Jenny's ETA is getting 16mpg :(

[Joey Link]

So yeah, we have a problem. We knew the car was getting lousy mileage but finally calculated it a couple days ago. The gas light just came on and we put in 3.79 gallons. We drove exactly 63 miles (about 35% highway/65% city) before the gas light came on again. Calculated, this comes to an average of 16.62mpg, nearly half of what I hear some ETA owners getting. The car has 191k and seems to run well, but it's the only ETA I've driven so I can't say for sure. I replaced the air filter and I'm going to do the plugs today, but can't afford the wires yet. I'm also not sure the last time it had an oil change, so I may do that today as well.

What would you guys recommend to get her MPG up?

[E30 Wagen]

Perhaps you should try to clean the AFM. Probably doesnn't have much to do with it, but what octane do you run?

[Mike325]

To get better mileage, you are on the right track. By replacing the wear parts, like the plugs, this will help. I also suggest the following:

-Setting all the tires air pressures to around 32-35 psi
-changing the diff and trans oil (manual)
-changing the fuel filter
-possible alignment
-maybe the o2 sensor

Also, check to see if the car can roll ok. Put it in nutral on a flat ground where it woun't roll by itself. Then just get out and try and push it a little. It does not take a lot of force to make the car roll. Then see if it stops right away. You are looking to see if the brakes are dragging or anything like that.

[JGood]

That's not an accurate test for MPG. Next time, reset your trip meter, fill it up, and then see how much it takes the next time, and divide the mileage on the trip meter by the gallons of gas you were able to put in. You may get the same, but at least you will take human error out of the equation for fixing your problem.

[Joey Link]

Just curious, why isn't that an accurate MPG test?

E30 Wagen, we run regular (87 octane) in the ETA.

I just replaced the plugs and it seems to be running smoother but it could be the placebo effect. I'm fixing the stupid wiper arm issue now.

[smonkbmw]

joey, we run plus in whitneys car and she gets closer to 20mpg. i have a spare AFM if you want to try it.

[Mike325]

I run 93 in mine, but I also have the Turner chip. I still get way over 16 MPG. Try switching to the hiest grade fuel you have avalible to see if that helps.

[Funkmasta]

I got 15mpg in the M3, dont complain about your 16mpg. :p

Things to address/check
Plugs
Wires
Air filter
Cap/rotor
02 sensor
tire pressure

Those are the biggies. I know both you and Jenny are conservative drivers... so we can safely rule that out.

M30? ;)

[Joey Link]

Thanks for the tips. How much does it cost for a cap, rotor, and 02 sensor?

Anyone know off the top of their head the oil capacity of the engine, tranny, and rear diff of the '86 325e and '89 325i? How difficult is it to change?

[skuyler]

325i oil capacity is 4.5 qts if you change the filter (on my '90)
Tranny & rear diff are both about 1.5 qts (don't remember exact)

Cap & rotor, I don't remember exactly, but I think for both it was somewhere around $70.

02 sensors, "BMW" ones are like $50, whereas the ones for the 5.0 Mustang (same ones, just one extra wire I think) are ~$20.

[E30 Wagen]

I get at least 25mpg, combined, and i stress at least. I run either 89 or 93 octane. I'm usually around 27-29mpg.

Also, is it an automatic or 5 speed? I'm pretty sure you get lower mpg with automatic.

[euroshark]

M30?

I bet an E30 M30 could get 30mpg easy with the correct diff. If my 533i can get close, removing 700lbs can only help!

I wish I knew why your eta was getting 16mpg, thats horrible... Good luck!

[JGood]

Just curious, why isn't that an accurate MPG test?

It's just not. The fewer the variables, the more accurate your MPG reading will be. The only thing setting off that light is your fuel level sensor, and it's simply a float triggering a circuit for the light bulb in the dash. I've had that light come on, and I immediately fill up the car, and fit ~12 gallons in the car, other times I fill up as soon as it comes on and I fill up only ~10 gallons.

Your "problem" may not even be a problem. Maybe your getting 25 mpg.