Loss of power above 7600rpms

[Matty088]

I’ve noticed the car loses some power above 7500-7600rpms. I wouldn’t call it a hesitation or a misfire. It just falls on its face a bit as it approaches redline. You can feel the momentum slows down. It’s not a jerky feeling. It’s smooth. You’d think it’s a boost leak if the car was turbo.

could this be vanos related? The car has 78k and there hasn’t been a vanos Recalibration. Spark plugs are new.

[mrgizmo04]

Usually the flattening, or even a drop in power in higher rpm, is VANOS related. Suggest doing the full job, replacing the seals, etc.

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[8 Coupe]

It's worth reading the VANOS overhall procedures on Beisan's website.

http://www.beisansystems.com/procedu..._procedure.htm

[eacmen]

+1 for VANOS.


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[JamesSJ1]

+1, and also timing. VANOS is all about the engine being able to vary timing, and if it's off enough, the adjustment range will be too limited. My timing was off just enough that it would barely pass the test, but power faded out >7k rpm. Everything else was normal. Got the timing fixed up and the power band was much better again all the way to redline.

[eacmen]

+1, and also timing. VANOS is all about the engine being able to vary timing, and if it's off enough, the adjustment range will be too limited. My timing was off just enough that it would barely pass the test, but power faded out >7k rpm. Everything else was normal. Got the timing fixed up and the power band was much better again all the way to redline.

Agreed. Assuming there was no major top end work before the loss of power then the timing likely hasnt drifted.

Search around. There are losts of guides/threads out there but basically you should be thinking about doing
- upper timing chain guide
- exhaust hub (if tabs broken) and/or drilled oil pump disc
- S65 diaphram springs to reduce rattle
- uodated torx cam bolts
- VANOS rebuild - do it yourself or buy one remanufactured one
- solenoid pack

Good luck!


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[Matty088]

How does vanos relate to a valve adjustment?

a “valve adjustment” was suppose to be performed at inspection 2. I’ve done everything else. Is this timing related ?

how could I test the vanos? Would it throw codes ?

[Matty088]

Oh and I have no rattle or anything. Engine runs as smooth as silk. It’s just way up by the redline there is a loss of power.

[eacmen]

How does vanos relate to a valve adjustment?

a “valve adjustment” was suppose to be performed at inspection 2. I’ve done everything else. Is this timing related ?

how could I test the vanos? Would it throw codes ?

1. Valve adjustment has no affect on timing or VANOS.
2. VANOS doesn't throw codes until it is *way* out of spec. Same with timing, timing has to be way off before a code is thrown.
3. You can test the VANOS with a pressure tester (https://nam3forum.com/forums/forum/m...pressure-tests)
4. You can also test the VANOS with DIS (https://forums.m3cutters.co.uk/threa...ng-dis.106289/)

At the car's age and milage the VANOS (and related parts mentioned above) will have to be done at some point. Same with rod bearings. If you plan on keeping the car long term I would start planning/budgeting on doing both.

[Matty088]

Thanks for the answer. I’ll start reading up on it.

[sapote]

How does vanos relate to a valve adjustment?

vanos performs automatic valve timing adjustment, not the valve clearance.

[Icecream]

I’ve noticed the car loses some power above 7500-7600rpms. I wouldn’t call it a hesitation or a misfire. It just falls on its face a bit as it approaches redline. You can feel the momentum slows down. It’s not a jerky feeling. It’s smooth. You’d think it’s a boost leak if the car was turbo.

could this be vanos related? The car has 78k and there hasn’t been a vanos Recalibration. Spark plugs are new.

I can't imagine a vanos issue would only surface at those RPM's. Maybe timing is being pulled for some reason (detonation, bad sensor or something). Has this been consistent through more than one tank of gas? Post a video if you can.

[Matty088]

Indont think it’s the vanos. I read a lot about it. My vanos doesn’t make noise. And from what I read vanos issues effect low end torque more so than the upper Rpms. This is like the last couple hundred rpms. It just feels like it loses its umphhh. Nothing jarring about it. No noise. It almost feels like I am beyond redline and it’s out of juice. But I am not. It pulls very strongly and very cleanly until this point.

i made an appointment to have valves calibrated. The car is approaching 80k miles and to
my knowledge hasn’t been done. It’s being done next Saturday. My buddy is Bmw tech for 20 years and runs a garage out of his house. Maybe it’s this. We shall see.

[eacmen]

Indont think it’s the vanos. I read a lot about it. My vanos doesn’t make noise. And from what I read vanos issues effect low end torque more so than the upper Rpms. This is like the last couple hundred rpms. It just feels like it loses its umphhh. Nothing jarring about it. No noise. It almost feels like I am beyond redline and it’s out of juice. But I am not. It pulls very strongly and very cleanly until this point.

i made an appointment to have valves calibrated. The car is approaching 80k miles and to
my knowledge hasn’t been done. It’s being done next Saturday. My buddy is Bmw tech for 20 years and runs a garage out of his house. Maybe it’s this. We shall see.

You mean a valve adjustment? I don't know what a valve calibration is.


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[eacmen]