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Fuel consumption and on board computer

Hi Guys,

Decided to calculate my fuel consumption to see if the on board computer is accurate. Turns out that it is pretty off!

I reset the trip odometer (and Trip B) at every fill up and it is usually telling me that I am getting between 8.9 to 9.1 L/100. Today I did a fill up and then calculated the consumption based on liters in to KM driven and I calculated 9.76/100 (or 28.95 UK MPG, 24.11 US MPG).

I usually drive about 20km to work and back with approximately 10 min of that at 120-140 kph on the highway.

First, is it normal that my on board computer would under estimate the consumption by so much? Second, is this range normal for city combined?

Driving 2008 159 2.4 Q4

Also, from time to time I feel a lot of hesitation where the engine chokes. I usually keep my foot at the same level and don't lift.... it usually lasts for about 5 seconds then a few seconds pause then repeat. I assume this is the particle filter clearing, but is it "normal" that the engine chokes that bad? The first time it happened I was really shocked... it felt like it was running out of diesel and the turbo needle was jumping up and down.

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I haven’t done a brim to brim with my 2.4 but according to the km I drive with a certain amount of fuel it seems like my 2.4 underestimates the consumption about the same margin as yours.
I experienced a proper regen in moving traffic this morning and it was obvious that the motor sort of strains. I kept the rpm’s at 1500 moving at about 40kmh and when the regen stopped the boost went up to 0.4bar and the car started accelerating. While the regen was happening the boost stayed at 0bar at 1500rpm.
Don’t know if this helps but that is what I experienced.

My previous 1.9JTS were almost spot on with the onboard computers consumption compared to a brim to brim calculation.

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Triumph Trophy 1200 to counter the fuel prices.
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with my 2.4d the trip computer seems to underestimate the brim to brim calculation by about 1mpg
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Originally Posted by GroovyBoovy View Post
with my 2.4d the trip computer seems to underestimate the brim to brim calculation by about 1mpg
+1, with the brim-to-brim average being just under 35 mpg (2.4D Q4). If you do a lot of driving in town, or up and down hills (not wishing to draw any conclusions from your location ) then your figures of 28 mpg would be believable, although the turbo boost indicator bouncing up and down may be indicative of an issue
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