Saturday, April 11, 2020

STFT erratic at idle / Idle rough

I've been trying to diagnose an issue thats gradually getting worse on my 07 335i

Symptoms:
- After car has entered closed loop mode idle begins to jump up and down between 500 and 800 rpm
- Checking with MHD logger I can see STFT also jump up and down
- Eventually the car may settle at an idle of 700 rpm and STFT is solid. Turning off and the car back on causes the idle issue to start up shortly after again.
- The issue occurs any time its idle. Cold start (once in closed loop mode), warm start.
- Can be made worse by giving gas a light tap at idle, car seems to struggle to zero in on an RPM


Parts replaced:
- Injectors index 12 in the last 40000 km
- Spark plugs new in the last 10000 km
- Walnut blast 40000 km ago
- Coils replaced 40000 km ago
- Primary O2 sensors new (no help)

LPFP is holding > 70 psi
HPFP is bouncing between 650 and 750 psi at idle
No codes
Stage 0 map
Car stock and has moderate wastegate rattle

Resetting adaptations does not help

Has anybody experienced similar symptoms?