Strange IPK figures
 

Just seen ZTT post about mpg on IPK computer. Don't often reset mine but do check figures quite frequently. In past week without being reset the range figure has been well overstated, yesterday it showed 408 miles, and 12 miles later having been rest twice dropped to just 93 miles, at a point where on the fual guage I would normally expect a low fuel light.

Plenums are dry and clear due to regular checks as precaution, not done a battery reset but will watch situation after next 2 refuels to see it corrects itself, unless anyone can throw some light onto this.
Chips

Moved to technical help forum:}

If you want the OBD range/mpg display to be anywhere near realistic never reset it.

For more detail on this, read my latest edit of the Diagnostic Mode routines.

Clicky: http://www.the75andztclub.co.uk/foru...ighlight=ipkdm

The Range display depends on the accuracy of the data used in Section 20.

Hi T-Cut, thanks for that, as I said it is not usually reset and often consulted, but when the range gives a figure of 408 miles with under 1/4 tank clearly a reset is called for. After doing that several times last night a 15-mile mixed roads trip was giving a realistic figure (68 miles) with 35.2 mpg, reset again just before refueling then gave 32.8 mpg over last 2 miles, range figure (152 miles) appears correct for amount of fuel filled (£20.00) at Tesco.
Figures before range problem and over previous 6-months or so were showing an average of 29.4mpg.
Chips

Using reset while driving can produce almost any result you want. The first calculation is based on the instantaneous data as you reset it. That gets 'averaged' out as time and driving conditions change. Here's an example.

http://i5.photobucket.com/albums/y19...de/7mpg004.jpg

What accuracy would the range readout have at this point?

TC

Hi T-Cut, the whole point was over past few days as road mileage increased and fuel level decreased, the range was going up not down as it normally would. End of last month full tank refill, last week part refill £20.00 then range figure became unrealistic.

Figures of yesterday and today are better, taking into account amount of fuel added to that remaining new figures appear correct. Hopefully resetting has 'started all averages again' and while it is never 100% accurate over a short period for mpg and range available, it does look rather like it's the 'base' figures are about as expected.
Chips

TBH I thought the range figure was the one that could not be reset :shrug:

And the fact that the range figure can increase is not suprising - say you have spent the day in traffic and MPG will be pretty terrible ( mines a V6). You then drive home on a M Way at a steady 70 and MPG will improve. Therefore the range at the then current MPG could increase.

However there is a known glitch in some dashboard displays whereby the range figure can show huge figures - I have seen 900 plus miles on a couple of occasions on mine. Always cured, at least on mine, by putting some more fuel in the tank which forces the computer to recalculate to a more sensible figure .

hth

Well pretty much spot on for a V8 going up a steep hill! :laughing2::driving::laughing2:

Mike

Hi David, I thought that too, but last night due to fantastically high range figure I did reset first the mileage trip, then range and mpg, trip went 0.00 while the others rest with --- -- then filled up, well £20.00 worth and all figures 2-miles later were as you would expect.
Chips

The range figure as far as I know is totally unrelated to the other readouts, i.e. its reading is not directly affected by their readings, and as has been said cannot be reset. All its reading is based on is the last few minutes driving.