Evening all, I've got a 2001 facelift 320i with the M54B22 lump. It's converted to LPG and we're having issues getting it to run right on LPG (this is not the request!). Basically it runs perfectly on petrol but on LPG stutters and misfires coming off idle and doesn't like sitting at 30-50 MPH. While running live data the other day on my Sealey code reader (I'd just used it to clear the management light caused by poor LPG running) I noticed that TPS percentage was reading 0. I was keeping the speed steady at around 40MPH, thinking this was strange I booted it and it went straight up to 100% and happily showed me readings under that until I let off to around the throttle position I was holding to stay at 40.
Having thought that was odd when I got home I did a little test - gently increasing the throttle on idle to see what happened on the code reader, the engine revs reached nealy 3k before I was seeing any throttle percentage on the live data. It went from 0 to 1.something as you would expect not leaping up to a large pecentage and kept increasing steadily as I slowly increased the throttle.
My question is - Are any of you still running a BMW with the M54 engine on fly by wire throttle and if so do you have a code reader with live data? If you have, would you mind just seeing if yours do the same? Because my LPG system learns from the petrol ECU through the OBD2 I think it's learning incorrect data about the current throttle position until you're what I think from "foot feel" is over 1/4 throttle.
I realise most peoples answer would be "take it back to whoever converted it" but I'm doing that as well! The guy who did it runs a very successful garage and has converted many cars before this with no issues. This was his personal car and he originally converted it for himself but using a Polish kit he'd never used before (thinking he'd get back into the LPG converting again using the cheaper Polish kits) and nor had he done an M54 before. I've since bought the car from him as he had just left it sitting and had no real use for it anyway and the poor running has been an ongoing issue we've been trying to solve.
Sorry for having run on, I figured it was better you had some back story! I do have one last question - Obviously the throttle potentiometer on the pedal is functioning as it should as the slightest press from rest results in increasing engine speed, so where is the TPS that the OBD2 is reading from? Is it separate as on cable operated throttles or is it built into the electric throttle body?
Thanks if you've managed to get this far and are still awake