Poor gas mileage
Feb 18, 2008, 06:27 PM
#61
which clamps did you windup tightening? I think I still may be leaking boost a little bit somewhere. as I can not seem to hold a steady 20psi in the system. It builds pressure in the system pretty quickly which leads me to beleive that it is a somewhat tight system. I am still not sure if I am doing the boost test correctly.I disconnected the MBC and plugged those lines to avoid the natural bleeder whole the MBC has. I then removed the intake pipe from the turbo and fitted my plumbing fitting with air hose valve securely. plugged the PCV line up as it was connected to the intake which left it open and proceeded to fill. after I while air seemed to be working its way out of the oil cap. not sure it that was normal or if I was doing something wrong. After I realized it was leaking from there I stopped all testing till I could figure out why it would do this. any help would be great. thanks guys
Feb 18, 2008, 07:06 PM
#62
For me it happened to be a combination of the throttle body seals which I replaced with the WORKS high pressure seals, and the turbo outlet and turbo inlet hose clamps. While I was trying to swap my dpwnpipe I messed with the hose clamps while under the car and the were snug, but not tight like the rest of the clamps. I still want to get T-Bolt clamps, the worm clamps look real tired.
Feb 18, 2008, 07:45 PM
#65
So I filled up last night, calculated my MPG......14, last tank was 15.1MPG. This is a 50/50 mix of city and highway driving. Normal 3k-3.5k shifting, with the occasional 15sec spirited run.
Mods are:
-Green filter
-HKS turboback
-Tune
I am running a test pipe but the O2 sensor is plugged in and no check engine light is on. Even when I beat the mess out of my 350z, the worst I got was 17, usually I averaged 20-21. One thing that I did notice is that my idle is right around 1k RPM. Every once in a while, it will blip down to 800ish, for a 1/2 second, then back to 1k. It will do it 4-5 times then stop. I have no clue what it could be. I bought the car used, it had DEVO Tuning stickers on it and by looking around I know it had a BOV at one point, at least a cat-back, and it appears to have suspension mods done at one point. Suggestions as to why my MPG is in the toilet and why it seems my idle is on the high side?
***Update 1/28/2008***
Figured I would give an update to help narrow down problems or come up with other options.
-I have Works throttle body seals coming tomorrow.
-I was tuned by inco9nito99 for my mods
-Car just turned 27k miles
-I know for a fact now the clutch was done recently
-I just went through a tank of Shell 93, 75% highway 25% city staying under 5 psi of boost.............18mpg. An improvement, but still not where it should be.
-Checked to make sure hose clamps (worm style) are tight.
I have yet to:
-Change fuel filter (If needed)
-Check/change plugs. I have BPR7s. Should be ok for my mods right? Boost is around 22-23psi, I have seen it spike to 25psi once.
Short of fuel physically leaking somewhere(none that I can see), I'm starting to draw a blank here.
Mods are:
-Green filter
-HKS turboback
-Tune
I am running a test pipe but the O2 sensor is plugged in and no check engine light is on. Even when I beat the mess out of my 350z, the worst I got was 17, usually I averaged 20-21. One thing that I did notice is that my idle is right around 1k RPM. Every once in a while, it will blip down to 800ish, for a 1/2 second, then back to 1k. It will do it 4-5 times then stop. I have no clue what it could be. I bought the car used, it had DEVO Tuning stickers on it and by looking around I know it had a BOV at one point, at least a cat-back, and it appears to have suspension mods done at one point. Suggestions as to why my MPG is in the toilet and why it seems my idle is on the high side?
***Update 1/28/2008***
Figured I would give an update to help narrow down problems or come up with other options.
-I have Works throttle body seals coming tomorrow.
-I was tuned by inco9nito99 for my mods
-Car just turned 27k miles
-I know for a fact now the clutch was done recently
-I just went through a tank of Shell 93, 75% highway 25% city staying under 5 psi of boost.............18mpg. An improvement, but still not where it should be.
