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Consumption function

Printed From: Bavarian-Board.co.uk - BMW Owners Discussion Forum
Category: Technical & Model Specific Forums
Forum Name: BMW 6 Series
Forum Discription: This forum will deal with any issues on the BMW 6 Series (E24, E63 & E64)
URL: http://www.bavarian-board.co.uk/forum_posts.asp?TID=32900
Printed Date: 04-May-2024 at 09:20


Topic: Consumption function
Posted By: phb10186
Subject: Consumption function
Date Posted: 21-August-2006 at 10:01

Could somebody please explain how each of the 2 fuel-o-meters work, and their relative accuracy. I have the updated trip computer from '84 on.

Where do each of these take their info from, and does the computer regard enriched running when the car is cold e.t.c e.t.c?

I have always thought that the one below the tachometer is not really worth looking at unless you are cruising at a sensible speed.



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1985 635 CSI with Style 134's
1998 Z3 2.8i


Replies:
Posted By: AndyS
Date Posted: 21-August-2006 at 10:53
IIRC the computer takes a reading every 30 metres, calculates & updates the reading.

The Swing-o-meter is neither use nor ornament as far as I'm concerned. I'd rather have the oil temp gauge from the M cars.



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AndyS
Live each day as if it's your last - one day it will be.

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Posted By: phb10186
Date Posted: 21-August-2006 at 12:07
but where is it taking the reading from, and what is it measuring?

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1985 635 CSI with Style 134's
1998 Z3 2.8i

Posted By: m3Cecotto
Date Posted: 24-August-2006 at 10:01

Originally posted by phb10186 phb10186 wrote:

but where is it taking the reading from, and what is it measuring?

Induction vacuum I believe, but how valuable that is in terms of measuring fuel economy is beyond my ken.



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1981 E23 735i
1989 E30 325i Motorsport Cabrio
1989 E24 635CSi Motorsport Edition

http://www.bavarianretro.com" rel="nofollow - Bavarian Retro Cars

Posted By: Brucey
Date Posted: 24-August-2006 at 19:07
Originally posted by m3Cecotto m3Cecotto wrote:

Originally posted by phb10186 phb10186 wrote:

but where is it taking the reading from, and what is it measuring?

Induction vacuum I believe, but how valuable that is in terms of measuring fuel economy is beyond my ken.

it is also related to road speed/ engine rpm as well;

induction vacuum is related to throttle opeing and hence fuel consumption BUT only if the engine is at constant temperature. Thus the readings are only evenremotely accurate if your engine is fully warm and your injection system is working properly.

I believe the OBC reads injector pulses; not sure if it reads the cold start injector as well or not.

cheers

  



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~~~~~~~ Brucey   ~~~~~~


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