Reply With Quotehole in the tank?Originally Posted by diamond777
Big Time Poster
big drop off in mpg
91 535i auto 209k runs great -but the mpg went from 21 all the time to 16-18 after a battery change-any ideas????
Green Beret Special Ops
hole in the tank?
95 E34 530I V2.37
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Those who make peaceful revolution impossible will make violent revolution inevitable.
John F. Kennedy
3 Grand Master
Filled up with E10
mine dropped after a few tanks of that crap
Vee ave vays of dealing vid your kind...........
Major Contributor
The usual culprits are O2 sensor and AFM. The battery change might be a concidence, exacerbated by resetting adaptation.
Big, Big Time Poster
are you doing mileage by the computer/tripmeter or your actual odometer mileage?
if dojng the first I'll bet you have to recalibrate the puter
3 Grand Master
Could just be
Since you'v e disconnected the battery recently, the OBC has a shorter duration and mileage data to avergae by.
Just for fun reset AVG 2 and see how quickly your AVG MPG changes with a few stop lights and coasting down a hill.
I know the first few hours after a disconnect, the AVG is quite sensitive to changes in driving conditions.
Last edited by Blitzkrieg Bob; 05-03-2006 at 11:48 AM.
Vee ave vays of dealing vid your kind...........
4 Grand Master
Ethanol? Will reduce 10%...
Grand Master
actually a 10% ethanol blend reduces mileage by about 20%.
I would think the ecu just needs to relearn its timing adjustments again over a few dozen "warm" miles.
Major Contributor
Who's spiking with 10% ethanol now?
Big, Big Time Poster
Not quite. MPG is directly proportional to the heating value of the fuel. Gasoline is ~115,000 btu/gal, ethanol is ~77,000 btu/gal.
(1) gallon E10 is .9*115,000 + .1* 77,000 = 111,200 btu/gal
111,200/115,000 = 96.7%
10% ethanol reduces mpg about 3.3%
Paul Shovestul
.....Got to keep the loonies on the paath.
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