still bad gas mileage

[916drifter]

I still get arounf 17 mpg city and 15 freeway... I have a new 02 sensor, New OEM Intake manifold, NEW OEM Exhaust manifold, and intake and aftercat exhaust. wtf is the problem!!

[GEO]

Lead foot? SHift at lower RPM's.. 1500-2400

[180fan]

ouch man, that new exhaust manifold must have cost you a bundle. Have you tried the rest of the tune up? I would say check/replace the following:

timing = 15 + - 2 degrees TDCPCVignition wiresspark plugs (gap = 1.0 to 1.1 mm)distributor capdistributor rotorturn off AC (I'll explain this later)motor oil (3.5L w/ new filter, =3.2L w/o new filter)oil filter (remember to prep filter element)oil drain plug gasket (once every 7k)fuel filter

well reason I say to check to make sure your AC is off is because your car will have durations where there are higher rpms as a result of having to drive the AC compressor. AKA less mileage. Your timing because if your timing's off, you might step on the gas a bit more to compensate for the less power you may be producing. Checking the spark plugs might also give you an indication of what's going on inside if you have to leadfoot it. Checking the resistance in the ignition wires may also prove useful as a high resistance in the wires will result in weaker spark at the plug, and more likely you'll step on the gas a bit more to compensate.

If you're in an auto, you might want to check to make sure your overdrive is ON for the freeway, as it'll only run you through the first 3 gears, enabling for better accel but you will run in higher rpms lowering your mileage. For in city driving, you may want to drive with overdrive OFF, where acceleration from stop sign to stop sign may be more important and the mileage difference with overdrive ON or OFF is negligable.

[Dattebayo]

When was the last time you checked the alignment? Maybe you got too much toe in the front or something.You know, if you buy cheap gas (87), you dont get as good gas mileage too...

[POS_S13]

i was having bad gas mileage too. recently i changed the fuel filter, plugs, wires, cap and rotor and it made a noticeable difference. its used to use a 1/4 tank to get to werk and now only about a 1/8 tank to get to werk. also keep the rpms down. change your fuel filter especially, its like 10 bucks and only takes like 5 mins to install.

[Japican]

Same here w/ the gasmileage problem. I jus finished all the new installs listed above and i was gonna see my mpg on 91 octane to see if i was gonna get better gas mileage but i jus crashed my car. All that f'n work and money for nothin.

[916drifter]

yea i drive like a granny. i dont have a lead foot at all cuz of the mileage. but ill probably do all those changes... i shift at like 2000rpms. and i use like 89 octane. but how would the spark plug wire,rotor,and cap have to do anything with fuel? and i have a 5spd with a new slave clynder.

[NISTECH]

but how would the spark plug wire,rotor,and cap have to do anything with fuel?

These items are used to ignite the fuel going into the cyl. The ignition of the fuel is dependant on the strength of the spark. if the spark is weak either due to excessive gap on the plug or between the rotor tip and cap electrodes. Or if the duration of the spark is not long enough( how long the spark is present) the fuel may not fully ignite.

When this unburnt fuel passes by the o2 it does not see it. The o2 only registeres oxygen content in the exhaust. When a weak burn occurs more oxygen passes by the o2 since it was not used in the burn process. This in turn sends a lower voltage to the ECM(lean condition).The ECM makes an adjustment to the injector pulse width to compensate for the lean condition adding more fuel to the cyl. untill it gets the o2 voltage to sweep back and forth with a average voltage of 4.5v. This condition would cause a smog machine to pick up a high HC reading since there is a heavy amount of unburnt fuel traveling through the exhaust. A freash cat will do a good job cleaning alot of it up but it can get to the point of max effeciency and allow the rest to go right on through it.

This is why you need to check the condition of your ignition components (plugs,wires,cap and rotor)for fuel effeciency.

[w1ngzer0]

2 words "sea foam" ^_^;;; but you probobly should have kept your old spark plugs in there. Sea foam is all out of my car except the gas can which im still running on 1/2 a tank yippie!! . I also changed the old carbon filled plugs with new NGKs,changed the oil,changed the fuel filter.

But i was getting bad gas i meen the worst gas milage you could get i travel 20-30miles to the next town and 1/2 a tank would be gone.... now only 1/8th is gone. . I still need to do an alignment and check the front left tire cause there is a slow leak

Thats what i did man. I hope the alignment helps my gas milage more. But i might as well get use to it once i turbo my car lol.

[dima]

Regular vr. premium will not give big difference in gas milage read this for more understanding:http://www.epinions.com/content_2618204292.Secondly, I'll agree with some posts above about spark plugs and alignment.One more thing, check your emmitions, it could be you are running too rich.

My 2 cents.