DTAFast / Dual Vanos question

[DaveSmed]

I have my S100 up and running on my S50B32 on pretty much the baseline tune (which isn't half bad really, just very conservative) and looking at the real time chart, I see some odd behavior from cam2.

In the chart below, the yellow line is cam1's target, and the teal line is where cam1 actually is. Both lines follow each other closely. Cam2's target line is not visible since its zero, but cam2 is definitely NOT showing any indication of tracking it properly.

Anybody see that before? I'm kinda limited on my diagnostic ability till Monday when i'll grab the decent meter and some backprobes out of the toolbox at work.

I ohmed out the two sensors and they seemed within range of each other. Once I get the meter and probes, I plan on looking at the AC voltage on the cam1 and cam2 sensors, and taking a peek at what the cam2 advance/retard solenoids are up to.

There's no audible or "seat of the pants" weirdness when it's wandering back and forth either.


My theory barring any kind of hardware failure is that the offset could be wrong and the cam is actually bottomed out at full retard and bouncing along as the solenoid commands movement against the stops. Plausible?

[nando]

can you bench test the solenoid?

[M3 euro ltw]

Dave, call me when you get a chance.


I have several ideas on this.

Guys, keep in mind S50B32.

So, 4 solenoids, in/out for each cam.

[DaveSmed]

Getting those solenoids out for a bench test is a bit of a PITA and I would definitely need to order a round of new seals for everything. Id like to avoid that until necessary (though its looking increasingly so).

I was messing with the cam control tables today and I can definitely make cam2 move around, but it definitely is not working right. I can actually hear it in the exhaust moving around at idle with no input. If I command the cam to 70, there is little/no change to the car. Change it to 75, slight change. 80, big change. 85, barely run/stall, and same with 90.

I was firing the solenoids with the diagnostic menu, and they seemed to be ok, though it is tough to hear if one of the two on either cam are faulty as I believe it just fires both. I need to throw a meter on it.

I'm starting to think hydraulic issues in the vanos now.

[DaveSmed]

Update:

Measured AC voltage on the sensors, found 3-ish volts on the intake at idle, and 5-ish on the exhaust. Thought I was getting somewhere until I found the tooth count is different between the two trigger wheels (dammit.)

Decided to swap sensors. Had to depin both because of connector differences, installed them and no change in voltage outputs, or cam control graph.

OK, I think I am starting to trust the sensor a bit. Poke around the DTA software and find a big difference in the PWM control maps, change the exhausts map to match the intake and the line smoothed out a good bit. Progress!

Add throttle, and it smoothed out a lot. Now if I command the cam to do something it looks like it tries to cooperate much better although it still likes to sit at the top of the chart when it should be at zero. When I command it to 10, it actually comes down a good bit (with throttle). Interesting. Idle is still producing an erratic line though (though not as bad) leading me to think a solenoid might be leaking internally.

Hooked the solenoids up one by one, and, albeit very very slight, there is a tiny audible difference in one of the exhaust cam solenoids.

[DaveSmed]

More graphs!

Held steady at 2200rpm, then dropped back to a fast idle. Looks like oil flow has something to do with it...



Right after I shut it down to freeze that graph in place, I restarted it and got this??



I wonder if manually working the solenoids while the car is running with fresh hot oil at ~2500rpm or so will do anything, might work out a piece of dirt or dead o-ring from the solenoid seat, if thats what the problem is...

[DaveSmed]

Oh, and lest I forget, a big thank you to Alex for all your help so far.

Anybody that wants to do anything involving 6 throttle bodies, he is the man to see!