ENGINE WON't GO ABOVE 1,000rpm! VANOS OIL PRESSURE? NEED SOME HELP.

I'm leaning towards a broken flywheel tooth as the initial problem to chase.

The waveform in the first image almost makes sense with the first two missing peaks. It's hard to say for sure, but that looks like the signal I would expect from the two missing teeth which provide the zero angle reference to the DME. But then, after a few more cycles, there is another dip that doesn't look like the first. A new flywheel has two non-installed teeth and the rest are continuous all the way around. Whatever that dip is, it doesn't seem to follow what one would expect to see unless there is another defect on the flywheel.

Secondly, the DME controls VANOS actuator positions based on the difference in *perceived* timing between the crank position sensor and the camshaft position sensors. The cam position sensors have a similar zero reference "gap" on the sensing wheels. Basically, it expects to see a particular time difference between seeing the crankshaft zero trigger and the camshaft zero triggers. This time delay when calculated against RPM, provides the DME the CAM lead/lag angle which is used as the "actual" VANOS actuator position you can read out in INPA.

So basically, the crankshaft position sensor becomes a "reference" for much of the MSS65 engine control.

If the CPS signal is corrupt, then all the calculations the DME makes for timing will be as well.

I would completely disregard all the VANOS control errors, the camshaft sensor errors and the potential bad PLCD you have on the SMG (the 510D and 510E) until the CPS error is sorted out.

There is one overarching possibility will this collection of error codes...how is your battery and alternator? Odd voltage fluctuations (i.e. rectifier failure) will wreak havoc on the car's electronics, so I would rule that out to start if you haven't.

You can check the flywheel without dropping the transmission if you have someone bar the engine over with a 32mm wrench on the crank while using a boroscope through the CPS hole to observe the flywheel.

Flywheel tooth damage is not uncommon on our cars and most often a result of a clutch disc failure resulting in a material retaining rivet which has broken the head off and it's been punted around in the bell housing for a while.

Excellent amount of starting information provided here though in the initial post, it certainly looks as if you have all the tools needed to get it sorted.

Edit: And not to discredit Bill by any means, but if your VANOS pressure is really low, it's a separate fix from the CPS. Since the DME controls the VANOS solenoids to move the actuators, personally I would straighten out the control system for VANOS before chasing the pressure problem. It may very well be that the DME is commanding the rest of the VANOS system to do something which is dumping all the pressure, i.e. odd solenoid position, overriding accumulator solenoid, etc.

And finally, be *very* cautious running the engine if VANOS pressure is really that low. There are two possibilities if the DME is not causing it. The first being a leaking discharge line internal to the engine, the second being far more nefarious...failing drive gear teeth. If that's the cause and the failure completes, your not driving the main oil pump anymore either.

THANKS FOR THE RESPONSES GUYS!!

I checked the voltage output wave with the oscilloscope in my scanner (both with battery connected and without) it seems to be good. Luckily I also own a 525i so I was able to compare the alternator outputs for both vehicles. They were very similar. So I'm gonna rule out a bad alternator.

As for the internal high pressure Vanos line, I did come across this TSB:

It states M5's "up to January 2006" for the internal high pressure line and M5's "from July 2006" for the pump , mine is 12/05 build so it falls in the high pressure line.

I guess my next step is to rule out the accumulator. Ive already unplugged it during idle and was no change to the pressure. I was planning on giving it voltage directly but, IDK if its feed just a simple DC voltage or if its some kind of pulsed wave.

Lets say my accumulator is good and my internal line is ruptured or pump has failed. I wish there was a way I could determine which. The only solid information I have is that when the engine is cold I get around 50psi, when warm I get 270psi. I don't want to spend $2,600 on a new pump if I don't need to-the line is under $200.

Are there any special tools/procedures I need use/know to replace it? I really can't find a detailed service manual on exactly how to remove it (besides TIS). I've looked around and can't seem to find any posts of someone that has done it themselves.

Thanks for that link!

But, what I cant understand if the crankshaft signal is out of whack why the Vanos oil pressure would be so low all the time. As you mentioned before, the DME could be dumping the Vanos pressure based on what it sees from the crankshaft signal for a fail safe mode. Correct me if I'm wrong, the only way for the DME to drop the Vanos oil pressure (for engine fail safe) would be the accumulator?

The funny thing is that I never get a "Vanos low oil pressure" code the whole time im messing with it beside a couple of times when I loosen the top banjo fitting just to see if oil would squirt out-that's the only time I got a "Vanos low oil pressure" code. So I know the DME is aware of monitoring the Vanos oil pressure. If the DME won't let the engine rev above 1,000rpm do to low Vanos oil pressure (because of the high pressure line or pump) I would think it would give me that "Vanos low oil pressure" code all the time. Unless like you said the DME is aware of the crank shaft code and dumping the pressure on purpose via accumulator then it would not spit out a "Vanos low oil pressure" code because the DME is doing its job.

I actually purchased this car broken like this so I don't know anything about the history. I would think the odds of the two problems (low Vanos oil pressure and the crankshaft code) to happen at the same time would be pretty low. This leads me to believe the crank sensor code could be the source of my problem.

