[Nandohatesyou]

As the title states, I've been having a weird idle for the past week and haven't been able to figure it out or pinpoint where the problem lies. I wouldn't exactly call it rough, but it definitely sounds almost like a misfire.

Mods are carbon fiber intake, Dorch HPFP, chargepipe, intercooler, cat-less downpipe.

Around the same time this whole issue started, I was driving home late and I hit a nasty pothole. I knocked my intake filter off my car. Pulled over, reattached the filter, and drove home. The next morning, I went to check to see if I had a bent rim and nothing, so I started the car up and the strange idle was still present. I've so far replaced the MAF sensor and checked my intake (Turner Motorsports CF) for any cracks and I couldn't see any issue; also unflashed to Stock, still present and reflashed to Stage 2 ACN tune, still present. Any thoughts? My mechanic want's to perform a boost leak test and I'm leaning towards it could be spark plug related, any other input? I'll attach a log of the idle and a log of doing a pull, plus a small audio clip off the exhaust which shows off the idle very nicely.

https://www.bootmod3.net/log?id=61f8...0b4367c325f1cb - Idle Log

https://www.bootmod3.net/log?id=61f9...0b4367c325f892 - Pull

View post on imgur.com

[Nandohatesyou]

Well.. changed out the coil packs, checked spark plugs, changed fuel, checked for codes, changed the MAF and still nothing. Still has the same strange idling noise and it's strange that this issue just popped up out of the blue.. any advice and what to look towards next?

[Anonymoose]

Originally Posted by Nandohatesyou

Well.. changed out the coil packs, checked spark plugs, changed fuel, checked for codes, changed the MAF and still nothing. Still has the same strange idling noise and it's strange that this issue just popped up out of the blue.. any advice and what to look towards next?

Check the chargepipe for any leaks.

[Nandohatesyou]

Originally Posted by Anonymoose

Check the chargepipe for any leaks.

Thank you, just dropped it off at my mechanics and told them to check the intercooler connections, chargepipe, downpipe, you name it.

[MONSTAR]

I know you said you changed the spark plugs but that definitely sounds like a misfire. I just went through this 6 months ago where I had that issue after a 1st, 2nd pull through redline in each gear. I got the spark plugs replaced and about 3 weeks later I did another intense pull and got the same sound AGAIN. This actually happened to me twice after replacing the spark plugs. Each time, it was found that the ceramic portion on one plug had cracked. My shop was just replacing single plugs until the last time they finally gave me an entire new set and its been good since.

You may have received a bad batch of plugs. The hairline cracks can be so minuscule that you can't see them and wouldn't know that they were bad during an install. Then after driving the vibrations can further crack them.

EDIT: If you've ever ordered plugs yourself you will note that the boxes they come in are super thin and offer basically no drop protection.

Good luck, I hope you find the issue. Please give us updates when you do.

[Nandohatesyou]

Originally Posted by MONSTAR

I know you said you changed the spark plugs but that definitely sounds like a misfire. I just went through this 6 months ago where I had that issue after a 1st, 2nd pull through redline in each gear. I got the spark plugs replaced and about 3 weeks later I did another intense pull and got the same sound AGAIN. This actually happened to me twice after replacing the spark plugs. Each time, it was found that the ceramic portion on one plug had cracked. My shop was just replacing single plugs until the last time they finally gave me an entire new set and its been good since.

You may have received a bad batch of plugs. The hairline cracks can be so minuscule that you can't see them and wouldn't know that they were bad during an install. Then after driving the vibrations can further crack them.

EDIT: If you've ever ordered plugs yourself you will note that the boxes they come in are super thin and offer basically no drop protection.

Good luck, I hope you find the issue. Please give us updates when you do.

Well.. guess what the shop just found

The shop I took it to, who's not my usual go to mechanic by the way, found a crack in spark plug number 5 causing a misfire, but it wouldn't throw a code. Bear in mind, I just took my car to my buddies shop yesterday and told him I suspected it was a spark plug and he said he looked at the spark plugs and that they were fine. I still payed my buddy 100 bucks for a boost leak test and replacing my coil packs. I'm a little pissed, considering I just shelled out 570 for new spark plugs plus labor (fixed my downpipe banging on something). Really hope this is the end of my problems and I will update the thread when I pick up my car later today. Moral of the story: don't go to your friends shops just because they are your friends.

[Nandohatesyou]

Update, cracked spark plug #5, replaced all with OEM BMW Bosch and the problem is now gone!

[MONSTAR]

Yeah forgot to mention that mine didnt throw any codes either!

Glad you got it fixed bud