re. factory instrumentation accuracy & mpg

Dan Simoes dans at
Sun Jan 26 20:20:35 EST 2003

ben swann wrote:
> Yes - peeve # 2 on the new aquisition of the '91 200 20v tq avant.  Has
> SJM chip with 2.5 bar pressure transducer AFAIK.

Lehmann stage 1 chip with 2.5 transducer.

> Gas mileage abysmal
> on the way home - 20MPG and no I was not easy on the gas and probably
> averageing over 70.  My '87 5000 tq would get an easy 28 mpg under the
> same conditions.  I thought Motronic was supposed to be superior at
> engine management, including economy, over CIS (CIS/motronic).

I thought I told you that I asked SJM about this and he correctly
diagnosed a failing tstat.  That's the reason the mpg is low.

> [Does anyone know how the driving computer arrives at the number it
> alls average MPG?  It definately has NOTHING to do with actual fuel
> flow!  Does it do it's calcs based upon stored parameters and ideal
> situation testing done at the factory?  Is there any way to recalibrate
> it?

The computer is balls on accurate at the moment.  Leave it alone.

Am I gonna have to get down there and bring this poor car back? :)

Spend some time on SJM's site and the list archives for 200q20v, and
you'll be well enlightened.

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