4.6 p38 lpg mpg

bazzahurst · Jan 23, 2010

Hi all,

My screen tells me im averageing 15.2 mpg but when i fill up with lpg it actually works out at 8.5 mpg, this is after driving very stedily!! the car has had the engine tophat linerd 10,000 miles ago. and i have just had the head gaskets changed and the radiator and thermostat. Any ideas why the mpg is so low? my last car was a 4.0disco on gas and I averaged 11 to 15 mpg on that driving it harder than i drove the rangey. Any ideas on what to do or is it just very thirsty?

bazzahurst · Jan 25, 2010

Hi again, drivin it a bit harder this week, and the display has dropped to 11.5mpg but real figure was only 6.8 mpg!!!!!! Any ideas?

gavbriggs · Jan 26, 2010

go get the lpg set up and serviced, it'll bring it back into line with how it should perform!

richwp · Jan 28, 2010

My 4.6 Vogue is returning around 19mpg on LPG.

kooky_guy · Jan 28, 2010

richwp said:
My 4.6 Vogue is returning around 19mpg on LPG.

Wow, really? Is that calculated from the pump or via the computer?

Mine's doing about 14 on lpg. Weirdly, it doesn't matter how I drive it, it always returns the same mpg.

bazzahurst · Jan 29, 2010

Took it in to the garrage today to play with the gas ecu settings, turns out it was set to throw in far to much gas, should do better now but time will tell

Irishrover · Jan 29, 2010

That's what the forum needs..feedback on problem progress and possible fixes.:behindsofa:

MAD-EYE · Jan 29, 2010

Not an expert on these things but the P38 that I had on LPG only ever managed 12.6 mpg around the town and only 16 mpg on the run. So i should say the auto P38 on LPG is Thursty, but hey LPG is only 50 - 60p per ltr so relatively cheap for a big lump.

richwp · Jan 30, 2010

kooky_guy said:
Wow, really? Is that calculated from the pump or via the computer?

Mine's doing about 14 on lpg. Weirdly, it doesn't matter how I drive it, it always returns the same mpg.

Thats calculated! I had a multipoint system installed in November - no noticable change in performance - and we've been getting around 19mpg consistently since.

kooky_guy · Jan 30, 2010

richwp said:
Thats calculated! I had a multipoint system installed in November - no noticable change in performance - and we've been getting around 19mpg consistently since.

Mine's a sequential multipoint too but I think it needs tuning as my petrol ecu keeps doing weird things with it's adaptive values. I think I understand why though now thanks to this forum!

AckAckFlack · Jan 30, 2010

Only had my p38 a couple of weeks but loving the LPG. It is a 51 plate 4.6 vogue and is bringing back 18 mpg (calculated from the pump) at an aveage of 53.9pence per litre.
Not bad for such a weight.

4.6 p38 lpg mpg

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