Hi all,
Have a p38 97 4.0se.It is lpg converted and running fine on this no problems.The problems start when running on petrol rubbish idle,cutting out on idle too,whilst driving on petrol you get hesitation and sometimes a slight backfire and like i said earlier running on gas its fine.Any idea's or thoughts would be greatly appreiciated.Thanks

Ah forgot to say i have changed plugs and tried a new air flow meter still the same.

 

i have the exact same problem with my vehicle 1995 4.0se range rover (lpg), how did you resolve this may i ask?

 

I do have a similar problem. I own a 1988 Range Rover with a 3.5 V8 (auto). It runs on LPG and petrol. However, it backfires on petrol and LPG (on occassion) and has already blown off the bottom of the air flow meter which I got replaced. However a few days ago it blew out the pipe connected to the meter.

I was told that I could install some sort of pipe which makes it easier on the air flow meter if it backfires...

Would appreciate it if someone could advise on some permenent solution as to how to solve this problem.

 

owners manual for my 95 4.0 SE states to use 92 or 91 octane fuel minimum

 

The ignition timing is different for running on LPG than it is for petrol. This could explain your problems. You need more advance when running on LPG since the flame front is slower.

A lot of people set the timing halfway between ideal petrol and ideal LPG advance which is, at best, a compromise. YOu can get automatic timing advance modules that advance / retard the timing depending on whether you're running with petrol or lpg. I've never tried one and would be interested in hearing about anyone that has. I know that RPi do kits and I've seen others on ebay.

Good quality spark is vital for good running on LPG. Check HT leads / distrib / plugs, etc.

Backfires are pretty bad news for the air mass sensor.

Most RR LPG systems use engine depression to meter the LPG - bit like carbs - effectively bypassing the ECU. If you're running nicdely on LPG but having problems on petrol (once your timing is sorted) then I'd start looking at problems with air mass sensor, water / fuel / air temp sensors, etc. Basically anything that can send bad data to the ECU.

Hope this helps.

Ben.