Fuel trim
Posted: Wed Jul 22, 2026 6:28 pm
Multiplicative is of the scale as is LTFT so the suggestions are big vacuum leak, low fuel pressure with possible ccv diaphragm split, o2 pre cat sensors or MAF. Odd thing is that it is running well, no stalling, hesitation or any other issues. I was just playing about with the diagnostics cos I was bored. So started with a smoke test. Had to abandoned that as there was so much smoke pouring out from the inlet pipe where it is jubilee clipped to the throttle body, throttle body to inlet manifold and the bit the throttle body connects to has another seal. Ordered the bits from BMW. Got them fitted and the smoke machine back on and one of the pipes from the LPG injector to inlet manifold is leaking. Fixed that and got the fuel pressure tester out. 2 bar pressure. Changed the filter, what a bloody difficult job just getting to the filter. Run fuel pump from diagnostics and get 2 bar. So now got a fuel pump on order. Oh, the new heater valves I fitted in January are letting hot air bleed through when a/c is on, the bottom couple of vents allow the hot air in. Changed them, luckily they were 10 year warranty so should get my money back. Hopefully when the pump comes that will cure the pre cat o2 sensors permanently reading 1.04 and that will be all the problems fixed that I didn’t even know I had. It’s been a great week.