NEED HELP! Another Rough Idle Thread

MotorenWerkeN52 · 07-23-2018, 10:06 PM

Hello All,

Having a bit of an issue with my car lately and can't seem to figure it out. Looking for some input.

The rpms on my car keep moving between 400 and 900 while at idle. When the rpm drops down to 400 it feels like the car is about to stall but the rpms come back up. This doesn't happen all the time and seems to go away if I turn the AC on. I have noticed when I first come to a stop the rpm stable but starts to fluctuate after a few seconds I recently replaced my spark plugs which solved the problem for about 2 weeks. Now it's back and even worse...

I had Delphi coils replaced about 50k miles ago
had the eccentric shaft sensor replaced 10k miles ago
All four new O2 sensors 2k miles ago
Spark plugs 1k miles ago

Current mods are AA tune, 3SIM and super Sprint headers. Currently at 98k miles

I ran codes using the Carly app and the car doesn't have any codes

Any input is much appreciated

R.Thillman · 07-24-2018, 03:40 AM

Seems like either bad pcv or vanos solenoids. when you come to a stop and idle is when the engine has the most vacuum pressure might hear a whistle noise. Try and opening you oil cap while your engine running and there should be no pressure at all holding it shut. Lastly maybe premature work cam ring seals. Not an expert but my that's my 2 cents hope you figure everything out!

MotorenWerkeN52 · 08-06-2018, 06:24 PM

Figured it out... Turns out the oil from my k&n filter got onto my MAF sensor. Cleaned there sensor and replaced oem filter, all good now.

07-23-2018, 10:06 PM	#1
MotorenWerkeN52 Second Lieutenant 198 Rep 285 Posts Drives: 2021 X3 M40i (Phytonic Blue) Join Date: Aug 2011 Location: Stamford, CT iTrader: (1)	NEED HELP! Another Rough Idle Thread Hello All, Having a bit of an issue with my car lately and can't seem to figure it out. Looking for some input. The rpms on my car keep moving between 400 and 900 while at idle. When the rpm drops down to 400 it feels like the car is about to stall but the rpms come back up. This doesn't happen all the time and seems to go away if I turn the AC on. I have noticed when I first come to a stop the rpm stable but starts to fluctuate after a few seconds I recently replaced my spark plugs which solved the problem for about 2 weeks. Now it's back and even worse... I had Delphi coils replaced about 50k miles ago had the eccentric shaft sensor replaced 10k miles ago All four new O2 sensors 2k miles ago Spark plugs 1k miles ago Current mods are AA tune, 3SIM and super Sprint headers. Currently at 98k miles I ran codes using the Carly app and the car doesn't have any codes Any input is much appreciated __________________ Current: 2021 BMW X3 M40i (Phytonic Blue) Sold: 2017 BMW X3 28i (Deep Sea Blue) \| 2011 BMW 328i E90 (LeMans Blue) \| 2007 Saab 9-3 2.0T (Silver Metallic) \| 2005 Scion tC (Indigo Ink Pearl)
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07-24-2018, 03:40 AM	#2
R.Thillman Enlisted Member 14 Rep 36 Posts Drives: 2007 e92 328i Join Date: Nov 2017 Location: Orange County iTrader: (0)	Seems like either bad pcv or vanos solenoids. when you come to a stop and idle is when the engine has the most vacuum pressure might hear a whistle noise. Try and opening you oil cap while your engine running and there should be no pressure at all holding it shut. Lastly maybe premature work cam ring seals. Not an expert but my that's my 2 cents hope you figure everything out!
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08-06-2018, 06:24 PM	#3
MotorenWerkeN52 Second Lieutenant 198 Rep 285 Posts Drives: 2021 X3 M40i (Phytonic Blue) Join Date: Aug 2011 Location: Stamford, CT iTrader: (1)	Figured it out... Turns out the oil from my k&n filter got onto my MAF sensor. Cleaned there sensor and replaced oem filter, all good now.
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