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View Full Version : Recent dip in fuel economy...very puzzled



UCB
07-21-2007, 09:05 AM
I know its an evo, I know its high performance, so I dont expect too much in terms of fuel economy, but lately it has taken a dive. Normally with mixed driving, I get about 240 miles a tank

Past 2 tanks, which have been 50/50 or if anything more highway, I've been getting ~200 a tank, or roughly 16-17mpg MIXED. If it was all city I would be ok with it, but I cruise at like 70mph, so it shouldnt be that bad. 3 weekends ago on my trip to LA I got 23mpg or so all highway

Things ive noticed

-I hear the walboro whining, a lot now. I know its typical, but I've really only noticed the sound as of late, not sure if its actually different, or I just finally started to notice it
-car seems to be running hot, when I drove up to oakland last weekend for the auto-x, as soon as I stepped out of the car I got hit with a wave of heat from the engine bay
-noticed on 2 ocassions, fresh coolant coming out of the over-flow can, and the line to the can is def full of hot coolant after driving


I just change the oil before the auto-x, changed the tranny fluid 2 days ago. Oil level is 2-3mm above the full notch, not sure if thats enough to have the crank wading in oil

What else could it be? Air filter is fresh (<2k miles), car only has 15k miles on it so I dont think the front 02 can be fouled as I only run 91. The car did see some abuse 2 weekends ago in the form of 8 or 9 passes at sac, and I auto-xed it last weekend, but I think the problem started before the auto-x

Perhaps the brakes are grabbing slightly? I need to log some cruising to see what the load and IDCs are at

oneillevo
07-21-2007, 09:26 AM
I just blame it on the heat of summer LOL

Positron
07-21-2007, 09:33 AM
Could be a bad batch of gas this past week or two? I noticed my mileage slightly dipped 10-20 miles this past tank.

UCB
07-21-2007, 09:35 AM
hmm not sure, both were 76, 2 diff stations

Positron
07-21-2007, 09:36 AM
I fill up at 76 also. One on McKee and 101. Other one at McKee & Capitol Ave.

UCB
07-21-2007, 10:25 AM
mine was at lawrence/arques and on trimble/101

Dunno whats going on...sub 200miles per tank FTL

JDMevoBOOST
07-21-2007, 10:29 AM
dude hahah....city/hwy mixed I have NEVER gotten more than 18 mpg....and that was even when it was stock. Maybe I have a heavy foot or something. My walbro has been loud lately too.

But yah the only time I got more than 20mpg was straight freeway driving and I was purposely trying to drive smoothe, no throttle feathering at 70-80.

I usually get 170-200 and usually fill up 11-12 gallons

Positron
07-21-2007, 10:35 AM
damn Ken lol

My avg is 250-300. I have a soft foot ^_^

mtsevovii
07-21-2007, 10:41 AM
ive had my share of bad mpg... used to get around or less than 200/tank. but that was mainly due to not tuning the car.


now i ave 240-270/tank

or if its all freeway i ave around 280-320/tank

drive down to SoCal last week i hit 340/tank... wish i had that milage all the time.. :(

earlyapex aka jack ass
07-21-2007, 12:52 PM
The FP will get a little louder in warmer weather. On a hot track day, after a session, mine screams.

UCB, did you get your fuel trims in check from last time? What are they now?

Travisivart190
07-21-2007, 12:53 PM
I bet it's just bad gas, but honestly that's about what I was getting. I was getting 150-180 at the 1/4 mark of the tank ( I just try to keep gas in the car at all times, I don't wanna get stuck somewhere :P ). After the intake and exhaust, with a tune, I have been getting over 200 to the 1/4. Just driving down here to San Luis Obispo, I got about 260 miles for 11.555 gallons of gas. 22 mpg isn't too shabby considering I wasn't even expecting to save any gas :D

warpspeed
07-21-2007, 01:11 PM
I average 280 but it's all freeway ever since I got the car.

dl_EVO
07-21-2007, 04:36 PM
I get 200-220 mixed.

