[s-cars] Cold weather and lousy fuel mileage

[Mark Rivera]

Sorry I can't help, but you're in much better shape than I.  My bone-stock
102K mile 93' S4 got 12.75mpg last fillup, all in-town driving, and I don't
exactly drive to get good mileage.  Still, I would expect much better.

I think 16mpg is the best I've ever gotten in my 4 months of ownership.

Mark

-----Original Message-----
From: s-car-list-bounces at audifans.com
[mailto:s-car-list-bounces at audifans.com]On Behalf Of Stott Hare
Sent: Friday, March 09, 2007 1:13 PM
To: s-car-list at audifans.com
Subject: [s-cars] Cold weather and lousy fuel mileage


Weather here in the Northeast has had the temps hovering around 0*F, and my
fuel mileage has gone straight to the toilet.

Nice weather (40*F>) and 95% highway I can pull 21mpg and around 400 per
tank.  Cold weather and 85% highway and I watch my mileage plummet to 16mpg
and maybe 250-300 miles a tank.  Watching the TDS1 when the outside air temp
is an indicated 0 - 15*F  shows an intake air temp ~20-25* warmer.

Patient is a 95 S6A with 252k on the clock.  Still stock.  Receives routine
maintenance.  She plugs, oxy sensor and fuel filter were done around 204k so
they could be considered due, but I would expect that to cause decreases
across the board, not temp specific.  Coolant temp is rock solid at the
first fat bar (~10 o'clock).  Multi-function temp sender was done at 204k.
The HVAC temp sensor in the coolant line between block and heater core
replaced about 230k.  No CEL or codes.

My prior experience with the CIS cars didn't yield such temp sensitive
performance, if you had the car tuned right and all sensors working.  Is
this something particular to the Motronic / hot-wire MAF systems?  Is the
incoming air so cold that the hot wire isn't?  I don't have my mixture gauge
in at the moment, but I suppose I will hook it up this weekend and watch
mixture over the next week.  When I had it hooked up in normal temps
previously (within 5k), mixture behaved as expected at idle and cruise, on
throttle and off.

This just the way things are? or is this an indication of a (temp) sender or
something that is begging for replacement.

Thanks!
 -Stott
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