The air filter is of course quite important, as is your driving habit. If
you are getting 25 at a steady 55 with your larger tires, you are not so far
off. My car has a fresh rebuilt engine. Try getting a two way average at a
steady speed, with the cruise control or you holding the throttle steady on
a flat, level road. Your city is probably a lot more city like than my
city (high desert sparsely settled area.)
If your car is running as well as you say, I'd advise you to be happy with
it. There aren't many 4500 pound luxury cars running around that can get 25
MPG under any conditions!
Is the original exhaust system still on the car? O2 sensors are cheap and
easy to change. If it has been on the car more than 50,000 miles it is due
anyway. Is the initial ignition timing set to 12 BTC, and are you running
premium fuel?
Dick Benjamin
----- Original Message -----
From: "William" <mopar@xxxxxxxxxxxxxxxxxx>
To: <mailing-list@xxxxxxxxxxxxxxxx>
Sent: Thursday, May 02, 2002 9:22 AM
Subject: Re: IML: 83 EFi spark plugs, MPG update...
> Wow, it sounds like I have some work left to do! I am lucky to get an
> indicated 24-25mpg at 55mph. My average has been about 15mpg for city
> driving, but I do have a bit of a heavy foot. Are there any main causes of
> poor fuel economy specific to the EFI cars? I thought the plugs might be
the
> issue, but although it runs much better, fuel economy doesn't appear to
have
> jumped dramatically. All the old plugs I removed were a nice tan colour,
so
> I am not concerned about internal engine condition or oil fouling. Maybe a
> vacuum leak? Leaking fuel in HSA? How about an O2 sensor? It runs so very
> nice that I don't see it being something major. Oh, and I suppose I should
> change the air filter...
> William
>
>
>
> ----- Original Message -----
> From: "Dick Benjamin" <dickb@xxxxxxxxx>
> To: <mailing-list@xxxxxxxxxxxxxxxx>
> Sent: Friday, May 02, 2003 10:06 AM
> Subject: Re: IML: 83 EFi spark plugs, MPG update...
>
>
> > Yes, the original tire size was 205/75/R15, as the door sticker states.
> If
> > you use the original tire, you will get better acceleration, and better
> > "indicated" fuel mileage, but lower actual fuel mileage. If you use the
> > larger tires, you will get longer tire life, better actual fuel mileage,
> and
> > slightly poorer acceleration. I have run both sizes on the 4 '81-82's I
> > have owned, and have decided that next time I "retire", I will go back
to
> > the original size, although I certainly won't do it until I wear out the
> > 215/75/R15 Michelins that are on it now - which will probably take as
long
> > as I am able to drive.
> >
> > According to the dash readout, I am getting about 28 MPG at a steady
> > (indicated) 55 MPH on a flat,level road with no headwind or tail wind.
If
> I
> > were running the original tire size, this would read about 10% higher
due
> to
> > the odometer correction, plus some additional correction because I would
> be
> > going through air resistance about 10% slower, so I'd estimate the
readout
> > would be 32 MPG or so.
> >
> > According to careful measurements on our most common trip, which just
> > happens to be almost exactly 500 miles (Temecula California to Lake
Tahoe
> > California) I get about 25 MPG average on the trip. I drive between 75
> and
> > 80 on the trip about 2/3 of the way, the rest is mountain driving on
windy
> > roads, so I probably average about 60.
> >
> > This number is the result of dividing the known actual mileage by the
> total
> > gas consumed, determined by a brim full fill-up before and after each
> trip.
> > Note that this 1000 mile round trip involves about 30% driving in very
> high
> > altitudes (8000-9000 feet) and some very long hills (11 mile, 6% grades
> in
> > two places). We make this trip once or twice per year, and have every
> year
> > since I have owned the current '81 (since 1987), and the results are
quite
> > consistent.
> >
> > For around town use, I average about 18 MPG (ours is not a very
congested
> > town, by eastern standards!)
> >
> > For those who question the wisdom of taking these cars on trips, I can
> > report that we have driven these cars all this time without ever having
to
> > call the man with the hook to get us home (although a failing fuel pump
> made
> > me worry a bit on a trip to Boise one time in 1989, but we did make it
> under
> > our own power!).
> >
> > Dick Benjamin
>
>
>
>
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