P0021 issue, at my wits end.

[redimension]

Hey guys, thanks in advance for taking the time to read this and offer help!

I rebuilt the motor in my '02 540i about 4-5 months ago. I retimed it myself and everything was good. During the rebuild I did not replace the seals in the vanos units and Ive had that nice start up rattle ever since. So this last weekend I tackled the job. I rebuilt the vanos units per Besian's instructions and everything went smoothly. I reinsalled the vanos units, retimed the motor and put it back together. Ran smooth, no isssues! In fact, the motor felt better, seemed to have more power after shifting (manual).

Then all of the sudden, yesterday, one week later. It starts having a rough idle and throwing the p0021 code. (I'm not sure if the code was there last week, I didnt check because everything sounded great. No cause for concern. This is about the 6+ time overall I have timed this motor) There is a ticking sound as well. Swapped cam sensors, code did not follow. Removed the electrical connection for the vanos solenoid, p1526 appeared and p0021 went away. I also checked all the pins at my dme, everything is straight and connected properly. 110% sure that the timing blocks were flat on the head during timing, vanos was retarded, wheels were in correct time and everything was torqued down to spec.

As I cannot find any hard evidence online to the cause, I am looking for an answer before I start tearing the motor down again to retime. Is it possible that I have a bad Vanos unit? Im 99.99% sure that my timing wheels are straight, they have never been in a place where they could have accidentally been bent or anything.

Thanks for the help guys!

[edjack]

http://www.obd-codes.com/p0021

[rf900rkw]

P0021 means the *measured* cam timing is off by more than 10 degree while the VANOS is unactivated (retarded). In reality it has nothing to do with the cams themselves. It's the crank trigger vs the cam wheel.

What sort of scanner equipment do you have? INPA?

[whiteghost1]

Like Randy said it's probably your trigger wheel that is slightly off, and not the cam timing. I chased this code for months as I had the same symptoms (CEL + rough idle), probably adjusted the trigger wheel a 1/2 doz times without success; trying advance/retarding it to great detail. Nothing - was getting desperate and pulling my hair out, almost to the point of throwing relevant parts at it......
Then one night on a whim I decided to try adjusting it to the original marked position for $hits & giggles, one last go before buying any associated parts. Just like that the idle smoothed out and the CEL disappeared, so whatever I touched in the process fixed the problem for good.

[redimension]

P0021 means the *measured* cam timing is off by more than 10 degree while the VANOS is unactivated (retarded). In reality it has nothing to do with the cams themselves. It's the crank trigger vs the cam wheel.

What sort of scanner equipment do you have? INPA?

I have access to INPA, although I have not used it for this issue yet. I just used an off the shelf scan tool to read my p0021 code.

Like Randy said it's probably your trigger wheel that is slightly off, and not the cam timing. I chased this code for months as I had the same symptoms (CEL + rough idle), probably adjusted the trigger wheel a 1/2 doz times without success; trying advance/retarding it to great detail. Nothing - was getting desperate and pulling my hair out, almost to the point of throwing relevant parts at it......
Then one night on a whim I decided to try adjusting it to the original marked position for $hits & giggles, one last go before buying any associated parts. Just like that the idle smoothed out and the CEL disappeared, so whatever I touched in the process fixed the problem for good.

How much is slightly?! I would have to imagine that there is some sort of leniency/tolerance built in. Timing the trigger wheel, will not be dead set perfect everytime. I used the tools to set the timing wheels. There isnt much variance or wiggle room allowed.

Really, I feel like all I can do at this point is pull the covers back off and time it again. Just frustrating because I'm certain that everything was done right.

[rf900rkw]

You are allowed 10 degrees crank, which is 5 degrees at the cam. It doesn't take much.

If you have INPA installed, then stroll on over to the Diagnostic Software forum and download "Testo" INPA doesn't show the cam adaption. Testo does. Once you see the adaption values, you can determine how much to move the wheel, and which way.


http://forums.bimmerforums.com/forum...ime-graph-view

[vinyldude]

I found out, too, that it does not take much for the engine to generate that error.

http://forums.bimmerforums.com/forum...ls-replacement

As already said, it could be the cam timing that is off, or the trigger wheel, or any combination of both.

In my case I believe it was the cam timing.

What was suggested to me was, take the valve cover(s) off, put the crank pin on, tighten the chain, and check timing with the timing blocks. When the intake cam is held in the fully retarded position with a wrench, the timing blocks should easily slip back and forth while laying flat on the head in order for the timing to be correct.

If you find the cam timing to be correct, you can verify and adjust the trigger wheel positions using drill bits in the timing cover holes and an open wrench without taking the timing covers off.

If you have INPA, and get the same error message that I did (screenshots are attached to the thread mentioned above) where wnwi2_u value shows as being negative, it could be a sign of the same cam timing issue. I believe if the cam timing is detected to be even one degree "negative", i.e. over-retarded, it will trigger this error code. My problem was, the intake cams had been counter-held slightly too hard when the sprocket bolts were tightened and it had advanced the intake cams just a tiny bit to be out of position. One has to use the "hold the cam and slip timing blocks in and out" method to detect this problem. The same could happen if the trigger wheel is not set correctly, but my theory is that it is on average less likely to happen.

You can also make the code to go away by adjusting the trigger wheel alone, possibly to a slightly off position what the trigger wheel timing tool shows you (in case the cam wasn't set exactly right), but it will only hide the cam timing error.