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Old 01-02-2003, 12:06 AM   #1
imprezey
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Unhappy ridiculous gas mileage

Ive already posted about this before but things are going even worse then before. as of now, i am getting 15 mpg. this is city driving. on the highway i get a good 21 mpg. now im just getting mad. what could it be? i havent been doing any "spirited" driving at all.

I have a proECM and i run 91 octane on it. but even for doing this i still shouldnt be getting 15 mpg, thats just not right. so this is my plan, take out the chip and run 87-89 octane for a bit. if this doesnt work i dont know what i would do. bring it to the shop? im pretty sure i dont have a leak anywhere.. frustration.
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Old 01-02-2003, 03:45 AM   #2
Kostamojen
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Yes, try taking out the chip and see if it helps.
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Old 01-02-2003, 08:50 AM   #3
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21 mpg on the road isn't what i'd call good gas mileage...

before you yank the chip, check your plugs. i had a bout of bad mileage for a couple days, and everything else seemed normal...i checked my plugs, and one of them was fouled pretty badly from the car running rich.
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Old 01-02-2003, 01:07 PM   #4
Jademonkey
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You also might want to reconsider using a lower octane. I get about 23 city and 25 to 26 now with the winterized fuel. I get just about the same MPG with 87 and 89, but it takes a dive if I fill up with premium. I commute a lot in my RS, so I spent a lot of tiime running several tanks of each octane to figure out what it ran best at.
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Old 01-02-2003, 02:48 PM   #5
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Higher octane will drop your fuel economy... the higher the octane, the slower the burn (it's just less prone to detonation, which is why high performance vehicles require it).

With stock NA form I used to pull about 17mpg around the town, and around 22-23mpg on the highway running 93 octane (I ran it to prevent tip-in detonation that I was getting). In complete stock form on a road trip, I only once got up to 28mpg on 87 octane.
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Old 01-02-2003, 03:55 PM   #6
imprezey
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Quote:
Originally posted by RaceCarRiot
21 mpg on the road isn't what i'd call good gas mileage...

before you yank the chip, check your plugs. i had a bout of bad mileage for a couple days, and everything else seemed normal...i checked my plugs, and one of them was fouled pretty badly from the car running rich.
yeah i was being a little sarcastic . as for plugs, i just changed them for the first time a couple days ago. from the stock champions to ngk coppers. when i took the plugs out they look pretty burnt. im assuming its running rich. how would i fix this? i know that subies are known for running a bit rich. should i look into gettin a s-afc? im gonna pull the chip out first though and see if thats the cause. or should i just run 87 or 89 octane with the chip in?
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Old 01-02-2003, 04:31 PM   #7
DanzBorin
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the chip should not cause a drop in milage...

it actually should help, especially with premium gas...

the timing will be advanced more with premium do to the knock sensor not interfering...
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Old 01-02-2003, 04:36 PM   #8
imprezey
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Quote:
Originally posted by DanzBorin
the chip should not cause a drop in milage...

it actually should help, especially with premium gas...

the timing will be advanced more with premium do to the knock sensor not interfering...
thats exactly what i thought. maybe its something else, maybe i got a boob chip.. gonna test the chip with 89 octane today. when that runs out im going to take it out and run it with 89. ill see the results. i have a feeling that it might not be it.. that it has to do with the car running rich.
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Old 01-02-2003, 07:10 PM   #9
Keith99RS
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Do you always fill up at the same station or same brand gas?? Might want to try switching things up for a few weeks. Also, if CA screws around with the "winter gas" stuff, that could put the mileage in the trash too.
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Old 01-02-2003, 09:19 PM   #10
imprezey
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yeah i shop around. i found that chevron has good gas, something about that techron.. it runs a little better, maybe its just me though.
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Old 01-03-2003, 04:49 AM   #11
Kostamojen
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Note: You are not the first to have a massive decrease in gas mileage with a proecm
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Old 01-03-2003, 10:53 AM   #12
Jademonkey
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Despite what the pro ecm may or may not do, be sure to run several tanks of 89, and not just one.

Quote:
Originally posted by imprezey


thats exactly what i thought. maybe its something else, maybe i got a boob chip.. gonna test the chip with 89 octane today. when that runs out im going to take it out and run it with 89. ill see the results. i have a feeling that it might not be it.. that it has to do with the car running rich.
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Old 01-03-2003, 05:40 PM   #13
imprezey
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jademonkey: ill be sure to do that.

also, when im in going in first, i can hear the gas going through the fuel lines. its pretty loud... sounds like a lot of gas is going through. is this normal?
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Old 01-04-2003, 04:37 AM   #14
imprezey
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ok somethings wrong. when i turn on my car it sounds like it struggling a little bit. ok, thats not that big of a deal. well, after the car is turned on the rpm's fluctuate from 1.5k to 500. this is not normal. whats going on? the car drives fine however but this is definitely not normal.
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