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Old 07-13-2021, 08:24 AM
Nolimite39 Nolimite39 is offline
Join Date: Jan 2020
Location: Houston TX
Posts: 322
Nolimite39 is on a distinguished road
Originally Posted by andrewwynn View Post
Each of the times I've done chain guides on M62tu I got P0021 error.

Resolved with real-time measure of the requested vs. actual cam angle which were not well matched to confirm computer didn't see the cam matching request with refurbished vanos and just redone timing with a new chain.

I wasn't sure from the read above what was the fix.

Did you do like me and hook up the timing alignment jigs symmetrically? Oops.
I have the GAS Master Tool Set so the timing jigs are labeled per bank so that wasn't the issue.

Here is an excerpt from my post on Bimmerforums explaining the resolution and why I didn't catch the issue the first two times I opened it up

"UPDATE: I finally carved out enough time to get her opened back up. So my last hunch was spot on. The Bank 1 Exh and Int cams were dead on and the tools slipped on dead flat (intake was turned manually until it stopped), the Bank 2 Exh and Int cams were both ~20* retarded (didn't measure the exact angle, I eyeballed it, it was enough for me). The two contributing factors it appears were:

1) When doing the timing the previous times I didn't have the chain tensioner tool as tight as I should have. I was scared to overtighten it previously because of all the warnings in the GAS and Beisan instructions. This time I almost bottomed the tensioner bolt to the tool body, the fact that the chain has had a chance to run some and rotating the engine a few times by hand while taking up the slack helped settle everything prior to timing the engine.
2) Turning the crank CCW even the slightest bit creates a big enough difference in the position of the chain and the relative position of the cams which likely made up the rest of issue. If you miss the mark when trying to set TDC DO NOT ROTATE CCW, turn the crank CW the entire 720 degrees!

Further I will state the hypothesis that the 41.93 crank degrees which coincides 20.965 cam degrees is in fact the physical limit of the VANOS. Which makes sense because for proper operation of 20* adjustment 2.5% is an acceptable added engineered tolerance. No one has ever shown more than 41.93 and 41.93 has appeared often enough to confirm that its not random."

Here's a link to the full thread if anyone is interested.
Again Daily Driven SC'd 4.6iS, whats the point of having a sweet ride if you dont use it all the time.
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