Trip Computer Mpg

promethian · 06-30-2008, 01:09 PM

Does anyone know how the trip computer measures mpg....?

The mileage part is obvious but how exactly does the trip computer measure the fuel the fuel part?

Alarmin · 06-30-2008, 02:04 PM

Just a guess,

But I think the amount of fuel used is measured therefore the calculation can be done.

If you set your trip computer to inst, then drive with foot down, the fuel consumption drops dramatically.

Ease of on the pedal and it goes to 99.9 mpg.

If any one out there knows where the metering takes place, let us all know.

Bunker · 06-30-2008, 02:11 PM

Quote:

Originally Posted by Alarmin

Just a guess,

But I think the amount of fuel used is measured therefore the calculation can be done.

If you set your trip computer to inst, then drive with foot down, the fuel consumption drops dramatically.

Ease of on the pedal and it goes to 99.9 mpg.

If any one out there knows where the metering takes place, let us all know.

You sure that you want to know?

See the attached

Alarmin · 06-30-2008, 02:41 PM

Cheers Bunker,

Clear as mud.

Bunker · 06-30-2008, 02:42 PM

Quote:

Originally Posted by Alarmin

Cheers Bunker,

Clear as mud.

And you're better placed than most to understand it

promethian · 06-30-2008, 03:37 PM

Thanks Bunker... just what I needed..... so it uses the injection pulses X 80uL

promethian · 07-01-2008, 01:55 PM

Oh by the way... if you wondered why I was asking the question it is for this reason.

I have bought a piggyback unit that modifies the fuel mapping and thus the pulses from the ECU. The unit has 10 different maps from economy to performance.

As these pulses are modified the MPG reading I now get displayed from the Trip computer is now inaccurate because as Bunker kindly provided me the formula for the calculation above.

I'm doing trials on the unit at the moment. The performance settings are stunning and the engine feels to have a much higher torque and smoother rage( I mean range..lol|) from 1500-3500 rpm.

But most importantly I want to try out the economy settings and thus obviously need to do brim to brim measurements.

PS this piggyback unit is only £150

tim_p · 07-01-2008, 02:07 PM

shirley, if you test map 1, then map 10, all the rest are somwhere in between. Howabout if you choose the economy map and thrash the hell out of it?

promethian · 07-01-2008, 02:22 PM

Wish it were that simple...lol The maps are in 4 bands and change either low end, high end or both in three maps for each band of low med and high. The other map is low/low for economy.

Anyways who the hell can afford to thrash the hell out of their motors in this current climate...lol... I always picture a line from my wallet to the accelerator pedal every time I put my foot down... soon curbs the enthusiasm... which is a pity.

tim_p · 07-01-2008, 02:44 PM

The cee'd does seem very variable, certainly more so than my other two drives / rides. I use the Merc most weeks for a couple of days and despite several good, but short thrashes on the drive into work it usually manages 30+mpg. Do the same on the cee'd and it can easily lose 15-20% of its economy.