I am a fairly new owner of a R53 06 . After reading about resetting the computer to relearn my driving habits I did and my gas milage has plummeted to around 21mpg in city?!?

Anyone else have this problem or suggestions?

 

Are you noting the reduced MPG from manually calculating your fillups, or via the on board computer's average?

 

So far it has only been with the onboard computer. I know I need to do a manual test. Mainly going on the fact that I have averaged under 300 miles for a full tank of gas compared to 350+ when I first picked up the car.

 

My old '02 MCS was overly optimistic on estimated MPG. My current '06 MCS is somewhat pessimistic about estimated MPG. Best to calculate manually yourself.

 

When a computer is reset, the fuel trims, etc are relearned by the computer....
I have been told it takes about 50 miles to relearn...
Please remember, during the summer you are also using the ac more, and the fuel is warm...hense less dense...so a gallon might not have the same power (by a small %). Some states have actually debated making pumps compensate for pumped fuel temp, but most, usually due to cost, have ended up with stickers stating fuel is sold by volume...

 

Zippy makes a good point about the fuel. But it is actually the air that makes the difference. The air is warmer so it can hold more gas particles, you engine has to work harder to produce the same about of power in comparison to the winter months.

1) check your driving style, drive like you at 80 yrs old and see what happens to the MPG 2) give it a few more miles to finish its calculation period.

 

Warmer air is less dense....
So a given motor makes less power with hot air...
And the computer also uses a overly rich mixture as one coping technique to prevent detonation/pinging due to hot intake temps and/or other issues than may trigger the nick sensor....

 

Wow, thanks for all the great replys! For living in Texas a) I do use the ac with every trip though the temp has been ruffly the same since I picked up the car. 98-103 averages now and around 92-95 when I bought the car a couple of months ago.

Thought it could be driving style myself, though to save gas I do drive as though I'm 80 except to catch up to other mini drivers that blast past me since doing these tests.

I have a long drive to make tomorrow so I will see how the highway driving is fairing and I'm make sure to crunch the hard numbers. Also, give the computer well over the 50mile break in period.

Thanks!

 

well, calculated my mpg on paper. 2/3 of the miles were highway and the other 1/3 city. Was at 24mpg

 

I experienced this too. I reset the ECM after two or three months of having the Mini. On the highway I used to get at least 7.5 L/100 KM (31 MPG), in sixth at 105 KM/H I could find 6 L/100 KM (39.2 MPG). After the reset, I average 9 L/100 KM (26 MPG) per tank. Highway gives around 8 L/100 KM (29 MPG) even when doing 105 KM/H in sixth.

All of these were calculated by my ScanGaugeII and the tank was manually calculated to make sure the ScanGauge was accurate. It's hard to tell if there is a difference in power between the two, but I was able to spin the tires on take-off before resetting the computer, obviously with DSC turned off.

Immediately after the reset, yes I did notice a difference, but I'm not sure if it was worth it. My tanks lost 6 MPG after the reset. I'm going to try to baby it after I reset it tomorrow to see if I can get that mileage back. I'll be sure to report back.

CliffNotes...

Before Reset
HWY: 7.1 L/100 KM (33 MPG)
CITY: 8.3 L/100 KM (28 MPG)
TANK: 7.5 L/100 KM (31 MPG)

After Reset
HWY: 8.2 L/100 KM (28 MPG)
CITY: 11 L/100 KM (21 MPG)
TANK: 9.1 L/100 KM (26 MPG)