XVeloX
07-21-2007, 04:52 PM
Sounds like a case of lead foot :P

What are your mods? Your tune?

Have you checked the tune in the warmer weather? If its knocking during pulls (not just WOT, but even like half as well) it could add in a bit of fuel...

dohcvtec
07-21-2007, 07:24 PM
Jesus, I have never gotten any better than 230 miles to a tank in my car, ever!

Limeyboy
07-21-2007, 08:10 PM
well if its using more fuel consistently over several different tanks of known good gas, then its running rich. bad sensor feedback? loss of metered air? logs should help when you do em :) try a couple other gas stations. your local fill up may have just bought gas without the additive package.

UCB
07-22-2007, 10:14 AM
k will try that since my tank is currently empty. Will try to get some logs today as well

MarkSAE
07-22-2007, 04:39 PM
Could it be the stations you're filling up at? I seem to usually get 10-20 miles more per tank if I fill my car up on an uphill slope. I know mpg #s can get skewed by the "slope effect".

You should try to minimize the variables and fill up at the same station, same pump, same car orientation at the pump, etc...

Limeyboy
07-22-2007, 05:16 PM
Also, I recently cleaned my MAF. It was covered in oil from the recirc system. Used proper MAF cleaner, and have gained what seems to be about 4 MPG city.

UCB
07-22-2007, 10:11 PM
Could it be the stations you're filling up at? I seem to usually get 10-20 miles more per tank if I fill my car up on an uphill slope. I know mpg #s can get skewed by the "slope effect".

You should try to minimize the variables and fill up at the same station, same pump, same car orientation at the pump, etc...


dont think thats it

Changed my radiotor fluid today, will consider the maf cleaning, I did see some oil blow by in the maf

TogueMonster
07-22-2007, 10:19 PM
WTF?!Â* Â*I only get about 200 mpt.Â* Then again, I like to hear my turbo spool. :wink:

JDMevoBOOST
07-22-2007, 10:27 PM
Yah some of these guys are getting crazy mileage...makes me think....I have ALWAYS filled up at 76 except for the first tank of gas bought for me by Veracom at some hole in the wall gas station.

I have either filled up on Judah and 19th or the one by Westlake Plaza....it's kinda harde to believe that I'd get bad gas every time from there. But then again those two stations are cheaper than the others.

On another note I have never been able to not boost the car while driving hahaha....it's just too fun....so I guess if you guys are shifting at like 3200 every shift for the whole tank then I guess I can see it. But I also live on a steep ass hill and when i go to my mom's house it's on a hill too.

On my way to Sac I drove 70-80mph the whole way in 6th and got like 22mpg hahaha and you guys have seen my AFR's it's not like I'm running rich or anything. I dunno what the hell is wrong with me.

JDMevoBOOST
07-22-2007, 10:28 PM
wow 4mpg from MAF cleaning? maybe I should give that a try...maybe it was dirty from the dealer?

Limeyboy
07-23-2007, 07:52 AM
thats a guesstimate. ill try to work it out properly at some point. But improvement? yes definately.

UCB
07-23-2007, 09:57 AM
WTF?! I only get about 200 mpt. Then again, I like to hear my turbo spool. :wink:


yah..I've gotten 300+ a tank on highway trips in the past (26-27mpg)

So to see it dwindle to 200 was bothersome. Gotta fresh tank of gas, nearly full fluid swap, so lets so how this tank goes. So far 40miles and just a hair past the full line

MarkSAE
07-23-2007, 10:09 AM
Have you checked your tire pressures lately?

I've always noticed that I get better mileage on the first tank of gas after I come back from the track (where some 100 octane was used). So it seems like my car gets slightly better mileage w/ better octane. Perhaps you've just been getting some bad gas.

