BMW E36 PNP idle issue

[BLAKE AuST]

I've had my car tuned and it runs quite well, it wasn't wired for hold power so the idle stepper would often pop on startup and it would sometime stall on deceleration.

 

I've now wired it for hold power which works and no more idle stepper pop.

 

While double checking my wiring (car was an M52 i rewired to M50) i found that the idle stepper motors 2 wires going to AUX 1 and AUX 2 were reversed, i've fixed this but now the cars idle is erratic and its running really rich so i'm not sure if the tuner put a work around inplace or what for my dodgy wiring

 

i have attached my tune and a log of the issue if you could please take a look.

 

I also found the below, i have it wired as per the BMW and Link documentation but the ECU shows AUX 1 to be Open instead of Closed.

PC Datalog - 2023-07-24 12;33;10 pm.llgx M52B28-before2.pclx

[DerekAE86]

I didn't think the E36 had a "stepper" idle motor. Appears to just be a 3-wire PWM solenoid?
In which case the labels in PCLink are actually backwards. The Helpfile is correct.

But if you think it's running backwards now just change the "Aux1 Active State" from High to Low, that should flip the operation.

 

Also it appears your over-run fuel cut is kicking in because you're idling so high.
You might want to raise the de-activation threshold or just turn off over-run fuel cut all together until you can sort out your idle situation so it doesn't mess with you.

[BLAKE AuST]

Thanks Derek! that makes sense, 

I changed Aux1 active state from High to Low and the idle is much better and disabled over-run fuel cut for the moment.

I've uploaded another log, as the idle still floats around 780 to 1030rpm or so, i'm not sure if its just bouncing between 2 cells on the fuel map or some other setting is wrong.

Chris

 

PC Datalog - 2023-07-25 6;17;26 pm.llgx

[Adamw]

The wiring and aux state was correct in the first place.  If you have reversed the wiring then aux 1 active state should be reversed to low.

The minimum clamp needs to be set to 20% or higher with these valves as 20% is fully closed, below that they start to open again. 

So provided your aux active state/wiring is correct now (either both the same as they originally were or both reversed would be fine), then I would change the min clamp, flatten out the fuel table around the idle area and if idle still doesnt reach target then you may have an air leak or need to close the throttle a little.