-Checked to make sure hose clamps (worm style) are tight.
I have yet to:
-Change fuel filter (If needed)
-Check/change plugs. I have BPR7s. Should be ok for my mods right? Boost is around 22-23psi, I have seen it spike to 25psi once.
Short of fuel physically leaking somewhere(none that I can see), I'm starting to draw a blank here.
-Accelerating while your in as much vacuum as possible. The needle at 0 is not the best either, you should be under that as well while accelerating.
-keep cruising rpms below 2,000 . This is probably the most important because you hold the rpms instead of just use them for a few seconds as you accelerate and shift.
-avoid accelerating into high rpms, shift around 2.5k rpms
-always engine brake. You dont necessarily have to down shift and rev match, just keep it in gear as you brake. Engine braking shuts off the injectors so your saving fuel.(dont forget to pop into neutral as you approach closer to 1k rpms)
-Make sure you have good tire pressure. (32-35 psi)
Try that and report back to us on your MPG's.
Also I'd check and clean the Maf sensor. The previous person probably used over oiled air filters or it some how got really dirty.
Mar 1, 2008, 06:58 PM
#66
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jeez! i thought i had it bad. all the mods on my car and i never got tuned yet. just hit 41k miles and finally changed my spark plugs. topped it off with 93octane and reset the clock. so far ive covered 107 miles and i am just barely under 3/4 full. but that makes no sense because i never got tuned. i never heard of an evo gettin 380 miles per tank. my civic did that easy. i think imma go fill it up again and start from scratch to make sure.
Mods are:
helix intake
megan exhaust manifold
2.5" full upper & lower intercooler piping
hks fmic
3" turbo back
walbro 255
No tune (still stock ecu)
(alot of other mods but they are more cosmetic)
Mods are:
helix intake
megan exhaust manifold
2.5" full upper & lower intercooler piping
hks fmic
3" turbo back
walbro 255
No tune (still stock ecu)
(alot of other mods but they are more cosmetic)
Last edited by EVOJR$; Mar 1, 2008 at 07:07 PM.
Mar 1, 2008, 10:12 PM
#67
jeez! i thought i had it bad. all the mods on my car and i never got tuned yet. just hit 41k miles and finally changed my spark plugs. topped it off with 93octane and reset the clock. so far ive covered 107 miles and i am just barely under 3/4 full. but that makes no sense because i never got tuned. i never heard of an evo gettin 380 miles per tank. my civic did that easy. i think imma go fill it up again and start from scratch to make sure.
Mods are:
helix intake
megan exhaust manifold
2.5" full upper & lower intercooler piping
hks fmic
3" turbo back
walbro 255
No tune (still stock ecu)
(alot of other mods but they are more cosmetic)
Mods are:
helix intake
megan exhaust manifold
2.5" full upper & lower intercooler piping
hks fmic
3" turbo back
walbro 255
No tune (still stock ecu)
(alot of other mods but they are more cosmetic)
Also what driving technique are you following. How do you accelerate (on boost/ off boost or granny slow), rpms shift at, stop (in gear or neutral), cruise rpms etc...
These things helps us know how the mpg's a person gets has been achieved.
Mar 2, 2008, 05:58 AM
#68
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The needle always goes down slow during the first 3/4 or 1/2 tank. Then it drops quick. How many gallons did you fill to make a full tank from that 107 miles ( miles travelled / gal filled.)
Also what driving technique are you following. How do you accelerate (on boost/ off boost or granny slow), rpms shift at, stop (in gear or neutral), cruise rpms etc...
These things helps us know how the mpg's a person gets has been achieved.
Also what driving technique are you following. How do you accelerate (on boost/ off boost or granny slow), rpms shift at, stop (in gear or neutral), cruise rpms etc...
These things helps us know how the mpg's a person gets has been achieved.
