N52 with 130k miles down on power, no codes

FTP20 · 11-26-2022, 07:49 PM

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?

PhaceN52 · 11-28-2022, 02:13 AM

Try this

https://www.e90post.com/forums/showthread.php?t=1304563

sabino56 · 11-28-2022, 10:51 AM

Just curious, what’s basis of why you think it’s 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. There’s 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.

Suvorovo · 11-28-2022, 11:43 AM

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.

11-26-2022, 07:49 PM	#1
FTP20 Private 34 Rep 87 Posts Drives: Four door ///M Join Date: Nov 2018 Location: North iTrader: (0)	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
PhaceN52 Private First Class 178 Rep 196 Posts Drives: '06 E90 N52B30 US spec Join Date: Mar 2016 Location: Italy, Dolomites iTrader: (0)	Try this https://www.e90post.com/forums/showthread.php?t=1304563
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11-28-2022, 10:51 AM	#3
sabino56 Private First Class 90 Rep 154 Posts Drives: 2006 E90 330i Join Date: Mar 2018 Location: AZ, Tucson iTrader: (0)	Just curious, what’s basis of why you think it’s 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. There’s 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
Suvorovo Lieutenant 281 Rep 524 Posts Drives: Creaky e90 330xi 6MT Join Date: Feb 2022 Location: New Jersey iTrader: (0)	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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