Rough idle on cold start

[trevor617]

So started having this issue recently where when I start the car on a cold engine, it will struggle to idle and dip down and be very rough for about 20-30 seconds then even out and be fine. Has even died once or twice now. After that, car is completely fine and runs completely fine with no issues at all while driving. And if I go to start it again when the engine is warm, I don’t have the issue, only on cold start.

I have tried a couple things, one is gone back to stock tune as I am bm3 stage 2. That didn’t change anything. Second is I have reset adaptions on the car and that fixed it for the first initial start up after I do the reset, then the problem is back on the next cold start. I’m kind of confused and just seeing if anyone can point me in a direction on things to check?

Also one last thing, it has thrown some codes 2 time while it was happening, other times it doesn’t throw codes, seems to throw them when it is really rough. I will attach the codes

[Pewtinn]

First guess is replace the spark plugs (with proper gapping).

Second, do you have aftermarket intakes? I've heard some cheaper ones can contribute to a weird idle. Clean the MAF Sensors w a MAF cleaner.

[blu_m3cs]

are you on E?

nevermind just reread the post lol

[trevor617]

Just wanted to updated, I do have front mount intakes from agency power, the problem ended up being a MAP sensor, specifically the one behind the oil cooler, little harder to see and get too. But that was bad and just throwing off everything. When I took it out it had some oil/gunk onl it from not having a catch can so ordering one of those asap to prevent further problems. Got it replaced and haven’t had a problem sense. On cold starts still have a tiny bit of a rough idle but from what I’ve learned that’s just normal with front mount intakes. Hoping to get a custom tune at some point to take care of that

[MantasB]

Originally Posted by trevor617

Just wanted to updated, I do have front mount intakes from agency power, the problem ended up being a MAP sensor, specifically the one behind the oil cooler, little harder to see and get too. But that was bad and just throwing off everything. When I took it out it had some oil/gunk onl it from not having a catch can so ordering one of those asap to prevent further problems. Got it replaced and haven’t had a problem sense. On cold starts still have a tiny bit of a rough idle but from what I’ve learned that’s just normal with front mount intakes. Hoping to get a custom tune at some point to take care of that

I am having the same exact issue that you are describing and trying to figure out what is causing this... Is the sensor you are referring to shown in the attached diagram? Or is there another one behind the oil cooler?

[trevor617]

Originally Posted by MantasB

I am having the same exact issue that you are describing and trying to figure out what is causing this... Is the sensor you are referring to shown in the attached diagram? Or is there another one behind the oil cooler?

Number 2, the map sensor was what ended up being my problem. Give that one a check. It may not look like it is broke but maybe try to clean it off with some crc maf cleaner or put in a new one if able to

[trevor617]

Originally Posted by trevor617

Number 2, the map sensor was what ended up being my problem. Give that one a check. It may not look like it is broke but maybe try to clean it off with some crc maf cleaner or put in a new one if able to

Here is a picture of the bad sensor