On track mileage is fine (same 9-10mpg I was getting before) but highway mileage has dropped from 31-32 to 28-29. Doesnt sound like much, but it adds up to 30-40 miles per tank, and its noticeable.

Car runs fine, no CEL, no drop in power. I thought maybe the massive amount of **** I stuffed in my car for Expo was the cause, but was on the road sunday in an empty hatch and the mileage was the same.

All the ignition stuff was new beginning of the year, and I use BG44k or Motul fuel system cleaner in somewhat regular intervals. I hope it is not 02 sensor

Thoughts? I have not pulled the TB to see if its gummied up with carbon yet.

 

Wah? My window sticker says 26mpg, j00 are teh lucky!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Rguy &raquo;</TD></TR><TR><TD CLASS="quote">My window sticker says 26mpg</TD></TR></TABLE>

Highway?

I have been up to 34mpg driving easy, all highway with an empty car after a round of motul fuel and engine cleaner.

Maybe I could get more if i took the wing off and backed it down to 65-70?

 

I get around 32-33mpg constantly now. I got 35ish with a header and test pipe.

I get the best mileage at around 90mph.

But my window sticker does say 26mpg highway. hehe.

 

Too much beer lately?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by .RJ &raquo;</TD></TR><TR><TD CLASS="quote">On track mileage is fine (same 9-10mpg I was getting before) but highway mileage has dropped from 31-32 to 28-29. </TD></TR></TABLE>

RJ, you've been on the track every week for about a month, now.

This is subjective, but my own driving habits are a little more difficult to control when I've had a lot of track time in a row.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Wai &raquo;</TD></TR><TR><TD CLASS="quote">Too much beer lately? </TD></TR></TABLE>

I wish I dont even drink anymore.

Anyone got a used 02 sensor for me to try? Maybe I'll hook up the scanner and check the fuel trim.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by George Knighton &raquo;</TD></TR><TR><TD CLASS="quote">This is subjective, but my own driving habits are a little more difficult to control when I've had a lot of track time in a row.</TD></TR></TABLE>

I cruise 75-80 on the highway, which is about the only street miles the car sees. Any faster and the radio wont drown out the noise from the A032 super swampers.

 

a/f ratio during summer will yeld to lower mpg. on same ecu map car will run richer during summer.

 

Gas mileage can vary by 2-3 mpg, even on a long drive, due to a lot of different factors that have nothing to do with the car itself - prevailing winds (tailwind vs headwind), differences in elevation (uphill vs downhill), traffic (more speeding up and slowing down when there are more cars on the road), etc.

I got the same thing (31-32 mpg on the way to the Expo on Thursday, 28-29 on the way home on Sunday, same contents, same route, similar speeds). I chalk it up to differences in winds and/or traffic.

I wouldn't worry about it.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nsxtasy &raquo;</TD></TR><TR><TD CLASS="quote">Gas mileage can vary by 2-3 mpg, even on a long drive, due to a lot of different factors that have nothing to do with the car itself - prevailing winds (tailwind vs headwind), differences in elevation (uphill vs downhill), traffic (more speeding up and slowing down when there are more cars on the road), etc.</TD></TR></TABLE>

The mileage drop was consistent going to and coming home from beaverun last weekend, to/from expo as well as to/from richmond on sunday.

I am not going to spend any money on this problem yet because a 2-3mpg drop is cheaper than an o2 sensor, but I would like to know what the hell is going on.

I'll pull the plugs and TB tomorrow, I guess.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vtec.dc2 &raquo;</TD></TR><TR><TD CLASS="quote">a/f ratio during summer will yeld to lower mpg. on same ecu map car will run richer during summer.</TD></TR></TABLE>

no

 

That rainstorm Type aRrrr on the drive back north couldn't have helped mileage... least, I had to use more throttle to keep the car chugging through the lakes on I-95 and to get away from people who like to drive next to me before hydroplaning into my lane.

Might try an ECU wipe too... worked on the Type RS.

