N52B30 rough running 2500-3000 rpm medium load

J

Joël D.

Member
Hi guys,

I have a problem with my '08 3.0 si and it is driving me crazy. During medium acceleration, around 2500-3000 rpm the engine accelerates quite rough (difficult to discribe). No power loss, no error codes. At first I thought it was a misfire, so I bought new coils, but that didn't solve the problem. Now I am suspecting the VANOS, since it only happens during a certain load cycle, not at idle for instance.

The car has no power loss, it runs fine, but it is just annoying...

[youtube]https://youtube.com/shorts/6kpHxS6lfd8[/youtube]

You can hear it (slightly....) at 17 seconds and when I say now at the end....

I also noticed that the variation in the inlet VANOS on idle was quite large, like 3 degrees, where as the outlet stays constant. Is that normal?
 
I just cleaned the solanoids. Both looked clean and worked fine. Decided to pop them back in again.

I changed the spark plugs yesterday, and this seemed to improve the situation quite a lot, although not all of it. Especially in the second gear, from 2-3k rpm there is some strange Rumble. Still, no loss of power, no fault codes. It is kinda acceptable for now, but in the end I would like to know the real issue...
 
Ok, I thought that the problem was smaller after cleaning the Solenoids, so decided to replace them.

However, no Bueno. Still some jittering around 2000-3000 rpm in the first 2 gears. Other gears are fine. Higher revs also. No power loss. Just annoying sound. It nearly sounds like rod knock, but then slightly less loud. :o

I think I'll bring it to the garage for diagnosis, I am lost.
 
Could it be the disa.think there are 2 on your car so might be worth checking whether they are knackered
 
I checked the big one. That was was tight as hell. I believe there is a second one under the air intake? Need to check how to access it
 
Joël D. said:
I checked the big one. That was was tight as hell. I believe there is a second one under the air intake? Need to check how to access it
Click to expand...
You can get it out in situ with the alternator off, some stretching, probably swearing and regular breaks.
You need replacement bolts if you take the alternator off.
 
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