Interesting MPG increase of ~11mpg

[mntn-biker]

I have a 2003 Base model with the original 1zzfe engine, 120k miles, and original plugs. A couple of years ago, I swapped in a 6 speed manual trans replacing my noisy bearing 5 speed and noticed my mpg's went down but my driving enjoyment went up along with being able to sustain and increase speed on uphills in hilly terrain. I did some mods/repairs recently and this is what my mpg findings were:

Oct/2012 - K&N SRI install - Seemed to give me more power, took a 3 hour trip north a few weeks ago and noticed my mpg was 25mpg traveling at 77mph avg (per gps)
Feb/2013 - Replaced IM gasket with Toyota red 1 (was doing the cold temp idle hunting during warmup - does not do that anymore), added Helix TB spacer, replaced TB with a bored out 1 courtesy of Maxbore.com (bored TB from 54.5 to 57.3) (nice work George!!!). I took a ~1:15 minute trip across the state today @ ~77mph avg and checked my mileage since I didn't see my needle move much like I normally would and voila, 36mpg!!! Could hardly believe it! FYI - I filled up both times the same by chucking the tank full of fuel (after the pump automatically kicked off).

Kinda thinking the IM gasket was the major contributing factor in this mpg increase (but I supposed it could be a combination of all of the above mods/repairs). Anyone else find this pleasant surprise after replacing their IM gasket?

Mike

[Chiadog]

Please replace the oem throttle body spacer and re-test your mileage! I'm guessing the spacer is improving mpg, seeing as how the gasket only caused idle speed hunting with a cold engine and mpg was tested with a hot engine. Thanks for this great information.
chiadog

[Rayven01]

Wow! You don't see 45% mpg increases every day. I want some of that!

[JohnO]

My guess is that the mileage in October was much better than 25 mpg or something was wrong with the car. 36 mpg seems closer to what a Vibe should do on the highway. A minor vacuum leak or a throttle body spacer shouldn't affect the mileage any.

[mntn-biker]

My guess is that the mileage in October was much better than 25 mpg or something was wrong with the car. 36 mpg seems closer to what a Vibe should do on the highway. A minor vacuum leak or a throttle body spacer shouldn't affect the mileage any.

My 25mpg was just a few weeks ago when I finally got around to checking it since I was thinking my mileage was kinda crappy and I was shocked when I only was getting 25 I'm happy now though

[cptnsolo77]

I hope I get a MPG increase when I change mine out. Im doing well now though but any ant increase would be appreciated

[tpollauf]

My 2.4L 5-speed manual achieved 36-37 mpg TWICE .... But at 15 mph slower than what was posted here. For going 75+mph those are excellent numbers

[ChuckstrPT]

Speaking of mpg... recently started getting about 25% less and am stumped. It's an '05 GT w/150k and a new clutch. I drive a lot for work. Normally was getting consistent 24-25mpg regardless of driving environment. I noticed recently, the gauge moving more quickly than normal. Normally well beyond 100 miles before I'm below 3/4 tank. Now, it's well past that at 100 miles. It's showing me 19-21mpg... My mechanic put it on the computer, found a ratio off 6% (something about the fuel ratio). He cleaned a sensor, got the ratio back to spec, and still no change in mpg. Put in new plugs, no change. Fresh filter, no change. It seems to run fine, sounds fine, and pulls as usually.... I'm stumped. Any ideas??

[Chiadog]

4 new tires? Brake job, brakes dragging? Any changes at all? E-85? Seems pretty weird!
chiadog

[ChuckstrPT]

4 new tires? Brake job, brakes dragging? Any changes at all? E-85? Seems pretty weird!
chiadog

I am in need of tires (new clutch ) and I'm thinking that may be contributing. I didn't think the E85 would do that. And I've been driving it the same for 3 years (driving for work) largely stopping at the same gas station, filling the same way, and never noticed this before...

[Chiadog]

4 new tires? Brake job, brakes dragging? Any changes at all? E-85? Seems pretty weird!
chiadog

I didn't think the E85 would do that. ...

E-85 is 85% alcohol and has about 33% less energy per volume than pure gasoline. Did you just start using E-85?
Old tires won't cause an abrupt mpg change - new ones will if they are less effecient than the old ones.
chiadog

[mntn-biker]

I didn't think our 1st gen Vibes were engineered to run E-85.... I've heard that it costs less but you get worse mileage so maybe it all works out the same in the end except that I thought E-85 was not good for a "non E-85" engine???

[ChuckstrPT]

4 new tires? Brake job, brakes dragging? Any changes at all? E-85? Seems pretty weird!
chiadog

I didn't think the E85 would do that. ...

E-85 is 85% alcohol and has about 33% less energy per volume than pure gasoline. Did you just start using E-85?
Old tires won't cause an abrupt mpg change - new ones will if they are less effecient than the old ones.
chiadog

I've been fueling up at the same station for years. Unless they started using something different, I dunno. I think I looked, and didn't even notice a "contains less than 10% E85" sticker that I have seen at other stations. It did seem to come on rather quickly, but after I found a consistent 24-25mpg, I really stopped checking regularly. Dunno the last time I calculated, prior to me noticing dropping way below 3/4 tank with way less than 100 miles on the clock.

[CharlesinGA]

My mileage is all over the spectrum no matter how careful I am to fill it. Something about the filler neck and tank design. I set up a spreadsheet to track mileage, only way to know for sure. Checking one or two tank fulls is not a good indication of the mileage of the vehicle.

You can find a copy of my Excel (Office 2010) spreadsheet in this post. viewtopic.php?f=11&t=36538&start=200#p429588 The post has some basic instructions for clearing out the spreadsheet and entering data.

Charles

[mntn-biker]

My mileage is all over the spectrum no matter how careful I am to fill it. Something about the filler neck and tank design. I set up a spreadsheet to track mileage, only way to know for sure. Checking one or two tank fulls is not a good indication of the mileage of the vehicle.

You can find a copy of my Excel (Office 2010) spreadsheet in this post. viewtopic.php?f=11&t=36538&start=200#p429588 The post has some basic instructions for clearing out the spreadsheet and entering data.

Charles

Every time I check it, I chuck it full of fuel prior to the trip and right before I check the mileage. So far it is 35-36mpg. Depends if I drive 75 or 80...