How accurate is your trip computer?

[Discotd5fan]

Hey guys,

Just wondering how accurate people's trip computer is in relation to Range and Ltrs/100km?

Mine is a 2000 4.0 S with the standard size tyres (255/65/R16), however the trip computer seems to be way out. When I bought the car the previous owner told me that the fuel gauge was slightly out, so that when I had 1/8 of a tank left it was empty. I have done two long trips (750km each) in the car now and have realized my average fuel consumption readout and fuel range via the message board are way out.

For example: My last tank I traveled 519km and put in 72.08ltrs. That works out to be 13.88 ltrs/100km (when you do the calculations), however the trip computer for the trip was reading 12.6 ltrs per 100 km. The trip computer was also telling me that I had a range of 380km left, however seeing there was only about 20 odd ltrs left in the tank there is no way that was possible.

Has anyone else encountered this problem? If so, is there a way of 'resetting' the system so it is correct? Or should I just add approx. 1.5ltrs to the average readout? I am more concerned about the range readout being correct as that is the most useful when doing outback trips.

Cheers

[Keithy P38]

Mine is pretty good. Usually around 0.2L/100km on 255/70/16 BFG KM2's.

I think you'll find it's got to do with the standard size tyres leaving an error between Kim's travelled and what the odometer/trip computer sees.

As I said in my cape trip update just now, my odometer was within 9km of the GPS kms over 3,300km just recently.

The easy fix? Taller tyres! The hard fix? Put a petentiometer in line on your speed feedback line to correct the error. You'll probably find you are traveling at 92ish kmh when your speedo says 100kmh at the moment.

Cheers
Keithy

[p38arover]

You'll probably find you are traveling at 92ish kmh when your speedo says 100kmh at the moment.

My speedo is almost spot on (within a needle width) compared with several GPS units I've tried.

The three Subaru Foresters we've owned have read 118 on the speedo at 110 on the GPS.

[FANTOM P38]

Along similar lines I have issue with accuracy of fuel gauge. I had problem wher gauge would not read properly i.e not move higher than 3/4 or lower than 1/4 tank.
I have since replaced fuel sender/pump on tank with new unit and also swapped out dash gauges and still seem to have problem in that don't get full tank.
Can anyone assist re any other component that may be causing this problem? I'm sure this will also be affecting my range calculations also.

[TheTree]

Hi

I too used a couple of GPS units and verified my speedo is very accurate.

I assume that means the trip computer will be as well

Steve

[benji]

The speedo can be out, but the odo could be correct. Mine says 96when im doing 100, yet the odo is spot on. Occasionally the speedo drops down to 80 though, so somethings amiss there.

Im guessing the speed signal to the becm and instrument cluster is correct but the speedo guage is dodgy.

Worn or dirty injectors, bad fuel pressure or larger tires will effect dash fuel consumption figures; as the ecu measures injector opening times over distance, but as you've said Kiethy it gets confused in lowrange slow going, posdibly as idling around lots uses infinite litres per 100km. And a dodgy fuel sender unit will stuff up the range left.

[hoges5]

was just looking at other threads and came across this one. Funny as I was trying to figure out the vague nature of the trip compute over the last long weekend.
On a simply freeway trip over about 250kms, I was really impressed as the 4.6l V8 was not using much fuel.
I had travelled about 30 or 40 ks and range estimation had not moved.
Then all 13 years of craziness set in as the range suddenly dropped 58kms inside of 2 minutes and then slowly rose again.
No change in speed, tires, driver or elevation......gotta love the Rangie keeping me entertained on long drives!

The fuel gauge seems fairly accurate, but the range estimator is way off - it cut out with about a third of a tank left...;)

[mtb_gary]

was just looking at other threads and came across this one. Funny as I was trying to figure out the vague nature of the trip compute over the last long weekend.
On a simply freeway trip over about 250kms, I was really impressed as the 4.6l V8 was not using much fuel.
I had travelled about 30 or 40 ks and range estimation had not moved.
Then all 13 years of craziness set in as the range suddenly dropped 58kms inside of 2 minutes and then slowly rose again.
No change in speed, tires, driver or elevation......gotta love the Rangie keeping me entertained on long drives!

The fuel gauge seems fairly accurate, but the range estimator is way off - it cut out with about a third of a tank left...;)

You've just gotta love the p38 RR :D. Compared to modern electronics and the on board diagnostics the p38 is somewhat less accurate ;). But as you said Hoges that's your on board entertainment unit ;). That and listening for noises, and then thinking the worst!

Gary

[Hoges]

What:wasntme:I have a doppelganger on this forum?:eek: