318is (M42): mpg, what are you getting?

[dtdub]

So I picked up a '91 318is as a daily driver, opting for the 4-banger as a more fuel efficient option. Since I've had it, I've done a fairly comprehensive tune-up, including full synthetic engine/trany/diff oil change, plugs, rotors/pads, wheels/tires, H&R sports and bushings galore.

I'm still only pulling down about 26mpg which seems very low for a 1.8 16v (esp since I'm getting 24 in my WRX). I talked to a buddy with a e36 318ti (M42?); he says he's getting ~34mpg.

Am I missing something? is 26mpg typical, or am I missing something? :(

[devonjordan]

I get abot 350 miles to a tank, driving like a dumbass most of the time.

[drift]

whats the actual mileage of the car?

compression and leak-down test?

old O2 sensor?

wheels/tires dimension?

city/highway ?

AT / manual (iS = manual)?

[LovableSheep]

I get between 27 and 30, mixed city/highway driving.

[nando]

I got a pretty steady 29mpg freeway/city with a beat to shit 250,000 mile 318is.

[KenC]

I get about 26 combined... mine has 285k now... not the most efficient machine. Probably going to put in a new O2 sensor soon.

[dtdub]

My 318 only has 92k miles so it's not a clapped out motor. I have mostly a highway commute with no traffic, so I'm cruising at 60-75mph. Right now I have 205/50/15 tires on the car (VW BBS RX wheels). ...and, of course, a manual gearbox. I took a few long highway only trips in it and still barely got to 28mpg.

A bad 02 sensor is possible; I haven't checked that yet. I just had the car aligned, so that shouldn't be a problem.

The fuel pump is making a bit of noise (I haven't gotten around to replacing it yet). The fuel filter was also just replaced.

[seiferguy]

My 318is has gotten as low as 26mpg, and I've gotten it to 32mpg as well, though I've gotten it that high only once. It's currently got 248k on it, but the engine has about 129k itself. I get around 30 if I drive nicely and don't push the engine.

I dunno what could be causing yours to be lower, though =/

[dtdub]

lt sounds like I am riding on the low end of fuel economy if the best I can get is 26mpg. Lame.

The only thing I can think of at this point is the fuel pump noises are indicative of too high/too low fuel pressure in the rail, and the engine is not compensating correctly. That or the O2 sensor is bad.

[drift]

Do a compression/leak-down test ( who knows...) ?
Check see how much currents the coil delivers through the plug wires ?
Spark plugs rating?
Oil ( engine, trans) viscosity?
Coolant temp sensor ?
AFM sensor ?
O2 sensor reading ?
Air filter ( http://www.bolhuijo.com/airflowtest/ ) ?
Trunk fully loaded, stereo boom box, sound deadening ?

[BUDNUNTA]

Im getting about 28 now with 225/50/15s on K1s
When I had weaves with 195/60/14s and summer gas I could get 32.
Winter gas always seems to yeild less mileage around here?
My car is in good running order, good compression, new o2 sensor. Plus I have a Metric mechanic exhaust with a Jim C chip.
Dont know if that helps mileage.



Hunter

[nando]

winter gas has more ethanol, and ethanol causes a drop in MPG.

[dtdub]

Do a compression/leak-down test ( who knows...) ?
Check see how much currents the coil delivers through the plug wires ?
Spark plugs rating?
Oil ( engine, trans) viscosity?
Coolant temp sensor ?
AFM sensor ?
O2 sensor reading ?
Air filter ( http://www.bolhuijo.com/airflowtest/ ) ?
Trunk fully loaded, stereo boom box, sound deadening ?

*I've never heard of checking the coil current... how do you do that? They prol could use a replacing. Have people had good luck with Magnecor, others?
*I got replacement OEM plugs from Pelicanparts.com
*Just changed the oils:
Engine=Mobile1 15w50 full synthetic
Trans=redline MT-90
Diff=redline 75w90
*Only the factory stereo, even the spare tire has been removed.
*new K&N air filter
*The coolant sensor seems to read ok, but it does stay around the 1/4 mark most all the time? Should it read higher? Does it think it is still in warmup? Tips on checking it?
*Tips on how to check the AMF sensor?

Thanks for the good feedback

[ian e30 318is]

30 freeway/25 in town

[KevyWevy]

30mpg on mostly freeway ~70mph... but my mpg gauge was saying a little under 40. anybody know how accurate these are?