HELP.....Post Timing Chain/Vanos Job Woes

[V8 00USH]

Need some assistance if at all possible please guys - hoping someone has seen similar to my current predicament.

As most of you know I've just finished putting back together my 4.6is after a rather lengthy timing chain & vanos seal replacement job.

Thread here incase you missed it - https://xoutpost.com/bmw-sav-forums/...ventually.html

Anyway, after it not initially starting after the rebuild due to the fact that I'd locked the engine 180 degrees out which meant that the trigger wheel was 180 degrees out - so once I'd resolved that the engine started more or less first try and appeared to be running well....or at least so I thought until I refitted my secondary air system and the exhaust blow was removed and I got to hear it idling properly I could tell all was not right and it was missing/very lumpy. I got my Snap On Solus scanner to check the live data.

The smooth running values for each cylinder were showing as follows...

Cyl1 - 9.5
Cyl2 - 5
Cyl3 - 2.5
Cyl4- 2.5
Cyl5 - 0
Cyl6 - 0
Cyl7 - 0
Cyl8 - 0

Bank 1 exhaust was luke warm compared to Bank 2 which was hot - it would appear that there was hardly any combustion going on in bank 1 - if any!

I got INPA on the go and checked the rough running values which painted an even worse picture with cylinder 1 being the worst and cyl 6 being the best.



I went over everything I could think of, tried adjusting the cam trigger wheel on bank 1 both ways (even though I'd used the proper alignment tool at timing stage), checked compression which was good at circa 180psi across cylinders. checked spark, checked fuel - all of which seemed to exist, plugs weren't fouled up either and plugs were a normal colour.

So this evening I made a strange discovery - if I unplugged the coil on Cylinder 1 whilst running the engine would respond immediately and run almost perfectly, it would rev up cleanly and sound great. Also the rough running values would improve...



I immediately got to swapping things over between cylinders coil, spark plug and coil and testing after every swap however nothing made any difference - the problem still existed.

However, I can't help but think this is a red herring of some sort and is masking the actual issue. I think it's strange that it's the leading cylinder that appears to be causing an issue. I'm sure the fueling side of things takes it's start point from cylinder 1 cam position - if the ECU detects that it's misfiring in that cylinder then it will shut it down and possibly surrounding cylinders - that will then probably have a knock on effect whereby the other bank 2 will then try to overcompensate for shut down cylinders on bank 1 hence the rough running figures.

I feel it's all leading back to some kind of issue with timing even though I've done it twice using the proper tools and procedures - plus if the timing was off surely it wouldn't run as well as it does when I unplug cylinder 1 coil pack. I'm loathed to redo the timing again since it runs really well if I unplug cylinder 1.

Any clues guys - anything I'm missing - should I redo the timing yet again, could it be a vanos issue?

Either way it's driving me bonkers and has set me back days now!

Any kind of help appreciated. Thanks