JDMevoBOOST
07-23-2007, 10:12 AM
what are u guys setting the stock tires at on the street? cold pressure?

UCB
07-23-2007, 10:13 AM
Yeah I've been meaning to check tire pressue. I was at 36 all around 3 weeks ago

MarkSAE
07-23-2007, 11:02 AM
I run around 40 cold when I drive on the street.. lol.. gotta maximize fuel economy.

UCB, did you change tires recently?

UCB
07-23-2007, 11:04 AM
Switched to my advans a litte more than 3 weeks ago

PANGES
07-23-2007, 11:20 AM
Funny thing... I noticed I only got 180 miles of mixed driving out of my last 11.5 gal fill up. I usually fill up around 11.3-11.5 gallons each time and get around 220 miles on the tank. Shrugs.

MarkSAE
07-23-2007, 01:29 PM
Switched to my advans a litte more than 3 weeks ago


What tires did you switch from? I bet you this was the major contributor to your decrease in fuel economy. A lotta people on evom.net reported gains in fuel economy after switching to less aggressive tires.

UCB
07-23-2007, 01:48 PM
all seasons to advans. But I rolled on the advans back up from LA and the car seemed fine. *shrugs*

MarkSAE
07-23-2007, 01:54 PM
Advans are almost like R-comps. They're really sticky compared to all-seaons. Try switching back to your all-seasons for a few weeks to see if your mpg goes back up.

UCB
07-23-2007, 02:38 PM
lol, not worth it :P

whtrice
07-23-2007, 04:54 PM
Wonder if it's the summer gas reformulation? ...No more MTB's ...Maybe using more ethanol as an oxygenate? Fuel definately has a different smell to it now. E85 will really kill our mileage but we all could run 100+ octane tunes.

overdrive
07-23-2007, 05:25 PM
UCB,
You should check your tire pressure. Being off by a little can affect your fuel economy. Besides that, its getting warmer and having a lead foot can also lead to bad fuel economy.

Last tip: I also read a brochure about getting more mileage when you fill up. They say to fill up at night when its cooler (less evaportation from the tank, compared to filling up on a very hot day).

Hope that helped.

UCB
07-23-2007, 05:50 PM
I live in san jose, its really not THAT hot down here. So yeah, ill check my tire pressure. Still need to log the car as well. Ill be driving down to monterey this weekend so that will be a good test as well

JDMevoBOOST
07-23-2007, 06:19 PM
On another note, have you checked your alignment?? I know that messed up toe can screw your mileage as well.

warpspeed
07-23-2007, 06:35 PM
Besides all the advices giving, fuel mileage also depends on the speed you are driving. I know it's hard but I did a non scientific test by driving my Evo @ 65-70 mph and my gas mileage went up. :)

UCB
07-23-2007, 06:36 PM
i usually cruise at 70, anything higher rpms are too much and it eats gas

Positron
07-27-2007, 03:21 PM
For the second tank in a row, my gas mileage has also dipped slightly. Same style of driving like I normally do. Nothing crazy, no lead foot or engine braking.

Might be the hot weather in San Jose or bad batch of gas at the 76 station on McKee/101 freeway. I will fill up at another 76 next time.

I am going to put a bottle of Cheveron fuel cleaner and see if that works and also raise my tire pressure to 36/38psi. Its set at 32psi right now. My car has close to 28k miles on it now. 06 Evo IX.

UCB
07-27-2007, 03:58 PM
3rd 76 station, still sucks. Looks like 220miles for this tank, only 80 of those were on the street

mtsevovii
07-27-2007, 04:03 PM
damn.. this heat is getting to my car too... car feels like crap. and i just filled up. only ran ~220/tank too this time.. :(


edit, then again.. ive been running AC now too...

PANGES
07-27-2007, 04:20 PM
My car has been feeling good. However, I live in the fog. :lol:

Positron
07-27-2007, 04:41 PM
Doesnt gremlins or hobbit creature live in the fog?

=P