RedlineEveryday

Plugs are about 15k miles old, coils are BHR w/ 30k miles on them. When it's cold out I get a hesitation/misfire/sputter over 7,000rpm. It's fine when it's warm out though.... Ideas on what it could be? Just checked all my wires to make sure they're snug and none were loose.

Loki

iTrader: (1)

Check your fuel trims via OBD. Possible something is messing with your fuel and air delivery, and cold air males it just bas enough to misfire. What kind of cold and what kind of warm are we talking about?

RedlineEveryday

I'm in Kansas, so 2 days ago it was 75 degrees and this morning it got down to 18 degrees.

NotAPreppie

Presumably you're waiting for it to warm up before driving it hard...

Check your IAT. It's possible that the sensor (it's inside the MAF) is malfunctioning but only showing up at low temperatures.

RedlineEveryday

I have an S2 so it has the Rev limiter. I still wait another few minutes after it's "warm" to really rev it out. Would I check that with an OBD2 scanner?

NotAPreppie

Yah, you'll need a scanner. Elm327 bluetooth adapters are cheap and you can use an app on your phone.

RedlineEveryday

Grabbed a can of MAF sensor cleaner and a can of electrical contact cleaner. Gonna spray it down tomorrow and treat the plug to see if it helps. If not I'll have my buddy bring his scanner over this week some time. Really hoping it's nothing major, it's my only car and I don't graduate until May. She's at 56k miles and has been well taken care of so I'm hoping for the best!

NASTYjoe

I'm having this same issue. No problems when it is warm outside, but if it is under 32 degrees then it'll misfire around 8.5k rpms. It may just take the engine longer than usual to completely warm up. I just cleaned my MAF, hopefully thats the fix. Im moving down south soon, so im not too worried about it.
Brand new sparks/coils/plugs (BHR) 80k miles on the car.

Dave04

You should try to keep the RPMs under 5-6k until the temp gauge is just left of center. It's not recommended to redline rotary's or any engine for that matter until they reach operating temp.

If it only does it when cold, I wouldn't worry to much about it. There are numerous possibilities for the cause of a misfire. If you really want to dig into it, gather some engine data. Fuel trims, MAF, 02 sensor readings ect... Without these everything is just a shot in the dark....

David

NASTYjoe