PS- release the e-brake

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by WRXRacer111 &raquo;</TD></TR><TR><TD CLASS="quote">I had to use more throttle to keep the car chugging through the lakes on I-95 and to get away from people who like to drive next to me before hydroplaning into my lane. </TD></TR></TABLE>

You mean people like me on bald A032's?

 

Must be nice. I swear I see like 24-25 highway miles. I dont even think of touching vtec unless I want to fill up the next day.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by .RJ &raquo;</TD></TR><TR><TD CLASS="quote">
I'll pull the plugs and TB tomorrow, I guess.</TD></TR></TABLE>

same tires and air pressures as when you were getting 32-33? that can cause that big of a difference..

but if the tires/pressures are consistent, I would reset the ECU to start.. it's free and easy.. when did you change the plugs and wires? that would be the next order of business.. it *could* be your primary o2, but I doubt it..

spraying some carb cleaner into the TB should clean it out, if there is any carbon in there.. do it with the car off and wipe it around VERY well.. hell, spray a little in there while the car is running if you want..

 

I typically get 30mpg to a tank, most of my commute is hwy though. when was the last time you cleaned the airfilter, or changed the fuel filter/ pcv valve?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by El Pollo Diablo &raquo;</TD></TR><TR><TD CLASS="quote">

no</TD></TR></TABLE>

???
.. explain if you will how 70 degree change in temps doesn't have an effect on air density.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vtec.dc2 &raquo;</TD></TR><TR><TD CLASS="quote">

???
.. explain if you will how 70 degree change in temps doesn't have an effect on air density.</TD></TR></TABLE>

I never said it didn't...what it won't affect, however, is the air/fuel ratio on Ryan's car.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mstewar &raquo;</TD></TR><TR><TD CLASS="quote">same tires and air pressures as when you were getting 32-33? that can cause that big of a difference..</TD></TR></TABLE>

Trip up was on my snow tires (34psi) and trip home was on my superswampers (34psi) as well as the trip to richmond (32psi) and home (38psi).

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vtec.dc2 &raquo;</TD></TR><TR><TD CLASS="quote">.. explain if you will how 70 degree change in temps doesn't have an effect on air density.</TD></TR></TABLE>

It has an effect on air density.

 

higher temps = air is less dense.

a/f ratio is air/fuel mixture.

air density doesn't change how much fuel goes in, but it changes how much air goes in, affecting A/F ratio.. why some people retune for summer/winter. why honda has 5 maps for rsx based on temps. what doesn't make sense here.

 

The weather has not had any significant change in the past month or two.

If anything, my trips over the weekend were in cooler temps than the past month.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by .RJ &raquo;</TD></TR><TR><TD CLASS="quote">

Trip up was on my snow tires (34psi) and trip home was on my superswampers (34psi) as well as the trip to richmond (32psi) and home (38psi).</TD></TR></TABLE>

so no correlation to tires then.. hmm.. yeah, I guess check plugs/wires and the TB/IM.. otherwise, just not worry about it.. it's not that bad..

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mstewar &raquo;</TD></TR><TR><TD CLASS="quote">it's not that bad.. </TD></TR></TABLE>

I know. Its not the gas mileage that bothers me, its that something isnt quite right.

RJ - pain in the *** about his car

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by .RJ &raquo;</TD></TR><TR><TD CLASS="quote">The weather has not had any significant change in the past month or two.

If anything, my trips over the weekend were in cooler temps than the past month.</TD></TR></TABLE>

yeah.. i realized this really won't apply in your case cause this is recent changes.. but what i'm saying is correct regarding a/f change..

i'd say give it few more fill ups, i'm not sure if you measure mpg same way as i do.. (the way i do it: fillup, drive some miles, then fill up again, divide total gallons filled by miles driven) if you did it same way, maybe it didn't fill all the way, leading to lower reading. maybe give it few more fill ups, see if it drops consistanly.

 

closed loop = 14.7 a/f ratio

ITR != RSX