Gas Mileage Problems...TOOO LOW!
07-12-08, 04:42 PM
#61
Just make sure your air filter doesn't look like mine. I had been taking the car to an oil change place that listed "Checked air filter....OK" on the invoice each time. I didn't drive/maintain the car exclusively for the past few years, so I assumed someone had been checking and replacing the air filter. I thought it was being replaced on the occasions when I didn't take it for the oil change. That's the last time I will trust an oil change place to do what they are supposed to.
Although I have to say I had recently been getting about 20mpg on 50/50 driving which is good.
Although I have to say I had recently been getting about 20mpg on 50/50 driving which is good.
10-22-08, 07:17 AM
#65
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My thesis is that there is no advantage to using high test gas to regular. I changed to 97 octane about 20 months ago and have had absolutely no problems of any sort. My mileage is from 19-21 in the city and from 23 to 27 on highway driving, depending on conditions. There is no hesitation, pinging, or missing. I would say the results are worth it.
10-22-08, 03:47 PM
#66
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97 octane? do you mean 87 octane?
there's a reason (probably previously stated) that youre only supposed to use premium. our engines are higher compression engines which means that each cylinder creates hotter combustion. the grade on fuel (octane) is its resistance to detonation, the higher the grade, the more resistant it is to detonation (knock). when you use lower octane your engine will start to knock(b/c it burns at a lower temp), the piezoelectic sensor will sense this and send voltage to your ecu which in turn will retard timing until it doesnt get any more voltage from the knock sensor. that in turn will decrease performance and fuel economy.
there's a reason (probably previously stated) that youre only supposed to use premium. our engines are higher compression engines which means that each cylinder creates hotter combustion. the grade on fuel (octane) is its resistance to detonation, the higher the grade, the more resistant it is to detonation (knock). when you use lower octane your engine will start to knock(b/c it burns at a lower temp), the piezoelectic sensor will sense this and send voltage to your ecu which in turn will retard timing until it doesnt get any more voltage from the knock sensor. that in turn will decrease performance and fuel economy.
10-22-08, 07:06 PM
#67
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Dutch
You are correct - I meant 87 octane.
I am truthful about mileage figures and lack of problems while using it. Maybe you could detect a difference but I don't seem able to to, and it has been nearly two years on my 97 Gen II.
I am truthful about mileage figures and lack of problems while using it. Maybe you could detect a difference but I don't seem able to to, and it has been nearly two years on my 97 Gen II.
02-22-09, 10:44 PM
#69
I would check for vac leak...my car had some mileage problems, as well as some stuttering in power turns out it was a vac cap that disintegrated after I used it to plug the lines that went to the IAV. That being said, it may need to be replaced again (problem came back).
02-23-09, 05:53 PM
#70
YES YOU SHOULD!!! I hate it when people argue with me to use 87 octane...As if the big glowing neon sign on the guage cluster isn't large enough.
One thing I was suprised about.... My sister's 07 Mustang GT calls for 87 Octane....4.6L 300hp 320ft lbs high performance engine designed for 87 octane??????? I guess it IS just an American car! Hahah
One thing I was suprised about.... My sister's 07 Mustang GT calls for 87 Octane....4.6L 300hp 320ft lbs high performance engine designed for 87 octane??????? I guess it IS just an American car! Hahah
02-24-09, 03:31 PM
#71
wow my car was terrible, i just did a tune up today... i hope my mpg is better than before.
i was getting about 140 miles from f to the warning light... TERRIBLE mpg
I just got back my car put some gas and i made a few trips and the needle went down a tip.
it seems like its doing better, i May put nitrogen in my tires and do a fuel injection cleaning
i was getting about 140 miles from f to the warning light... TERRIBLE mpg
I just got back my car put some gas and i made a few trips and the needle went down a tip.
it seems like its doing better, i May put nitrogen in my tires and do a fuel injection cleaning
02-24-09, 05:42 PM
#72
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i run premium, and fuel system cleaner every 3 or 4 fill ups. and i'm calculating about 18mpg city, and 20ish mpg highway. but i have an extrremly heavy foot, so it could probably get even better mpg. that is if i was ever crazy enough to let someone else drive my baby.
Last edited by 420man361; 02-24-09 at 05:48 PM.
02-24-09, 07:07 PM
#73
Last year i had my valves ajusted due to noise and the tech found that my intake was full of carbon he ground away a lot of carbon and cleaned the throttle body as well and i went from 17 miles to about 22 miles a gallon. He noted that a lot of older ls400 does carbon up pretty much here in california and causes poor gas mileage i also had 7 shims put in for the valve ajustment i think this also made a difference also the car has a lot more pickup since cleaning the throttle body. My last trip to sandiego and back to orange county i got 24.4 miles not bad for an old 1991 lexus with 220,000 miles. PS. I ALSO USE A K&N AIR FILTER THIS WILL ALSO HELP!!!!!
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