Mar 2, 2008, 07:32 AM
#69
here is my update. I have been seeing 230-260. On one tank that was mostly high way, mostly cruising and not too much boosting I saw 280 miles. cruising between 75-90 depending. so I know right off the bat, that is not going to yield to great in an MPG. When I filled up I put in 13.1 gallons of fuel (93 octane) now that is stll one 21 mpg which is not great. But I guess its livable with an EVO. Some people are seeing really high numbers which is awesome. but they way they are driving them, who cares if your in an evo any way. No offense guys. I am just saying that if I wanted to shift at 2500-3000 and coast to a stop I might be driving the wrong kind of car. I would like to maybe see a little better fuel efficiency out of the car, but for they way it drives 21mpg is not terrible.
Mar 2, 2008, 07:33 PM
#70
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My car has 13,000 miles. Around December I started to get poor gas mileage too. On a daily basis I used to get around 220-230 miles and that had dropped to around 190-195, which is quite a big difference.
Recently I decided to use one of the fuel system cleaners. I used the techron fuel system cleaner. After half a tank I refilled again because of a trip and on mostly highway driving I saw 307.4 miles with the gas light on for the last 7. I filled up the car with 12.99 gallons so now with city driving I want to see if I will go again to the usual ~220 miles city.
I think this stuff works and probably I will start using it every around 5,000 miles...
Recently I decided to use one of the fuel system cleaners. I used the techron fuel system cleaner. After half a tank I refilled again because of a trip and on mostly highway driving I saw 307.4 miles with the gas light on for the last 7. I filled up the car with 12.99 gallons so now with city driving I want to see if I will go again to the usual ~220 miles city.
I think this stuff works and probably I will start using it every around 5,000 miles...
Mar 3, 2008, 03:17 PM
#73
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ok heres an update to my previous post. i just got to half a tank and the clock said i covered 159.4miles. thts normal driving (see previous post) with an occasional leaded foot. i usually fill up as soon as the light comes on and that is between 11.9 and 12.1 gallons. according to the calculator, im basically getting 26 mpg. so i guess its not as bad as i thought. but what does that say for my mpg if im about to get cams and a dyno tune? will it be better or worse? i have a bunch of bolt on mods and never tuned the car yet.
Mar 3, 2008, 03:49 PM
#74
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ok heres an update to my previous post. i just got to half a tank and the clock said i covered 159.4miles. thts normal driving (see previous post) with an occasional leaded foot. i usually fill up as soon as the light comes on and that is between 11.9 and 12.1 gallons. according to the calculator, im basically getting 26 mpg. so i guess its not as bad as i thought. but what does that say for my mpg if im about to get cams and a dyno tune? will it be better or worse? i have a bunch of bolt on mods and never tuned the car yet.
As far as adding cams and getting tuned, you probably won't see much of a difference. In 2004 when I first got my car I averaged 20.84 mpg. I was stock for most of that year. With all the mods in my sig I've averaged 20.82 mpg with similar driving. Also, during long road trips my car averaged 24-25 mpg stock and averages the same now.
-Paul
Mar 3, 2008, 03:52 PM
#75
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Without filling up and finding out how much gas you've actually burned up, you have no idea what kind of gas mileage you've been getting with this tank of gas. The 1/2 tank mark means you've used somewhere between 6 and 9 gallons, so you've gotten somewhere between ~18 and ~26 mpg.
As far as adding cams and getting tuned, you probably won't see much of a difference. In 2004 when I first got my car I averaged 20.84 mpg. I was stock for most of that year. With all the mods in my sig I've averaged 20.82 mpg with similar driving. Also, during long road trips my car averaged 24-25 mpg stock and averages the same now.
-Paul
As far as adding cams and getting tuned, you probably won't see much of a difference. In 2004 when I first got my car I averaged 20.84 mpg. I was stock for most of that year. With all the mods in my sig I've averaged 20.82 mpg with similar driving. Also, during long road trips my car averaged 24-25 mpg stock and averages the same now.
-Paul
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