M50b26tu vanos problems?!

[Hellfeldz]

Hi guys!
So been in the BMW sceene for a good while but now to the problem...
Recently did a m50b20tu stroker to 2.6l... usual b28 crank and the rest of the recepy.
Still using the same siemens ms40.1 dme.
Before taking everything apart, car was runing like a 2.0l does.
Now engine is refurbished and we are using all the original sensors it had. There is no 02 sensor used on it while I have it in my possesion.
When engine is cold, runs great, acceleration is bueno, vanoss works. Then after 10 min 5min of driving cant rev past 3k rpm when there is load, engine boggs down. When vanos is disconected, runs like a m50b26 would do.
now reseted timing 3x, tested vanoss functionality (with compressed air and manualy activating vanoss solenoid), disconected knock sensors. What I have not tried is dc cam sensor, but if thinking logically, vanos should not work. Oil pressure shows fine when this happens, using 5w40 oil.
Soon will receive o2 wb sensor, then I could tell if it leans out or gets too rich when going in the 3k rpm with vanos connected.

Anyone had expierence with this kind of setup? My other m50 bosh, m50 ms41 setups with b26 and b28 strokers have worked fine... exept some old wiring and bad crank sensor isues.

Cheers!

[Eric93se]

3k limit is what.people call limp mode, usually a sensor. Ohm test your crank sensor and remove and clean your speed sensor in the diff. (Or replace).

[Ghost129er]

'...remove and clean your speed sensor in the diff. (Or replace).'

Wait how does that help? I haven't done that in mine and am curious as to what all this would fix/what all this troubleshoots for.

[Hellfeldz]

Wait how does that help? I haven't done that in mine and am curious as to what all this would fix/what all this troubleshoots for.

So I checked everything and in the end disconnected the VSS. It solved the problem, no more limp mode. But still, i don't get it how does it changes the power output of connected vanos. Replaced the VSS with a used one, still not working. Could be some wiring isues... who knows, for now gps speedo it is 👍🏾

[Ghost129er]

This is the one in the diff, correct..? If so from what I've seen in the diagram for wiring, it's in line with the fuel pump level sensors on both sides of the tank - I used to have an issue where the fuel level and speedo both use to spazz and sometimes not work at all and had some wiring to fix under the seat which solved it.

[Hellfeldz]

This is the one in the diff, correct..? If so from what I've seen in the diagram for wiring, it's in line with the fuel pump level sensors on both sides of the tank - I used to have an issue where the fuel level and speedo both use to spazz and sometimes not work at all and had some wiring to fix under the seat which solved it.

Yes, it is one in the diff.
Hmm... learn smtg new every day, but never had a problem like that.
Cheers to that!!!

So I can update the topic with an 14point7 WB02 sensor. For now it shows the car quite lean... never had a stroker this lean. the 14point7 has an option to fit it as a narrow band as well, but nothing changes for now... will do some wire testing to see if really everything is connected right and give an update then.
Bit of change... I start asuming that the sensors is not working correct. And afr values are other way round, 11 is richer than 14, obviously��