Re: Lousy fuel economy on '91 200TQW; advice, please.

["Fred Munro" <munrof@isys.ca>]

Hi Jim;

    Your city mileage is not far off what I was getting with my '91 200q -
mine was around 13-14 mpUSg. Over 5 years, the car averaged 10 litres/100km
(23.5 mgUSg) with a mix of 80% highway/20% city driving.

Fred Munro
'94 S4  94k km

----- Original Message -----
From: "James Desveaux" <desveaux@ucla.edu>
To: <quattro@audifans.com>
Sent: Saturday, December 11, 1999 5:13 PM
Subject: Lousy fuel economy on '91 200TQW; advice, please.


> I've probably run this across the list before, but let me try again.
>
> I've got a car that runs splendidly and it's very reliable, with 105k.
> Since  buying it about 20 months ago, I've carefully put money into it,
and
> all the regular maintenance items are taken care of.
>
> But here's what's puzzling me.  The car gets absolutely miserable gas
> mileage around town.  Mind you, I'm not expecting a lot, but it's probably
> getting about 13mpg if I stick to city driving.  On the freeway, of
course,
> it's much better, and I've gotten in the mid-20s on the freeway.  Around
> town, I drive it pretty reasonably, and I'm not putting my foot into it.
>
> Here's some further info:
>
> 1. It's got an IA Stage II chip
> 2. I had some mild  bucking at high boost several months ago, and
replaced
> a couple of vacuum lines, and that problem is gone.
> 3. I replaced the O2 sensor this past spring, with the generic Bosch unit
> from a Ford Probe through the Parts Connection.  Thinking there might be a
> problem with the new O2, I checked the voltage, and the range is .3 to .9
> volts (or 3-9, can't remember which).  A friend with a shop in the Bay
Area
> tested it and his gauged showed the average voltage at the O2 to be .59
(or
> is it, 5.9, I forget).  He said it was a bit high, but within range.  The
> car idles fine.  Could this be a problem?
>
> 4. I've checked pretty much all the sensors per the Bentley, and they read
> okay.
>
> 5. Scott Mockrey said a thermostat that causes engine temp to run cool
> could be a contributing factor.  I  bought a new one and I suppose I
should
> try installing it and see what happens.
>
> 6. I generally use 92 octane, and occasionally run Techron through it.
>
> 7. Three months ago or so, I put it on an emissions tester, and it was
very
> clean.  I even ran the probe into the pipe off the headpipe before the
> converters, and it would've passed (I think).
>
> 8. Some time back, I checked the plugs and they looked okay.  I replaced
> them a year ago with OEM.  The resistances on the plug wirers all checked
> out.  And I'm not getting any codes.
>
> 9. Could there be a fuel pressure regulator problem and still pass smog?
It
> has a new vacuum hose to it.
>
> 10. I am checking fuel economy according to how much the car actually
uses,
> not relying on the computer (though it's fairly accurate).  With the last
> tank, including close to 100 miles of freeway driving, I averaged exactly
> 16 mpg.  This doesn't seem right.
>
> Any BTDT?  Advice?
>
> TIA
>
> - Jim
>