dealing with mine lol..best of luck! curious to see what cures it

@ganque;

No flashing, just stays like that. Cleared it today at the morning. I'll check the plugs after work and take pics.

Is your meth controller using the maf signal, or boost reference? I have mine set up using a maf signal, and sometimes in part throttle tip in my meth starts spraying, because of the maf voltage set point. I have once triggered a misfire code and it was right after one of these part throttle events. I chalked it up to the plugs getting wet with meth, and then burning off seconds later.


How often is it occurring? How soon after clearing the code does it re-appear?

Boost reference.
It's a Labonte kit with a Failsafe module included.
Set to start spraying at 5psi and max injection @ 15psi

I got the code for the first time last night but I've sense this popping sound since a couple of weeks ago (since nights started to get colder).
The CEL never went away on my way back home, today I just cleared it with the AP.

Do you have a pump gas (no meth) map you can safely run?
I would try turning the meth off for a few days, and see if the issue is still present.

Actually just did this last night.
And you are completely right.

Meth + Cold Weather fucks up the combustion.

Now that we know the root cause, I'm not sure how to address it so I can still use meth for a night cruise for any chances of running into a red light with a v8 right next to me ;)

Maybe my car is injecting too much methanol? As I said I'm used the Snow Performance "Boost Juice" pre-mix on a D07 nozzle with a Labonte progressive kit with failsafe.

I've been noticing that my fuel trims go crazy when the car hasn't reached the full heat cycle in the thermostat. Is this normal?
And another interesting and odd fact is that my w/m injection gauge has been going crazy for the last weeks but I already checked and it's not injecting any meth, it just goes up without any reason.

Interesting.

I am also using the snow 50/50 juice but with a D10 nozzle, so you can't be injecting TOO much. We have been right around freezing temps here in NY, so I don't think that should pose an issue either. I've been running my meth kit for 3 years (year round), without issues.

I would try flashing your pump gas (no meth) map and drive that around for a few hundred miles. Then see if your trims are still acting up. If they are, you may either need a mafcal or just have a leak pre/post turbo.

Where in ny are ya?

I'm on LI.