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Discussion Starter #1 (Edited by Moderator)
Hi all

My S85 is causing me headaches.

It's really down on power at low revs and the power button makes next to no difference. Its dead below 6500/7000 rpm.

Only fault showing is a bank 2 O2 sensor heating circuit.

It feels like it's massively pulling the timing.

If you floor the throttle below 3k you feel it go then pull back/hesitates. It's feels ok on 1/2 throttle.

With dsc off, rolling in 1st gear @ 3k rpm on a wet road i can't provoke wheel spin!!!

I thought maybe MAF's so drove with them disconnected. It's worse.

Car is completely stock.

I'm wondering if it's VANOS related. Any ideas????

I've got inpa (It's all in German though) can I test the VANOS with inpa??

Thanks
 

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Bimmer logger is not expensive

you can log fuel pressure , timing , vanos angle requested, vanos angle actual and a dozen plus useful parameters.

gives a good start for chasing pure mechanical issues that do not result in codes
 

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I'm going lean towards O2 sensor. The heater has to be working properly for it to read lambda correctly. The DME uses lambda to adjust fuel trim. Odds are it's adjusting the mixture improperly as a result.
Disconnecting MAFs, the engine goes into limp mode as the alphaN tables are set for a conservative, safe value.
 

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Bimmer logger is not expensive

you can log fuel pressure , timing , vanos angle requested, vanos angle actual and a dozen plus useful parameters.

gives a good start for chasing pure mechanical issues that do not result in codes
BImmerlogger doesn't work with the E60 DMEs yet, IIRC.
 

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Discussion Starter #5
I'm going lean towards O2 sensor. The heater has to be working properly for it to read lambda correctly. The DME uses lambda to adjust fuel trim. Odds are it's adjusting the mixture improperly as a result.
Disconnecting MAFs, the engine goes into limp mode as the alphaN tables are set for a conservative, safe value.


Thanks Mr C.

I'll get the lambda changed as it's throwing a fault. It's just so down on power it feels more than that.

It's had the internal VANOS pipe replaced when did the rod bearings so I know that's ok. Is there a chance the pump is failing? Or that one of the cams has stuck in the retarded position?
 

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Discussion Starter #6
Well it looks like my phone app was miss-interpreting the fault. Plugged inpa in and it's a failing camshaft sensor. Which make far more sense.
 

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I had failing camshaft sensors on my previous M5. The car drove like an new car when I replaced them. How the hell do these things deteriorate? They are simple Hall sensors. Is it the temperature or so they run too much current through these things to get sufficient voltage response. Amazing.
 
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