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      11-26-2022, 07:49 PM   #1
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N52 with 130k miles down on power, no codes

I recently purchased an LCI N52 6spd manual with 130k miles and a good service history. It runs well and has no codes present but it feels down on power and less energetic than I think it should be. The only unusual behaviour is a bit of idle oscillation and roughness for the first ~10 seconds on cold start in cold weather.

I have compiled a list of possible culprits but would appreciate feedback on where to start.

Replace spark plugs and ignition coils
Test DISA operation (use ISTA ?)
Clean MAF
Clean VANOS solenoids
Clean or replace VANOS check valve oil screens in block
Check PCV operation + check for cracked hoses behind the head

Any tips or trick or have I missed anything?

Last edited by FTP20; 11-27-2022 at 10:43 AM.. Reason: 1
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      11-28-2022, 02:13 AM   #2
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Try this

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      11-28-2022, 10:51 AM   #3

Drives: 2006 E90 330i
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Just curious, whatís basis of why you think itís low on power? That is, have you had a lot of experience with this model or just think it should be faster?

Checking DISAs is a worthwhile effort on a new to you car of that age.
A bad DISA can cause degraded performance in a rpm range but I only noticed mine going bad as a change from the normal after owning the car many years. Not sure I would have noticed it on a new to me car as it ran smoothly even with bad DISA.

Original DISAs can drop a pin into intake if shaft breaks. There are threads on that on here somewhere.

INPA has a DISA check but not sure it can detect a broken flap. Thereís probably a discussion on that here somewhere.

If taking off to check, the outer one is relatively easy to get to. The inner can be removed without taking off intake if you remove the alternator. (Alternator bolts are one time use).

If nothing obvious like a loose flap you can plug them in and actuate them with INPA to check operation. If you do this after removing the alternator, remember it has a 12v connection you removed you have to protect/isolate before reconnecting the battery.
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      11-28-2022, 11:43 AM   #4
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DISA valves are currently on sale at FCP for $663. If you replace your flaps, just go with Genuine BMW for piece of mind. People had issues with OE flaps failing prematurely or insufficiently greased. PCV kit is also on sale for $349. Cleaning Vanos solenoids is only temporary, but you'd have codes/rough running/startup if the Vanos solenoids were getting stuck or failed.

Did you get a decent oil filter? Cheap chinese oil filters can collapse and cause issues although much greater than what you're experiencing.

You've pretty much checked all the boxes.
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      12-03-2022, 08:49 AM   #5
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Might be worth cleaning injectors too.
Just let your soul glo....
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