toddjb

I recently disconnected my battery while doing some speaker upgrades and when I drove home I noticed my mpg display was showing about 4 mpg more than normal.

Since I purchased the Jeep in Dec. I was getting a pretty consistent 14ish mpg on the display. I wasn't jazzed about it but I didn't really mind. We all know we don't buy Jeeps for good mileage.

Anyway, since the speaker upgrade I have driven as normal for about 4 days and my readout still shows mid 17s for mpg.

I am pretty excited.

What do you guys think? something in the computer was glitching on me previous to the battery being disconnected perhaps? Or maybe, just maybe, KICKER speakers are good for mileage!!

little_cornball

Don't trust the computer. Get yourself a good pocket calculator. IMHO

GJeep

Which Kicker model did you install that did this? I'll get them too...

JK-Ford

The computer starts re-learning after it is powered down for so long. Give it some time to accumulate data.

ronjenx

Yes.
When you disconnected the battery, your mpg calculations started over. The bit of driving since you did that may be different from the driving that was in the computer's history.
At any rate, the time/distance since the reset is way too short to feel good about it.

toddjb

You guys are a bunch of Debbie Downers.

haha

ronjenx

I prefer Objective Observers.

GJeep

I can expect the 'Miles left' to be calculated according the computers' past 'experience' (although that's not needed because it has the average MPG), but not the actual MPG.
Why would disconnecting the battery be any different from manually resetting the MPG ?
The display quickly settles to the current MPG average.
This average is calculated from the actual fuel consumption and Miles traveled. It is not based on future driving style.
(Its accuracy or proper calibration is another story.)

If it was not reset for some time and accumulated a long-term average, than a few days' driving may show a different average than the long-term average -- because there really is a true difference.

Still, I'd give those speakers a chance... LOL

yo_marc

Not sure how the Jeeps react - but certain (most?)(all?) ECU's will need to re-learn fuel trims after the ECU has been disconnected for so long - I think that's what JK-Ford was getting at.

Until the fuel trims are dialed in - you may get higher/lower mileage than normal.

toddjb

I had played around with this mpg display many times in the past. Resetting it before a highway trip to see what I get on the highway or just resetting it in town for one reason or another.

Every time I reset in town it would be 18 or so as I was driving at 45 without stopping, then it would just start tanking as I stopped for lights, corners, stop signs, etc. by the end of the day it would always be back to around 14.1 or 13.9.

It's not acting that way this time. Maybe it will go back down over time but this is new for now.