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Old 01-28-2024, 04:02 AM
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Quote:
Originally Posted by cfoss View Post
Well I spent another interesting day on the bmw.

I did a leakdown test on the engine just to confirm it's all ok. I set both banks to max valve open just for fun. I cranked each cylinder to 80 psi. Here are the results:

Cyl 1 76
Cyl 2 76
Cyl 3 76
Cyl 4 77
Cyl 5 76
Cyl 6 77
Cyl 7 76
Cyl 8 77

So, very very good in other words.

Then I had an idea on how to check the valve lift mechanism: Rotate the engine so that the intake cam lobe is at max and then rotate the valvetronic motor from the valve closed stop to valve open on each cylinder and see if they are similar.

The way I did this is to use the leak down tester, set to about 20psi input. This is not enough to rotate the engine, but is enough to determine when the valve opens.

I have read that the valves will be open a tiny bit even when the lift is at minimum, but my valves are closed at the minimum stop-so the test worked.


Here's a vid of how I did it:

https://www.youtube.com/watch?v=eQ0ptrnwz5A

The four valves were very similar:

Turns before open:

Cyl 5: Crack: 1.5, Open: 2.0
Cyl 6: Crack: 2.0, Open: 2.5
Cyl 7: Crack: 1.5, Open: 2.0
Cyl 8: Crack: 1.0, Open: 1.5


So it seems the cylinders are pretty synched. Looks like mechanically the valvetronic lift mechanism is fine.

Onward....

Next up, I'm going to check that the cams are still in time with the engine with the allignment tool. I expect that they will be fine, but while I'm here I may as well eliminate that possibility.


Chay
Clever. I have discovered a way from software to eliminate the valvetronic and force the engine load control through the throttle body. It's temporary for a drive cycle. I've been driving the car for 30,000KM this way without any misfires. I finally found a wrecker engine and replaced the camshafts on the cylinder bank that showed visual wear on the exhaust and intake lobes, so I don't need to carry the computer with me every time to use the car. There's a russian guy that makes an android-app with the common cheap bluetooth obd adapters that runs the same code, but you don't need a computer, tool32, and an adapter.

But your original post is strange. You didn't describe what your fault is. Otherwise I would have mentioned something. I thought you were just curious on how to test the motors.
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2003 4.6, esotril blue, over 215,000KM. Every previous owner failed to keep up the vehicle maintenance. Restoration project.
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