[A4rings]

I installed an HVI Logic intake on my e92 335i and now the computer is reading an average of 10mpg. even when it is idling it shows between 8-10mpg. what could i have possibly installed incorrectly?

[lopealle]

maybe MAF is backwards (if these cars have them) i know oine time i put a intake in and i put the MAF backwards the car was running shitty and i couldnt figure it out. but hey i dont know hope i helped some how

[A4rings]

i didnt touch the MAF, i really hope i didnt get oil all over the MAF and ruin it. same shit happened in my a4

[cotmfk]

Take it out and see if you are back to normal?

[John 070]

Let us know if you find out what's going on--make sure you are giving yourself enough "distance" driven when you do your mpg calculation. I'd say at least cruise for 40 miles without interruption to get the mpg number.

I was concerned on whether my mpgs would change after the 35.4 software update (I think that's the version), but it didn't. I always avg. 21.7 to and from work, after a hundred+ miles. But if I fill up and go home, sure, my mpgs will only be about 12-16, depending on how many traffic lights I get stuck at. But also it's only 1.6 miles away, so not enough distance to make it a reliable figure...

[A4rings]

maybe its because i never reset the computer, how do i do that?

[I335]

Oy. Do you have an owner's manual?

[A4rings]

no actually my owners manual was missing, im waiting for the dealership to mail them to me.

[raceyBMW]

Installation of an intake really shouldn't change the MPG any....I also have the Logic HVI and it did not change the mpg for me. I don't know what you could have done wrong during with to get it to change like that. Try and calculate the mpg yourself next time you fill up, and see if its really that bad or not. Maybe try pulling the battery cable for a reset?

[galahad05]

No codes being thrown?

Is the idle rougher, and/or is the engine less smooth-sounding on acceleration? Is there any hesitation on heavy throttle tip-in?

Any heavy gasoline smell from the exhaust once the car's warmed up?

What does the instantaneous mpg display show upon steady-state level-road 70 mph down the freeway? What under deceleration?

[A4rings]

well the car honeslty doesnt act much differently than before but i do feel a loss of low end torque which i have been told is normal. when the car is idling the instantaneous MPG slowly goes down from 10 to 6. and whenever i am on the throttle the gas millage is super bad, but when i am cruizing or slowing down and not on throttle the MPG values seem correct. i guess im around 5 miles since the last reset and it says im getting 12mpg. also the idle is not rough at all and the car sounds normal. M

Maybe the intake is not fitting flush at the turbo inlets? i checekd all the lines and it seems to look fine.

To reset the computer in my audi i had to disconnect the battery and wait a few minutes and then reconnect it. then put the key in the ON possition (not turn the engine on) and wait for the throttle body to adjust itself, and then i could turn the engine over.

what is the process for the 335? thanks alot guys

[galahad05]

If you had an air leak, you'd know it--rough idle would be your most likely indication.

Also, over time the engine management computer will figure out the air/fuel ratios to get the best mileage and power sweet spot.


From your description of the steady-state, accelerating, and idle mpg readouts....everything seems normal.

Take your car out for a few more normal driving cruises. I'd expect that your average mpg would start to creep up to where you'd expect it to be. You just don't have enough time to get a true average yet.

[galahad05]

Originally Posted by A4rings

...
...

To reset the computer in my audi i had to disconnect the battery and wait a few minutes and then reconnect it. then put the key in the ON possition (not turn the engine on) and wait for the throttle body to adjust itself, and then i could turn the engine over.

what is the process for the 335? thanks alot guys

Basically, disconnect the battery for a few minutes. That's pretty much it.

[A4rings]

Originally Posted by galahad05

If you had an air leak, you'd know it--rough idle would be your most likely indication.

Also, over time the engine management computer will figure out the air/fuel ratios to get the best mileage and power sweet spot.


From your description of the steady-state, accelerating, and idle mpg readouts....everything seems normal.

Take your car out for a few more normal driving cruises. I'd expect that your average mpg would start to creep up to where you'd expect it to be. You just don't have enough time to get a true average yet.

yes but that in strictly stop and go traffic, i am only getting 12mpg? that would be horrible

[D335I]

Just posted bad mpg right after you. Im getting pretty poor mileage as well, 14-16 at best. I remember getting 18.5-19 sometimes in city only driving and I remember thinking this is awesome.

[A4rings]

drove around all day today, both stop and go as well as freeway and im still getting 12mpg. WTF is wrong with this thing, i think im just gonna take this POS intake off.

or should i try to disconnect and then reconnect the battery? anyone think that could fix the problem?

[CBR335]

Dude BTW the 335 doesn't have a MAF (TMAP), so that isn't the problem.

[A4rings]

hmmm i guess i have to try and change the intake out.. i'll let you guys know how it goes