So, In my next session...

I will run 12v directly to the accumulator and see if my pressure does indeed go up. I did try to unplug it while at Idle before and got no change in pressure. I'm thinking I can also cap off one of the lines at the accumulator and see if the pressure does jump up-in case the accumulator itself is bad. Assuming this is the only way the DME can drop the pressure, then I will know it has to be a bad line or pump regardless of the crankshaft sensor?

resistro said:

Thanks for that link!

But, what I cant understand if the crankshaft signal is out of whack why the Vanos oil pressure would be so low all the time. As you mentioned before, the DME could be dumping the Vanos pressure based on what it sees from the crankshaft signal for a fail safe mode. Correct me if I'm wrong, the only way for the DME to drop the Vanos oil pressure (for engine fail safe) would be the accumulator?

The funny thing is that I never get a "Vanos low oil pressure" code the whole time im messing with it beside a couple of times when I loosen the top banjo fitting just to see if oil would squirt out-that's the only time I got a "Vanos low oil pressure" code. So I know the DME is aware of monitoring the Vanos oil pressure. If the DME won't let the engine rev above 1,000rpm do to low Vanos oil pressure (because of the high pressure line or pump) I would think it would give me that "Vanos low oil pressure" code all the time. Unless like you said the DME is aware of the crank shaft code and dumping the pressure on purpose via accumulator then it would not spit out a "Vanos low oil pressure" code because the DME is doing its job.

I actually purchased this car broken like this so I don't know anything about the history. I would think the odds of the two problems (low Vanos oil pressure and the crankshaft code) to happen at the same time would be pretty low. This leads me to believe the crank sensor code could be the source of my problem.

So, In my next session...

I will run 12v directly to the accumulator and see if my pressure does indeed go up. I did try to unplug it while at Idle before and got no change in pressure. I'm thinking I can also cap off one of the lines at the accumulator and see if the pressure does jump up-in case the accumulator itself is bad. Assuming this is the only way the DME can drop the pressure, then I will know it has to be a bad line or pump regardless of the crankshaft sensor?

Click to expand...

So, all the accumulator consists of is a steel cylinder with a gas bladder inside of it. It has a solenoid valve that opens when the engine is running and shuts when off to maintain pressure inside if for the next start.

It serves two purposes:
- primary means of pressure/fluid delivery to system loads
- pressure transient damping

Think if it sort of like a capacitor for fluid pressure instead of electrical charge.

The accumulator can not reduce pressure. All it can do is make up for pressure drop when system demand over comes pump delivery capacity.

The pump has a built in pressure regulating valve though. I suppose its possible that the regulating valve spring is weak and dropping pressure. But if you see any variation in pressure with engine RPM, that probably isn't it and that would be more consistent with either a leak in the discharge piping *or* a bubble in the VANOS system.

I agree the crank sensor is a separate problem from the VANOS pressure. The VANOS pressure may in fact be fine and just needs a good ventilation to remove the trapped air, restore it to a solid system, and get rid of the compressible bubble. Unfortunately, you can't do this without the engine running properly and the flywheel and/or CPS. I would really start here by either pulling the transmission and inspecting the flywheel teeth, or doing so through the CPS hole with a boroscope and someone to manually bar the engine over.

The VANOS pressure will be much easier to sort out after the engine revs properly.

Bad flywheel teeth

Dropped the engine and tranny today. Man it was a PAIN!! Turns out I did have a bad tooth on the flywheel cause by a broken rivet just like the TSB described. That was that extra signal I was getting on my scanner. So I'm gonna pull the pan next weekend to replace the HP Vanos line and also replace the rod bearings. I posted pics below of the teeth and the actual rivet I found.

Some things I would like to find out though..

1) What kind/where to get the rod bearings, rod bolts, HP Vanos line (dealer only I assume), oil pan gasket (dealer ?), NGK plugs. Should I go with OEM or those "coated" bearings I've been seeing on the forum?
2) I think I'm going to go with a used flywheel and clutch that Troy Jeup has for sale and says it has under 500mi...? Good Idea? This would save me $1k from the Luke flywheel and clutch set I saw on Ebay for $1,800.
3) The correct way to torque the rod bolts?
4) Anything I should do while the engine is out?

Any advise on doing the clutch/flywheel replacement? I'm gonna replace the throw-out bearing for sure. But, I have been reading about the guide bushing-but I'm totally confused.

It would be great If someone could shoot me some links on what brands to get and where to buy from. The consensus on the forum seems to believe OEM is best for bearings and bolts.

Bad High prressure Vanos line

Took the Vanos pump and line appart and capped off one bottom of the Vanos line with a bolt and nut using the copper washers and shot a little compressed air through the top with a fitting I had lying around with a blow gun, around 50psi. It was absolutely obvious I could feel air coming out of around the middle of the braided line even though I was using the tip of the blow gun against a small hole of the fitting I had (not a perfect fit).

THANKS GOD it was the line!!