what does your m20b25 get mileage wise?

[Kozworth]

Ive run into an issue. I was getting terrible mileage then i had thought i fixed it by reconnecting the vacuum line to the purge valve, assuming the engine would be burning the hydrocarbons now..

Anyways, even so i am getting about 17 mpg. Being easy on my car. I have to run 91 because of the bav chip and have a 3.73 lsd rear. I am going to check my o2sensor monday, but i do not have a richcondition (plugs are white and exhaust isnt black) well i guess its safe to say if it was rich it wouldnt be overly rich.

I drive an easy 40 miles to school and back 4 days a week plus all the places i drive are all about 15 minutes away from where i am. Obc says i am getting 21 but from what ive read obc is a little generous. I do mostly highway driving.

Anyways, i am wondering what you guys with different rears or just m20b25s get in general. Ive read low 20s is average and have also read that they arent hard to get mid high 20s on highway driving. I am trying to see whats the norm in order to decide my fate if i can offord this car (goes easily thru 10 bucks a day and i only get 220 a week so it takes nearly a 3rd of my check on a good week)

[nando]

The obc is accurate if you haven't messed with stuff.

Are you using fuel with ethanol in it?

I get 17-25 with 4.10s in my 2.8 stroker.

[Kozworth]

If i am not mistaken all fuel in nj has 10% ethanol.

Maybe my obc is quirckey.. if i start my car it doesnt restart the average mpg counting.. it also has an avg mpg and avg m/g which i didnt understand. But when id hold the set/reset the obc sometimes ddisplays 40mpg and shoots around back down ( id be crusing but no way crusing would i get 40 mpg becuse i do mostly highway driving as i had stated)

[mikeb23ft]

My OBC is pretty accurate. I got 28 mpg doing three hours of 65 mph two lane driving. I think that's pretty good.

[Kozworth]

See i am getting all ranges. Any other opinions

[NeedaBimmer]

My OBC reads 18.3-18.9, city only. I also have a 3.73lsd.

[strad]

I see about 18-19 city and 24-25 hwy with my 92 cabrio 5 speed. 3.73 open rear end.

[paperplane94]

Check using the good old fashioned way...

Fill-up to full.
REcord the mileage.
Run low on fuel.
Fill-up to full and record the gallons purchased.
Record mileage.
Find the difference in mileage.
then do this:
GALLONS PURCHASED / DIFFERENCE IN MILEAGE(traveled mileage since last fill-up) = MPG

[stamar]

I believe the orignal epa was 22 29

my record is 28 for a 1000 mile freeway trip. That was very disapointing. also considering in a perfect world you should beat the epa mpg.

I have since replaced the o2 sensor but havent gotten a repeat experiment. I have extremely good tune as far as plugs and wires. I have a feeling i have a leaky injector or a vacuum leak though.

It just feels like it should get better gas mileage. the reason is... well my 98 infiniti i30, with a 3.0 liter and an auto could get 30 mpg. And it weighs more too.

When i switch to a chip and a 4 pintle injectors im just feelin 30 mpg

[stamar]

The obc is accurate if you haven't messed with stuff.

Are you using fuel with ethanol in it?

I get 17-25 with 4.10s in my 2.8 stroker.

I have read the obc is almost exactly 1 mpg over.

[Kozworth]

II forget where i read it but i read somewhere obc was/like 30% over generous.


I put in 5 gal and got half talk its safe to assume the tank is about 10gal correct?

In the process of logging mpg and then testing the o2sensor tomorrow

[stamar]

no thats not correct.

in order to test fill it up

hit the trip meter. then when its halfway down go to the same gas station and fill it up ( because you need it to shut off at the same time)

write down the gallons you filled it up say 6.8 then the miles say 136

thats exactly how many mpg you got.

do it all week on a post it on your dash.

[Kozworth]

So it seems my mileage is getting city mileage on the highway.. usually going 60-65 at about 2.5k to 3k.

[evandael]

OP,

a number of other factors can contribute to poor mileage.. brake caliper dragging, under inflated or very sticky summer tires, bad wheel bearings, driving style.. if you truly feel that the motor is in to condition I would start an evaluation of the rest of the car.

for the record i didnt have a b25 but i imagine you should ne seeing mid 20s highway at 65 mph average.


good luck!

[nando]

I have read the obc is almost exactly 1 mpg over.

Well, you read wrong.

Ethanol will make a difference in mileage. What about your thermostat and coolant sensor? How hot does your car run?