horrible gas mileage

[lga714]

I have an S50/ZF/3.25 and with some spirited driving and mostly cruising on the highway at 3500rpms I get about 8mpg...



It only seems to be getting worse too. I'm concerned because I just got a job where I'd be driving all over the place day in day out. What am I looking at here?

[straight6pwr]

I have an S50/ZF/3.25 and with some spirited driving and mostly cruising on the highway at 3500rpms I get about 8mpg...



It only seems to be getting worse too. I'm concerned because I just got a job where I'd be driving all over the place day in day out. What am I looking at here?

concerned because something is wrong with your motor.

[Sagaris]

So many factors come into play
Underinflated tires
bad wheel bearings
dragging brakes
bad O2 sensor
bad coolant temp sensor
fuel leak

[gregslow318i]

So many factors come into play
Underinflated tires
bad wheel bearings
dragging brakes
bad O2 sensor
bad coolant temp sensor
fuel leak

bad tune
bad maf

and on and on and on.....

[LowR3V'in]

cruising on the highway at 3500rpms I get about 8mpg...

Maybe stop cruising at 90mph.

[lga714]

Damn I could spend a grand trying to tackle this problem.

[hoveringuy]

Damn I could spend a grand trying to tackle this problem.

No. Start with the simple things. What do your spark plugs look like?

Go on a decent drive, park without idling and read the plugs.

Will the car coast decently in neutral?

My guess is the MAF.

[dsobering47]

Do you have access to a fuel pressure gauge? Maybe your FPR is bad and overfueling...

[lga714]

No. Start with the simple things. What do your spark plugs look like?

Go on a decent drive, park without idling and read the plugs.

Will the car coast decently in neutral?

My guess is the MAF.

Well the head was rebuilt with all new plugs with less than a 1000 miles on them. I'll take a look at all of that tomorrow. I have a spare MAF that I'll swap in the meantime. Could a bad TPS be the culprit?

[lga714]

Also, I should note that the gauge fluctuates during the drive. For instance, today I started it up and it was just under 1/4 tank, as I drove a few blocks the gauge read at about 1/3 tank. By the time I was done driving (~25 miles) I was near empty.

[Dominic49]

i get better than that (sometimes) in the turbo s50 race car

[lga714]

thank you Dominic lol

[ck_taft325is]

I'm right at 23mpg with mostly 50mph roads, S50/ZF320/S3.46...

Definately check the MAF.

[e46s54dr]

I'm not exactly sure on how the on board computer calculates mpg but my e30 was guzzling gas like a beast. I mean an insatiable beast. Turned out my fuel line was leaking from both the fuel rail and the fuel filter. I ended up replacing the whole system of lines. Not too hard or expensive if that's your case.

[lga714]

Hah my OBC is worthless so I reset my trip odometer each time I fill up then divide by whatever amount of gallons I used. I haven't seen a drop of anything on my parking spot so I've ruled out leaks.

Will update the thread tomorrow.