[Anotherlongshot]

E90 N52 Low rpm miss. Already changed 6 coils and plugs, removed cleaned and installed Vanos and changed the oil and filter. No fault codes registered on inpa but still high gear low rpm miss that I can feel when driving. Any suggestions? Thanks.

[Bimmer Pleaser]

Vacuum leak maybe?

[mike sevel]

When was the last time you cleaned your MAF sensor and throttle body?
DIY's are available for both but be sure to use the correct cleaner for each.
Mikey

[Anotherlongshot]

It's been a while. I will do both next. Would either of those issues give a fault code on inpa? Thanks.

[BimmerNugget]

Clean the MAF sensor and try again.

[Anotherlongshot]

Will do. Thanks.

[mweisdorfer]

Originally Posted by Anotherlongshot

E90 N52 Low rpm miss. Already changed 6 coils and plugs, removed cleaned and installed Vanos and changed the oil and filter. No fault codes registered on inpa but still high gear low rpm miss that I can feel when driving. Any suggestions? Thanks.

What is the status of your air filter?

Vanos would just give you a half engine light. It's caused from the 15,000 mile oil intervals. The Vanos gets gummed up as a result. To try and avoid this problem and still use 15,000 oil intervals you can change the filter out at around 7500 miles and do an oil flush before you change the oil every time, or change the oil and do the oil flush day every 8 to 10,000 miles. You should also pull, clean and switch the Vanos once a year.

I agree with the above posters about your MAF. Clean it with CRC MAF sensor cleaner. If you are using an oiled filter like a K & N or AFE, often times the oil from these filters can gum up the MAF. To avoid this problem, clean your MAF once a year and try not to over oil your filter when you clean and re-oil it.

Last, use a fuel injector cleaner like redline or 20 gallon formula Techtron (2x) a year.

[BashShah]

Originally Posted by mweisdorfer

What is the status of your air filter?

Vanos would just give you a half engine light. It's caused from the 15,000 mile oil intervals. The Vanos gets gummed up as a result. To try and avoid this problem and still use 15,000 oil intervals you can change the filter out at around 7500 miles and do an oil flush before you change the oil every time, or change the oil and do the oil flush day every 8 to 10,000 miles. You should also pull, clean and switch the Vanos once a year.

I agree with the above posters about your MAF. Clean it with CRC MAF sensor cleaner. If you are using an oiled filter like a K & N or AFE, often times the oil from these filters can gum up the MAF. To avoid this problem, clean your MAF once a year and try not to over oil your filter when you clean and re-oil it.

Last, use a fuel injector cleaner like redline or 20 gallon formula Techtron (2x) a year.

1+

I would hit fuel Injector cleaner first.
go to Chevron on your next NEARLY Empty Tank.
fill up with their Best.
Chevron with Techron is exactly what's in the bottle that BMW sells.

might recommend 2 tanks fills back to back.

[Anotherlongshot]

Thanks for the replies. Air filter was changed along with the above mentioned maintenance. I will clean the MAF with the recommended cleaner. I will also use injector cleaner and use Chevron best gasoline. I will report back. Thanks again.

[nsjames]

if you go into the rough running in INPA, is it always one specific cylinder or is it across them all?

and check the injector harness. The plugs at the injectors loosen up and you need to tension the terminals. That's what my miss was, just a loose connection.

[Anotherlongshot]

I'll check that too. Thanks for the reply.

[e90yyc]

I've always been curious why some seem to have issues with clogged Vanos, as my experience couldn't be more different.

Mine have 280,000 kms (180,000 miles) on them, have never been cleaned, and car observes standard once-a-year or 20,000 km oil change interval. They came out looking just about perfect.

Good luck man. I'm sure you'll get to the bottom of this!

[nsjames]

Originally Posted by e90yyc

I've always been curious why some seem to have issues with clogged Vanos, as my experience couldn't be more different.

Mine have 280,000 kms (180,000 miles) on them, have never been cleaned, and car observes standard once-a-year or 20,000 km oil change interval. They came out looking just about perfect.

Good luck man. I'm sure you'll get to the bottom of this!

20K km is what like 12K miles? You're still ahead of the oil change minder.

also a big issue is people taking them to the local valvoline or whatever and using conventional oil with extended OCI.

I've seen motors that look like the top end is packed with chocolate fudge.

[Anotherlongshot]

I didn't like the looks of my oil after the last change so I decided to clean the Vanos. I didn't think they were bad but it was worth the effort. It's not difficult to do.

[e90yyc]

Originally Posted by nsjames

20K km is what like 12K miles? You're still ahead of the oil change minder.

also a big issue is people taking them to the local valvoline or whatever and using conventional oil with extended OCI.

I've seen motors that look like the top end is packed with chocolate fudge.

I struggle to think a 3k mile difference would result in a night-and-day difference, but I can appreciate that. My car has been dealer-serviced for most of its life so it has always lived on BMW-prescribed oil, so perhaps that is why, as you say.

I can't believe the OCI from the factory is 24,000 kms or two years... Two years! I've looked at the service records and it appears the PO was smart enough to do it annually though, thank god...

Edit: PO was also a highhhhh mileage driver, so while he may have changed it annually, it might actually have been done at closer to the 24,000 km interval. Not 100% sure on that.

[EnintyToo]

Long OCIs do not clog up and damage the VANOS solenoids. I ran 17,000-mile OCI up to 221,000 miles I cleaned the VANOS every 50,000 miles and that was starting after 150,000.

Anyway, a seasoned BMW tech taught me a trick for non-code drivability issues. Unplug the MAF and drive the car for a bit and let the built-in engine mapping run the engine for 10-15 miles. Replug the MAF and clear the code.

[Anotherlongshot]

That's interesting. Can you elaborate?

[Anotherlongshot]

Cleaned MAF and that helped. Still a miss, especially when coming to a stop light or sign - the car seems to stumble a bit and recover. Found a bottle of BMW fuel system cleaner in my trunk and added it. Also purchased a bottle of Techron, but will wait a while before adding it. We'll see what effect that has on the situation. Thanks for the replies. Any others are appreciated.