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Alright, it seems lately, a lot of people has been having gas crisis...but I got the worse of it all. My Zx3 has mild mods to it and lately, my gas mileage has been getting real bad. Used to be I get about 300 miles per full tank, then it went down to 250 with some mods. Then it went to 210 about two months ago...now for the past three weeks, I've only been getting 185 miles per full tank...what's up with that?

I've changed spark plugs, wires, filters and every possible element I can think of. What could it be...it's not a heavy foot also because my 350z gets better mileage than my Focus.
 

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I can really use some info on this same subject...about 2 weeks ago i put a full exhaust(header,flex,cat-back) on my zx3 and ever since that my MPG sucks...and i dont have the Heavy foot syndrome, i shift everytime the little yellow up arrow light comes on.
 

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with the mods on your car have you been using premium fuel?
 

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Yeah I have had this problem too....I dont know, maybe they are doing something to the gas to make it burn faster so you have to buy more...I dunno.....I didnt even get 20 mpg last tank...under 200 miles on a tank
 

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Ditto on the mpg loss. Added the shorty header, hi-flo cat, flex, and exhaust to a FC intake. I didn't really notice a change in the range, but switched to premium to settle the "lope" that developed at idle. The lope is gone, but the mileage has been steadily decreasing. I expected some "drop" with the tire swap and the different sizing, but it continues to go down. Any idea if the SCT chip would help with this?
 

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your answer lay within
sorry Bur but i dont have Leadfootitis ...Spelling?? and yet my gas is getting sucked from my car...i still use regular gas...should i use Premium?
 

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I have all the basics done to mine as seen in my sig. I roll with the cruise on. I put her in 5th gear as much as possible. Im lucky to hit 27or28 mpg. It sucks. For a 4-cyl I would think it would be a lil better. Especially with the exhaust and intake on it.
 

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I drive my car like it was stolen and get close to 300 miles out of a tank. What sort of A/F mixture does your car have? It might be running pig rich.
 

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If I'm cruising, I can still get 30mpg... 4-2-1/flex/exhaust/intake/SCT. Something a lto of my friends don't understand is that just because you're in a high gear doesn't always mean better mpg..when you havta hold it to the floor in 5th because you're only going 35mph, you waste gas. Smooth driving and maintaining speed are the best ways I've found to maximize fuel economy.
 

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the O2 sensors have A LOT to do with gas mileage. When you guys are replacing headers, etc...what happens to your O2 sensors? (dunno, cause I have an SVT)....do you use an eliminator? Or the same sensor? I would get a dyno and see what the A/F is and perhaps get a chip to lean things out.
 

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I dont beat my car to bad but I do a lot of passing and do get on it once in a while and I am still getting 325 to a tank.
 

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Well I think I've leaned my tune out a little bit by adding the extra boost and not changing the tune. I have to send my data log's to Randy so he can tell me. Still no pings.
 

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couple things could be the culprit
1.what kind of spark plugs did you buy
2.how long has it been since you've cleaned out the carbon in the manifold and on the valves.

I have to clean my car out about once every six months and it still have the stock cams. with aftermarket cams you may have to do it often or start putting the lucas fuelinjector cleaner in the tank every month.

3.o2 sensors
 

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Put chevron techron in a full-tank of gas, drive the p*ss out of it for 10~15mins (longer is better), and see if it improves.

my car gets worse and worse mileage if i keep driving like an old man with those 2.5 mile commutes; the above method brings mileage back to normal. Maybe your car needs a beating once a while like mine does.
 
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