LPG MPG - On Board Computer L322

[CyberMrT]

Just had a Prins system installed on my L322 4.4 V8 and was wondering if the on board computer should still read the correct MPG when using gas?

It seems to be going up and down inline with the type of driving I'm doing?

Haven't yet filled up so can't compare with actual use of gas?

I used to get average of 18.5 on petrol and currently the comp is showing 17.5? I would be quite chuffed if this is correct?

 

[wammers]

Just had a Prins system installed on my L322 4.4 V8 and was wondering if the on board computer should still read the correct MPG when using gas?

It seems to be going up and down inline with the type of driving I'm doing?

Haven't yet filled up so can't compare with actual use of gas?

I used to get average of 18.5 on petrol and currently the comp is showing 17.5? I would be quite chuffed if this is correct?

Think the computer only gives you what it thinks you use when on petrol. It has no way of knowing how much gas is going through the system.

 

[MirrorSignalSwerve]

There's a thread on the site about this already. Gives you all the technical info about the MPG display and how it calculates. I have LPG and use the average MPG reading as a guide only as its not really accurate. Your best bet is to use the trip meter and get your calculator out for the next few fill ups. same rules apply - drive it hard and it drinks more. I have a 4.6 on an OMVL single point injection. Mainly semi-urban driving returns about 14MPG. Horrifies me to think about it too much, but calming thoughts of 50p a litre for LPG seem to help.

 

[gavbriggs]

the obc(on board comp) shows the amount of fuel it thinks you have used/using. because the lpg systems emulate the injectors then the obc thinks you are still on petrol, it has no idea, nor cares about the gas, it will howver try to change its fuel trims but will not be able to affect the mixture.

given that lpg is roughly 15% less efficient then you will get15 % less mpg but your only paying half the cost so you save on price rather than mpg.

i get between 180 and 280 miles to 94 litres lpg, depending on driving style/conditions. on a trip to wales from rotherham i got 260 miles to 33 quid which for a 2.7 ton 4litre car i dont think is a bad deal!!

just comfort yourself at the thought of 50p a ltire, i love filling my lpg tanks up!

 

[CyberMrT]

Thought as much as I'm now getting 20-22 MPG on LPG on the on-board computer, I assume this is all relative if I calculate the percentage i actually get in real terms compared to the obc, then just reduce the figure shown by that percentage each time...

 

[gavbriggs]

summat like that!!! whatever the figure it will be cheaper than petrol!! and remember the obc is only a guide!!!