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Max8
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Discussion Starter #1
So yeah, I live in California so I think winter is over (hopefully). Last week I put my summer wheels and tires back on and now I only get from 18-21.5 miles per galon. On the first thank I got around 21.5, on the second I could only squeeze 18.4 and this last one doesn't look to promising, and these are mostly freeway miles and I'm driving like a grany. I can't blame nothing else but my transmission. Engine is fine, MPGs with steelies remained constant (23-25mpg) So I don't know what the hell is going on[:(!]
 

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Dissconnect the battery and let the computer reset itself.
 

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Token Engin-nerd
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what is your summer tire size
 

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lol I think it's so funny when people like start worrying about their mpg when there is just a few miles difference. your mpg can't really be compared to the previous tank as it would be VERY inaccurate. there are just to many factors that contribute to your MPG...i would honeslty not worry about it...in a couple months take the average of of the individual fill ups MPG ratings and than hyou will have a much more accurate mpg reading.

my MPG fluctuates so much...i can go from 27 to 16 easily...and my driving habits don't change...another factor is the quality of fuel that you are putting in your vehicle. oil companies change their additives seasonally...even on a weekly basis depending on what quality of oil they are recieving...

my opinion..just don't worry abot it bro!
 

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Max8
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Discussion Starter #5
Dissconnect the battery and let the computer reset itself.
Done that already since I put the new wheels.

what is your summer tire size
215 45 R17

lol I think it's so funny when people like start worrying about their mpg when there is just a few miles difference. your mpg can't really be compared to the previous tank as it would be VERY inaccurate. there are just to many factors that contribute to your MPG...i would honeslty not worry about it...in a couple months take the average of of the individual fill ups MPG ratings and than hyou will have a much more accurate mpg reading.

my MPG fluctuates so much...i can go from 27 to 16 easily...and my driving habits don't change...another factor is the quality of fuel that you are putting in your vehicle. oil companies change their additives seasonally...even on a weekly basis depending on what quality of oil they are recieving...

my opinion..just don't worry abot it bro!
My mpgs are constant, I always get from 23-25. I always fill up at the same Chevron station, so quality of fuel remains the same. It is too much of a coincidence that as soon as I switch wheels, my mpgs had a big drop.
 

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It's your exhaust.........

Sorry I couldn't resist hahahaha

It might be a sign that an o2 sensor is on its way out, or maybe you just got a couple crappy tanks of gas. You really only get 23-25 mpgs? I'm sorry, I get 30 in my SVT [neener]
 

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Max8
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Discussion Starter #7
It's your exhaust.........

Sorry I couldn't resist hahahaha

It might be a sign that an o2 sensor is on its way out, or maybe you just got a couple crappy tanks of gas. You really only get 23-25 mpgs? I'm sorry, I get 30 in my SVT [neener]
Ha, how funny! I'm rolling on the floor [8] No, exhaust is constipated again, didn't you read my thread about the ticket I got because of the super loud exhaust? Anyways[offtopic] How can an 02 sensor going bad mess up with my mpgs? I have a header so, I don't think 02 sensors. It is true that I drive like an ass, that's why usually get 23-25 mpgs, plus my car is an auto. Now that I put summer rims on, I've been driving more decently and mpgs drop. I'm thinking that maybe the tires are the ones responsible, they are brand new.
 

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you dont think the udp effected anything? i mean technically i dont see how it would, but did you do any other mods since you last ran summer your summer wheels?
 

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Ha, how funny! I'm rolling on the floor [8] No, exhaust is constipated again, didn't you read my thread about the ticket I got because of the super loud exhaust? Anyways[offtopic] How can an 02 sensor going bad mess up with my mpgs? I have a header so, I don't think 02 sensors. It is true that I drive like an ass, that's why usually get 23-25 mpgs, plus my car is an auto. Now that I put summer rims on, I've been driving more decently and mpgs drop. I'm thinking that maybe the tires are the ones responsible, they are brand new.
Even with a header the first o2 is critical to the car running properly. The same applies for any FI car. Maybe the summer wheels weigh more? Combined with the timing being slightly advanced due to the udp install? Combine that with possible timing advance due to the udp install
 

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the quality of the fuel from the same station is NOT the same. there are meny factors to the fuel. it depends on when there delivery truck come mostly. if you fill up when or within a few hours of a fuel delivery, it sturrs up sediments on the bottm of the tank and it floats in the fuel and gets pumped in your tank...causing a decrease in fuel economy.
fuel temperature also makes a difference. best time to fill up in early in the morning between 4-7ish AM. the cooler it is...the more dence and you get more fuel instead of vapor. same with puming speed. pump as fast as the pump will pump the fuel...you get less fuel more vapor, less milage. pump slower=more fuel, less vapor.

so fuel economy isnt just in the car.
 

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Max8
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Discussion Starter #12
you dont think the udp effected anything? i mean technically i dont see how it would, but did you do any other mods since you last ran summer your summer wheels?
I'm not sure, but I drove about 2 tanks with the pulleys and the 15 steelies and no change in mpgs, it was after I reseted once again the ecu and put summer rims.


the quality of the fuel from the same station is NOT the same. there are meny factors to the fuel. it depends on when there delivery truck come mostly. if you fill up when or within a few hours of a fuel delivery, it sturrs up sediments on the bottm of the tank and it floats in the fuel and gets pumped in your tank...causing a decrease in fuel economy.
fuel temperature also makes a difference. best time to fill up in early in the morning between 4-7ish AM. the cooler it is...the more dence and you get more fuel instead of vapor. same with puming speed. pump as fast as the pump will pump the fuel...you get less fuel more vapor, less milage. pump slower=more fuel, less vapor. so fuel economy isnt just in the car.
I always fill up at night or very early in the morning (before I go to school), I'm not saying fuel is not a possibility, but it has not happened before. And weird thing is that it just happened as soon as I put bigger wheels.
 

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Max8
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Discussion Starter #13
ha, now that I think about it, I also changed the oil. Not only change it but switched it. I had 10-30 (my dad's fault) and now I switched back to 5-20 the same day I changed the wheels.... does that have an effect also? shouldn't it be the opposite?
 

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nah, assuming the stock wheels were 15, and the summer tires are 17, your odometer is being fooled. You are actually travelling farther than what your odometer is reading. So your mileage is pretty much the same or should be.
 

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Token Engin-nerd
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wheel diameter has nothing to do with odometer readings or MPGs or anything

it is all about the overall tire diameter.
 

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Token Engin-nerd
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OP said he is using 215/45-17


195/60-15: overall diameter 24.21 in revs/mile 859.1

215/45-17: overall diameter 24.61 in revs/mile 845.1
 
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