rusefi.com

Hi there i am trying to get my build going.I'm using a uaEFI board with a brand new harness and all new bosch sensors on a BMW M42 engine with 60-2 fatory trigger wheel and a 1 tooth cam wheel on the exhaust cam with VR sensors in crank and cam.So far it was going well i have installed a lot of other standalone ecus.The car is currently starting and driving,but currently i have 2 problems with my build.

First problem,i cant get the board to see any rpm from the crank VR sensor on VR1 input,while VR 2 works perfectly (i have swapped wires and scoped the signal up to the board,I get a perfect 60-2 signal up to the board and i am using proper shielded cables).The problem is i have 2 VR sensors one for the crank and one for the cam,so i need both the VR inputs working to get cam sync and sequential ignition.Has someone had a simmilar experience and can help? I cant find a hall sensor which would fit the cam mounting hole,thats why am trying to get it all working with new original BMW sensors.

The second problem is much less of a problem,i get a lot of noise on the board when the wideband o2 heater is running,sometimes its so bad that the board registers rpm and fires injectors and coils with the ignition on without the engine running.I have checked grounds and powerfeeds multiple times now.

I tried for days to fix the issues,but now i need help from someone more experienced with rusefi boards.I can send remote access,even willing to pay someone a nice dinner for helping to fix the problem.

Without tune and log we are blind, please share your tune and your log.

Two VR channels are of different nature - one uses ASIC max9924 but has a 85ms timeout making it not suitable for small tooth wheels, another one was designed by @mck1117 that one does not have timeout but you are in charge of tuning it with feedback voltage.

AndreyB wrote: ↑

Sat Jun 01, 2024 1:40 pm

Without tune and log we are blind, please share your tune and your log.

Two VR channels are of different nature - one uses ASIC max9924 but has a 85ms timeout making it not suitable for small tooth wheels, another one was designed by @mck1117 that one does not have timeout but you are in charge of tuning it with feedback voltage.

Thank you for responding.I will share the tune once i get to my work computer,but i dont think that its a settings issue,i get no signal whatsoever in trigger oscilloscope ,but have a perfect signal using an external oscilloscope on th vr+ c18 and vr- c19 input,while the same software settings but selecting c17 vr2 as input in softvare and solering the cable to this input works fine and the car revs ok,i didnt notice any timeout or simmilar on that input as this is the one using max9924.I have the problem on the vr1 input using the different ic. Can you elaborate on the tunning with feedback voltage part,i cant seem to find info in the documentation about it? I looked at the traces on the board but cant seem to find any way of hardware tunning?

A little update ...I have got the car running without the cam sensor,I dont have time at the moment to fight the VR1 input as i cant find any information how to tune it...

So far i really like the ecu it is running pretty well with 630cc injectors,R8 coils and a custom intake.Tunning the VE table was really fast with the Tunerstudio autotune plugin,the car is perfectly driveable within one hour of driving.Still need tuning the timing table and other stuff on the dyno but for now im happy.I also have a bit of a problem with the ecu not starting up immediately when turning on the key,but i have to wait a few seconds before it boots,i think its voltage relatad as it immediately boots if I plug it in my laptop.

I have designed the original discrete VR with a friend, it was originally supposed to work with an input threshold from the ecu, it can't work without.
I added the possibility to add resistor, for low noise VR it is enough.

Matthew adds a latch to allow the polarity of the VR sensor to be ignored.

You need a signal from PD14 pins, the VR_DISCRETE_THR or OUT_PWM_6.

I don't know how it is supposed to work with UAEFI, you can try 90% on general purpose PWM1 and 10%. The original discrete VR used an inverted PWM signal, 90% for high sensitivity and 10% for low sensitivity, you probably need 90% for cranking and 50% when engine runs. (and less with few teeth cam sensor)

but the problem is certainly a lack of "input threshold" signal.