Yes! I have a wiring harness and ECU for an M50 with Vanos. I bought it used and everything seems to work ok except for the knock control. My car does have an M52 short block, but its running in OBD1 with all of the M50 hardware.
Its basically just a 2.8Liter M50.
I mentioned this in case maybe I had some of the settings messed up in my config, but other than that, its an M50 other than the block.

Thats good to hear that the knock chip is working properly, Im hoping its not something else inside of the ECU.

So,
I did what you said. I checked the grounds from the knock sensor plugs and verified that both plugs are properly grounding through the ECU to a common ground point.

I did notice that I had the sensor wires swapped!! I guess when I pulled this wiring harness out of its doner car year ago, I must have mislabeled these haha. Glad I caught that!

While I was in there, I also took off both knock sensors and wire brushed both sensors smooth as well as the mounting points on the block.

Is it possible that the knock control simply wasn't working because I had both sensors swapped? To my understanding, Swapping sensor plugs would have simply skewed the end result as for setting up the knock frequencies/ tuning the sound table. I don't think it went into a fail safe mode because it knew I had the sensor wires swapped.

Also, Last question. I understand that these Bosch 2 wire sensors are grounded through the ECU, but is it possible that they are also grounded on the block itself? Just an idea.

Thanks again Dave for your help!
Much appreciated!

Hello e30sforlife,

A wiring harness from an m50 Vanos ? But the ecu was also ordered for m50 Vanos or for m52 (almost certain the ecu you ordered must be m50 vanos otherwise it would not run) ?

If your ecu was orderd for m50 vanos than your connections seems good (knock sens cyl4-6 mot88/pin69, knock sens cyl1-3 mot88/pin70, knock gnd mot88/pin71).

According to my review of your vemslog, knock control was setup correctly for sampling; so no isses there and knock chip is functioning correctly.

The only other thing i can think of is that perhaps the knock sensors are not getting ground.

Could you check if your knock sensors are getting ground by measuring resistance with DVM across mot88/pin71 (with wiring loom plugged into ecu not powered) and chassing gnd ?

Best regards,

Dave

Hi Dave,
I tested the wiring harness for continuity between the X6000 ECU plug and knock sensor pigtails. Everything looks Okay!

The Bank 2 Knock sensor (cyl 4-6) gets power from Pin 69 on the X6000
The Bank 1 Knock sensor (cyl 1-3) gets power from Pin 70 on the X6000

Both sensors as well as the shields are grounded at pin 71 on the x6000.
Im using a wiring harness from an M50 Vanos FYI.

Is there some way I can test The knock sensors themselves? They are both brand new Bosch Sensors! I doubt both of them went bad at the same time.

Are there any features in VEMS Tune that for some reason disable Knock Control? Could there maybe be a bug in the program or possibly my hardware?

Again, I really appreciate your help Dave!
Thanks

Hello e30sforlife,

If the knock sensors are using BMW stock wiring that should be fine, no noise issues to be expected there.

If you get back to me with the continuity measurements, like:

pin 1 knock x sensor plug goes to mot88-xx
pin 2 knock x sensor plug goes to mot88-xy

etc. we'll work from there.

Best regards,

Dave

Hi Dave,
Sorry for my late reply. Both sensors are brand new and I'm pretty sure they worked on my stock ECU. Ill test for continuity and get back to you.

Also could it be possible that somehow the sensor signal is being disturbed by another sensor wire being too close? Doubt it, but I do know these things are sensitive.

Thanks for you help!

Hello e30sforlife,

From my review of your vemslog it seems the knock chip is functioning correctly but not picking up any signal from the knock sensor(s).

Could you check if they are correctly plugged in/have good wiring continuity to m52 mot88 plug ?

Best regards,

Dave