Folks,

Is it normal for 3rd gens to have poor fuel consumption after resetting the ECU? I used to get 10.3l/100km and 650km to the tank as indicated by the trip computer (usually only ran it to 600 or so.) After disconnecting the battery while working on it a few weeks ago, the trip was showing 11.0l/100km for the next tank, and got 600km. About 3 tankloads later, 140km into the tank and the trip is showing 10.1l/100km and a total range for the tankload of 680-690. Seems like the fuel consumption went crappy when I disconnected the battery, and has been getting slowly better with every tankload since..

Folks,

Is it normal for 3rd gens to have poor fuel consumption after resetting the ECU? I used to get 10.3l/100km and 650km to the tank as indicated by the trip computer (usually only ran it to 600 or so.) After disconnecting the battery while working on it a few weeks ago, the trip was showing 11.0l/100km for the next tank, and got 600km. About 3 tankloads later, 140km into the tank and the trip is showing 10.1l/100km and a total range for the tankload of 680-690. Seems like the fuel consumption went crappy when I disconnected the battery, and has been getting slowly better with every tankload since..
it will adjust but it depends on how you drive it.

Hello Zaphod,

By disconnecting the battery, you have reset your ECU. The ECU is now going through a re-learn process - starting from scratch. So your car has been running rich and slowly you’re seeing mileage results improve. This applies to DSMs with an ECU -1g, 2nd g. 3rd g.

A possible problem may be your O2 sensor, but not likely on what you described.

http://members.shaw.ca/costall/1000Q/ talks about this issue.

"Mileage in the 12-13 MPG (18-20 L/100 km) sometimes reflects a problem with the car. An old or failing oxygen sensor is a prime suspect, as this component senses the air/fuel mixture and, when bad (or even weak), can cause the ECU to supply more fuel than is necessary. According to Todd Day of Technomotive, even a slightly weak O2 sensor can knock 1-2 MPG off of the normal mileage. Since weak or dead oxygen sensors often do not trip the "Check Engine" light (see here for why), owners may not realize their O2 sensor is on the blink."

Hope this helps
TG

Folks,

Is it normal for 3rd gens to have poor fuel consumption after resetting the ECU? I used to get 10.3l/100km and 650km to the tank as indicated by the trip computer (usually only ran it to 600 or so.) After disconnecting the battery while working on it a few weeks ago, the trip was showing 11.0l/100km for the next tank, and got 600km. About 3 tankloads later, 140km into the tank and the trip is showing 10.1l/100km and a total range for the tankload of 680-690. Seems like the fuel consumption went crappy when I disconnected the battery, and has been getting slowly better with every tankload since..

Yes but your last figure (10.1) is better (less litres per 100klms) than the original figure (10.3) .... so what exactly is the problem? Things have settled down to an improvement.

Folks,

Is it normal for 3rd gens to have poor fuel consumption after resetting the ECU? I used to get 10.3l/100km and 650km to the tank as indicated by the trip computer (usually only ran it to 600 or so.) After disconnecting the battery while working on it a few weeks ago, the trip was showing 11.0l/100km for the next tank, and got 600km. About 3 tankloads later, 140km into the tank and the trip is showing 10.1l/100km and a total range for the tankload of 680-690. Seems like the fuel consumption went crappy when I disconnected the battery, and has been getting slowly better with every tankload since..

I had exactly the same problem after having a fuse blown and the ecu reset.. Fuel consuption jumped from 10L/100km to 15.. Mine gets down to 12 now, but its not the same :s

Thanks guys. Seems the answer to my question is "yes!"

I'm well aware resetting the ECU does affect things (spent the first week teaching my tippy how to shift gears!) but wasn't expecting the fuel usage to increase.


Yes but your last figure (10.1) is better (less litres per 100klms) than the original figure (10.3) .... so what exactly is the problem? Things have settled down to an improvement.

Yes, it seems to be ok now, but it took 3-4 tanks to sort itself out, during which time I was worried something else was wrong. :)


I had exactly the same problem after having a fuse blown and the ecu reset.. Fuel consuption jumped from 10L/100km to 15.. Mine gets down to 12 now, but its not the same :s

15? Wow, I'd have been freaking. So it's still not back to what it was before? That was quite a while ago wasn't it?

I had exactly the same problem after having a fuse blown and the ecu reset.. Fuel consuption jumped from 10L/100km to 15.. Mine gets down to 12 now, but its not the same :s

dear tayna have you reset the ecu after that little thing. that should fix it up.

but i when i do a ecu reset it does take a couple of tanks to get normal again or go on a freeway cruse to get it back to normal

dear tayna have you reset the ecu after that little thing. that should fix it up.

but i when i do a ecu reset it does take a couple of tanks to get normal again or go on a freeway cruse to get it back to normal

Havent done a full reset, no.. and It has been a while but I havent been doing too many long trips recently.. and a tank of fuel is lasting me 2 weeks instead of 1! so we will see.. give me a chance to get all this uni outta the way and il spend some more time on my car.. poor thing is feeling neglected at the moment..

I had a similar issue with fuel consumption when i had my kickdown to 3rd adjusted, took a couple of tanks to get back to normal. Don't know what ecu they (mitsi) reset, but was somewhere around the 14-15L/100km, now has settled down and average between 11-12.6L/100km.