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Gas Milage


splitboarder
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How much did your MPG's drop when you lifted? I went up 6 inches, went from 190/85/14 to 215/75/15. I knew the milage would drop, but Im only getting about half of what I was getting.

 

But- my pvc hose is broken from the block to the air intake and my air intake box is just hanging at the fender, no longer connected to the tube coming up from the fender. Check engine light is on

 

I know I gotta fix those but man, this thing is eating gas

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Are you calibrating for tire size diference?

With bigger tires the speedo will read lower, you need to multiply your gas milage by the percentage in tire size change to get an accurate number.

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But- my pvc hose is broken from the block to the air intake and my air intake box is just hanging at the fender, no longer connected to the tube coming up from the fender. Check engine light is on

 

 

That hose at the back of the block needs fixed.

 

Right now you've got a huge unmetered air leak. Surprised it runs well at all.

 

Replace that hose. I put clamps on all my PCV hoses.

 

As noted, make sure your calculating the larger tires into your milage equations. For every mile your odometer reads, your going more like 1.1 or 1.2 miles.

 

my lifted rig with 235/75/15s is 24% off. so 5 miles on the odometer equals 6.25 miles

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Lol...is it broken or just unplugged? Mine came undone when I did the lift. What a pain to plug back into the speedo.

 

The speedo cable has been broken since I got it. I don't care to fix it anyway as it would read wrong with the tire size change.

 

I actually have a digital VSS in the tranny now. So someday I can wire up a digital one...

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I plan on having the speedo re-calibrated. But right now 60mph=70.

 

odometer ( trip) reads 51 so Im figuring I went about 60 miles

 

after compensation for the amount off, I used 1/4 of a tank in 60 miles.

 

aprox 3 gallons. Thats twenty mpg, but it seems to bo doing worse.

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My solution was to use one of those embossed tape things to print out sticky back labels for the new speed positions. I'd get it stabilized at a speed on the GPS and stick the label on where the speedo needle was pointing.

 

They weren't much use after dark, but they gave a good reference to get used to. Mine read about 20% low.

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I was told at the local dealer that the 97 is electronic, not cable. Cable is easy. just change the gear size at the tranny. Very easy for a speedometer shop to do a cable recal-change out.

 

looks like the yellow box will work, I just need to determine if I have a two wire or three wire system

 

Box cost 100 dollars

Speeding ticket going through small towns along the way to the mountains -350 dollars. (not to mention the insurance cost of a speeding ticket)

 

Kinda like the mastercard commercial- knowing the speed your going-priceless

 

I lifted my car to get further back on forrest service roads in the Eastern Sierra nevada Mountains. Lots of small towns ( Lone Pine, Independence,Big Pine, Bishop )

 

they like to drop the speed limit from 65 to 25 in town

you better be doing 25 or the man will come knocking

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I drove from Denver to Colorado Springs the other day in the Brat, going around 75mph to/from, and hit some traffic on the way home. I calculated 27mpg, after accounting for the larger tires(215/75/15). No lift though, SPFI EA81.

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I was told at the local dealer that the 97 is electronic, not cable. Cable is easy. just change the gear size at the tranny. Very easy for a speedometer shop to do a cable recal-change out.

Except for the fact that you have to remove and split a subaru transmission to change the speedo gear. 95 and newer are all electronic speedo's for the most part. The impreza may have stayed cable for another year or two after that.

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I was told at the local dealer that the 97 is electronic, not cable. Cable is easy. just change the gear size at the tranny. Very easy for a speedometer shop to do a cable recal-change out.

 

The driven gear cannot be changed without removing the trans.

 

And actually, I'm not sure you can interchange different size gears. The matching drive gear section is on the trans lower shaft. It is part of the spacer collar between the 1/2 and 3/4 gearsets.It matches the gear.

 

I think You'd have to change out the gear and the lower shaft collar.

 

 

Any recalibration for these cars would have to happen at the speedo.

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Except for the fact that you have to remove and split a subaru transmission to change the speedo gear. 95 and newer are all electronic speedo's for the most part. The impreza may have stayed cable for another year or two after that.

 

The last 97 impreza gauge cluster I had the displeasure of pulling out was a cable. They probably changed in 99 or whenever they went to the phase2 engine.

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  • 2 weeks later...

I did an EJ swap and lifted at the same time I've been driving it a lot now and I was trying to figure out my MPG. :banghead: its been a while since I've had to actually do math

 

I did a 4inch lift and went from 185/70/R13 tires to 225/70/R14 witch is 13.8% larger as according to http://www.miata.net/garage/tirecalc.html

 

so I filled up and drove 210 miles (as according to my factory speedo)

filled up again and it took 7.6 gallons.

 

correct me if I'm wrong but the math would be

 

210 x 1.138 / 7.6 = 31.4

miles x tires / gas = MPG

 

:banana:

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