207 stumbles / hesitates

[oliverbob]

Hi There, really hope some one can help !! I have a 2008 1.4 petrol (75 bhp) 207 m play. It was converted to LPG last year. I bought the car 2 months ago.

It starts on petrol. switching automatically over to LPG after a minute or so.

It starts first time every time, but after 10 - 15 seconds, especially under load, splutters and hesitates. Frightens me to death trying to pull into traffic. Once it's on LPG, runs like a dream.

I've run it solely on petrol for a week, and also noticed a misfire at about 3500 RPM (no misfire when on LPG). On petrol, the car feels underpowered, and hesitant. It will barely go up hill - foot flat to the floor it just seems to "chug" before eventually picking up.

Thinking it may be a dirty / blocked injector, put some BG44K into the fuel tank, and ran it solely on petrol. Ran like a dream - all hesitation and stumbling gone. However, refilled tank and within 40 miles back to same problem !!

I've replaced plugs, ignition coil, MAP sensor - and even tried Shell Optimax but no change.

OBD is showing no faults / codes.

I can't understand why the injector cleaner temporarily cured the problem.

Any suggestions would be gratefully received !!