Hi again guys,

i've had some WVO sitting around that I filtered and settled a while ago and the missus was down for the weekend so I chucked it in the car. It was only 6 litres and the range of what was in the tank was 120 miles so I reckon the mix was about 50/50.

It ran absolutely perfect, with no discenable difference other than I thought the MPG figure on the trip seemed a bit low. I however put this down to city driving and the heavy traffic as she uses the car out in the country where the traffic flows better.

Anyway shes half way home and noticed the trip doesnt want to show more than 53mpg despite her pootling along the motorway with the trucks due to the bad weather. Driving that way normaly would show high 60's.

Have i buggered it up or does the trip computer just learn as it goes along?

I should add that the trip when she left for home was showing about 70 miles in the tank and she put £20 in it to get her home so the mix now I guess is probably pretty low, just 10 or 15% at a guess.

EDIT......I've done a bit of googling and there are reports of bad readings when running veggie oil, something to do with the computer using viscosity to work out the flow and hence consumption. I'm therefore assuming that once it gets a nice full tank of clean derv it will then report accurately again!?!?

If it does not, can I get it recalibrated?

Edited 29 April, 201214 yr by capriman

You haven't said what engine the car has but PD engines and biodiesel/WVO do not go well together.

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The engine is an SDI, from previous posts, so it shouldn't cause any problems. The computers are notorious for being inaccurate but even if it's right I take it the WVO didn't cost a lot so higher fuel consumption would be acceptable? The only real way to check fuel consumption is fill to top and check mileage.

You might want to check the fuel filter. Bio/veggie does different things to the pipes than mineral (normal) diesel.

ISTR swapping from one to the other can cause deposits to lift and float into the fuel filter.

J.

The engine is an SDI, from previous posts, so it shouldn't cause any problems. The computers are notorious for being inaccurate but even if it's right I take it the WVO didn't cost a lot so higher fuel consumption would be acceptable? The only real way to check fuel consumption is fill to top and check mileage.

Thanks peter (and everyone else).

Yes it is an SDI.

The computer is normally not too bad. The long term average shows 64mpg but in real terms ie fill up and check mileage method, it averages 61mpg so near enough for me.

I'll get the missus to run the tank down really low and then give it a good drink and see if the trip computer recalibrates itself once running on pure derv. She said its showing 54mpg after the 140 mile trip home today which is way down on what it should show, although the actual fuel consumption seems to be fine.

Edited 29 April, 201214 yr by capriman