Bogging power issue M54 3.0i

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Wookster78

Member
Hi guys, got an issue on my 3.0i m54 E85 in that around 3.5k rpm the power seems to dip and rev lags then picks up again, power in 1st seems low but otherwise no noises, idling well and generally running fine. I have changed the Vanos seals around 4k miles ago and sorted the disa valve with upgraded flaps. I have also changed the coil packs and spark plugs. I originally thought it could be the vanos or solenoids as I have not cleaned the solenoids but at the time had no issues so was changing the vanos seals as a preventative maintenance job, any ideas what it could be, don’t want to start stripping components and going over stuff I have done previously if anyone has a better ideas, camshaft sensor maybe?

Thanks
 
Have you checked for codes?
Look for air leaks, especially the inlet elbow top pipe.

I had a problem with one vanos overhaul I did, where the shuttle valves that the solenoids open and close were sticking slightly in their bores, due to years of 'varnish' build up. I took the valves out and gave them a light rub with fine wet'n'dry. I found this by finding a code that said 'cam adjustment sticking' then seeing on live data on my Autophix that the cam angles weren't changing.
 
Hi, yeah I was going to mention no fault codes at all but when I did the rebuild I didn’t do the anti rattle or bearings, just did the seals and didn’t really check the functioning of the seats. Was thinking to just buy a full rebuild kit and a second hand vanos and rebuild then replace a complete unit. I replaced all the air intake hoses to the vanos so definitely not an air leak as I know they get brittle after a while. Just didn’t want to spend on a new kit and secondhand unit if it could possibly be something else but does sound like it could be poorly functioning vanos
 
Sorry was thinking of the oil return pipes, just checked the air inlet manifold hoses and all fine, think it worth another refurb on the vanos and solenoids?
 
Wookster78 said:
Sorry was thinking of the oil return pipes, just checked the air inlet manifold hoses and all fine, think it worth another refurb on the vanos and solenoids?
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Thats a lot of expense and unless you can hear it rattling I doubt very much that the extra bits will make the difference.
I would definitely try cleaning out those shuttle valves first.
Also try to get some live data to see if the cam angles do change when you rev the engine.
 
Ok, not sure I can get the solenoid valves off though without removing the vanos, top one looks ok but not sure I can get to the bottom one. Will Carly or BimmerCode give me live data?
 
Wookster78 said:
Ok, not sure I can get the solenoid valves off though without removing the vanos, top one looks ok but not sure I can get to the bottom one. Will Carly or BimmerCode give me live data?
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I'm not sure, never used them. Autophix did it for me.
 
Ok, will see if it has the features. What’s the best way to clean the solenoids and get the shuttle out as the early ones look like it’s all inside the body unlike the later solenoids on the N52 engine?
 
The solenoid unscrews, then the valve just sits inside the housing. You can draw it out with a magnet if needed. There is a spring at the far end of it, so don't lose that.
Of course gravity will be more your enemy than your friend for the lower one.
 
We shouldn't get too blinkered on this yet though.
Camshaft position sensors?
Even remotely possible it's a MAF problem.

Have you tried resetting the vanos adaptations to see it that makes a difference?
Or disconnecting the MAF so it runs on the DME's default map?
 
Nope not tried that yet, took the MAF off though and looked really clean but could be faulty, where are the camshaft sensors, do I need to take off the rocker cover to access them? Assume if they are cheap and easily accessed could replace anyway
 
Top one came off easy enough but can’t seem to get the little pin out even with a magnet, any other tips, seems pretty stuck and gunky in there ?
 
Wookster78 said:
Top one came off easy enough but can’t seem to get the little pin out even with a magnet, any other tips, seems pretty stuck and gunky in there ?
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Try a little squirt of plusgas or wd40, then push it in against the spring. Nothing much to get hold of I know, but a twist can help too.
Should be free to move so it sounds like we've found one issue at least.
 
I can get to move freely but even with pliars it’s not coming out, should it pop up as it just sits flush until you turn the solenoid upside down and it then drops freely?
 
Wookster78 said:
Ah ok the spring inside the housing of the vanos moves fine it was the pin in the solenoid that was a bit stuck
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You do have the valve there between the spring and the solenoid?
 
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