Poor MPG 4.4 on lpg and petrol

Hi all, we'll I've been struggling with MPG for a while, being on gas I've never taken much notice of the ones board computer unitll a couple of days ago, I couldn't get to a garage that sold sold and so decided to drive home on petrol. About 95 miles. I though as I was sat on the motorway I'd reset the computer to my shock averaged 15.1 @ 70 for about 20 miles. Much the same all the way home. A little less in traffic. Further more I have been driving local on both lpg and full fat and it's the same, around 8.8!

What's going wrong... What's everyone else getting and any ideas...

Oh incase its a 2003 4.4 vogue with 80k

Thanks

2003 L322 Vogue on LPG using a BRC Sequential system and 146K miles and I get 15.3mpg (Check out my fuelly account - click the little icon in my sig)

On Board Comp says I average around 19.1 whereas Brim to Brim checks out to 15.3

LPG is less efficent than petrol yet is around half the price.

Hi saint, is ur 15.3 around town or on a run?

hi there, if its a machanical fault its gonna be expensive,sorry to be abit streight to the point on ya,but its not gonna be cheap, the first two things you could look at are the air flow meter, and the lambda sensor(s) becuase if these components fail,the engine wont know what amount of fuel to put into the engine,so it will just pour it in! thats the first things id look at! i dont drive one,but i cant imagine the fuel costs with it doing 15 let along 8.8 mpg,thats probably worse than my 3.5 carb classic rangerover,with leaking tank,and missfireing on 3 cylinders coz its got a fooked cam! but it should do more than 8.8 mpg :jaw:

Just had a look at it fuelly. That's a really good tool! Your getting better than me. By a long shot... My best is 15 compared to your 20. Where is I'm averaging less than 10 around town.

drewsp38 said:

Hi saint, is ur 15.3 around town or on a run?

Click to expand...

Both - Town driving gets to about 13 or so and on a run best I have had is 17.3

My journey to work is a good mix of country lanes, duals and a few miles on a motorway, and I return 15.3

Hi tom,

Im wondering if it's worth upgrading my Hawkeye. I've not had it done since selling my p38, but looking like I need to. I'm thinking that if the airflow meter has a fault it will show up, as with any other ecu related faults.

I could only dream of a 17.3 lol my best was at 60, really light foot 16.1. Average around town, like I say, mid 8's. I need to to look furthering this! Grrrrrrrrrr

drewsp38 said:

I could only dream of a 17.3 lol my best was at 60, really light foot 16.1. Average around town, like I say, mid 8's. I need to to look furthering this! Grrrrrrrrrr

Click to expand...

mine does 23 around town
:bounce:

When did you last have your LPG serviced? They have to be done bang on time - either 200 hrs of driving in my case (stag system) or one year. I went over slightly and found that there was a white sticky liquid in the bottom of the filter case and in the ends of the LPG system pipes which shows contamination.

Also look at your engine breather - these need changing from time to time and have an impact on your mpg.

On petrol I get 24 at 70 mph and 18 avge overall. Town goes down to c. 16mpg.

Cost on LPG is 24p per mile, less than my td6 (25p)!

Thought I'd a 2p worth: I get around 14-15 mpg on petrol and work out 250- 260miles on 80 litres of gas. This is mainly trips of 16-22 miles or so, but remains fairly consistant. Car pulls like a train on gas or Petrol and since reading the posts on here I now only put in 97 octane go juice. Had a problem with the temperature sender on the LPG and it was messing around with the change over( Late, on / off again, not switching at all) but now as soon as it comes off cold LPG takes over. Also fitted LPG Plugs to it as these have worked very well on our LPG P38 - again no performance difference, actually runs better on LPG.