M52 - I think I'm having vanos issues

[ascendotuum]

I have a 1987 BMW 325is - but the car has a motor and transmission swap. The engine is a 1997 M52b28 and ZF 5-speed transmission from a 1997 328is.

Here's my problem. I'm having serious hesitation issues and a hunting idle. The hesitation occurs only under heavier acceleration (around 60% throttle or more) at low rpms (around 1500rpms to 3000rpms) and again at higher rpms (around 5000rpms up to redline). If I'm light on the throttle it doesn't hesitate at all. Also when its cold, and sometimes even after it's warmed up, it will not idle smoothly. The rpms fluctuate from about 600rpm up to 1000rpm back and forth.

I'm reading that these symptoms are tell-tale signs of a vanos unit that is malfunctioning. Does this sound familiar to anyone? At first I thought maybe it was my fuel pump or fuel filter going bad, but if that were the case then the mid-range rpms would have the same problem right? The fact that it's occurring at low, fine in the midrange, then again at high rpms leads me to believe it's not a fuel issue?

I think I'm going to buy the Dr. Vanos stage 1 single vanos kit. What else do I need to buy? Valve cover gasket, seals, cam blocks, locking pin, etc... ?

Thanks

[Wanganstyle]

Sounds like a vacuum leak. You can see if the vanos is causing weird issues by unplugging it and driving to see

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[ascendotuum]

I will try that. But how would I go about tracking down a vacuum leak?

[dude8383]

I will try that. But how would I go about tracking down a vacuum leak?

Smoke test/machine is your best bet :up:

[ascendotuum]

Thanks. And to test the vanos I just unplug the solenoid correct?

Thanks

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[agent]

Rebuilding the vanos yourself using the Biesan kit is about 25% the cost of the Dr. Vanos unit.

[Wanganstyle]

Thanks. And to test the vanos I just unplug the solenoid correct?

Thanks

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using simple logic this would make perfect sense.........and was already suggested to you above.


If you don't really know how the vanos works or how its activated; its doubtful you can diagnose it correctly.

[ascendotuum]

I'm just going to ignore the condescending tone here. I just wanted to make sure.

Thanks for your help guys.

[e30rapidic]

I'm just going to ignore the condescending tone here.

good for you!

Unplug it and drive around like others have said. If you do need to rebuild the VANOS, beisian is the way to go. Excellent tutorials on his webpage and the prices can't be beat. I've used them.

It helps to have the cam timing tools but I've done it numerous times without them.

[ParsedOut]

+2 on a vacuum leak.

Occam's razor my friend, start with the most likely issues and work up from there. Vacuum leak is the most common cause for drive ability issues.

[ascendotuum]

So before I left work today I unplugged the vanos solenoid. As I suspected, the hesitation and idle issues disappeared. Halfway home I plugged it back in and the hesitation started again.

I still want to verify that I don't have any vacuum leaks but I don't know exactly where to start, so I will have my mechanic friend help me with that.

But it sounds like I need the beisian kit.

[ParsedOut]

So before I left work today I unplugged the vanos solenoid. As I suspected, the hesitation and idle issues disappeared. Halfway home I plugged it back in and the hesitation started again.

I still want to verify that I don't have any vacuum leaks but I don't know exactly where to start, so I will have my mechanic friend help me with that.

But it sounds like I need the beisian kit.

Ahhh, VANOs sucks. Easiest way to check for vacuum leaks is to use carb cleaner, there are a few good videos on Youtube to guide you through it.

[franky2fingaz]

good for you!



It helps to have the cam timing tools but I've done it numerous times without them.

How? Plate bolted down method?

OP: Rent the tools, get the rebuild kit, watch some great youtube videos, don't get high, stay organized and dive right in.. no biggie

[Nats88M3]

Where at in MD ? I've got the cam lock tools water pump wrench and fly wheel lock pin!! 12 pack to let you use it! I'm in Fairfax

[Nats88M3]

Oh by the way take out the solenoid and clean the piston it could be getting stuck also.... my e36 M3 was doing the same and it helped but I got a rebuilt kit from Dr vanos just because I could hear that it was starting to rattle.