p38

Hi
I have a 2001 p38 4.0 with lpg it starts perfectly on petrol but is gutless and if cold will backfire for the first half mile until it changes over to gas (no backfire if already warm )but once it changes to gas it runs beautifully . I tried to tow my caravan with it on petrol it felt like it was running on 5 cyclinders and I could,nt get it over 30mph yet on gas its like a rocket . Has anyone got any ideas ,Thanks

take it into a garage with the laptop, have the adaptive learning values reset for the fuel,
i had this problem originally, but found out after plenty of resets, start on petrol run until normal temp then change to gas, before switching engine off switch back to petrol for about 20 secs, no more resets for me
if you are not going to switch engine off and not going to restart until completely cold again, you can change to gas when cold, but make sure that you switch engine off whilst still on gas then switch back to petrol

al-one-arm said:

take it into a garage with the laptop, have the adaptive learning values reset for the fuel,

Click to expand...

I thought of that as well, problem for me was that the engine won't be running closed loop and hence using the adaptive values until the engine is warmed up. As this problem is apparently happening when the engine is cold, it seems to rule out any closed-loop related issues.

I'd take it to a garage and check for any fault codes, maybe the ECT (engine coolant temperature) sensor has failed ?

when my adaptive values were 'out of range' ran as sick as a dog when cold, slow take off, very bad acceleration, hills were nearly impossible, originally i sprayed loads of carb cleaner into the butterfly area(to get rid of all the black)but especially the small hole on the side for air to get through bypassing the butterfly, this improved it a lot, but would still only tickover feeling like it was running on 7 1/2 cylinders, as soon as the adaptive values were reset, perfect again

Thanks guys