Quote:
|
Originally Posted by UFO
Either the problem is the fuel consumption calculation at idle is too low, or the fuel consumption under acceleration is calculated too high
|
If your real tank was LOWER than your calculated one, it could be that the opposite the case - idle may be too high and acceleration calculated as too low ?
Do you have a link for the 0.1GPH idle figure ? I have a 1.9 TDI and mine is measuring 0.12-0.14 GPH - I have configured it as a 1.4 and adjusted 50% of the difference on each tank - my last one was 1.5% out. I have not yet had a 100% exact match but I accept anything under 3% as being inside a margin of error - things like temp when filling up, slope of the car, my ability to 'vent' enough and so on. Plus my tank to tank is not consistent driving - speed, temp and so on. It can't be as a tank for me lasts 3-5 weeks.
I mainly use the SG2 figure to monitor instant MPG - e.g. keeping my instant MPG above my average, as well as other figures such as coolant (grill blocked), MAP and so on.
As for P&G I didn't notice much of a difference in using vs not on my TDI - the difference was within my 3% difference and on one tank better and on one worse for P&G than a non-P&G tank. My tanks last too long to experiment with different speeds really, I could get better results if I did more miles.
My best result has been with cutting out idle whenever I can. I have, for example, switched one part of my route to actually go for a portion which is stop-start vs crawl - I can stop the engine in the stop part but not in the crawl. My last tank gained 8% on this change.
Mine is a manual but I would think that at a stop light you engine is not only idling but also pushing against the torque converter and so your idle GPH I would think is higher.