speed76demon

I mean like 8-10mpg?? its got new plugs,wire,02's,opti,fuel pump. It runs real strong and i'm not sure if i filled it up all the way last time but it just seemed like the mpg went down when i filled it up today. I mean i didnt even think i could get that bad if i ran 150 all day long well whatcha think??

RamAir95TA

Possible causes for poor gas mileage:

• Defective O2 sensors.
• Exhaust leak.
• Fouled plugs.
• Bad optispark/ignition components.
• Lead foot syndrome.
• Underinflated tires.
• Low gears (numerically lower).
• Poor or incorrect PCM calibration/programming.
• Faulty injectors.
• Torn fuel pressure regulator.
• Emergency brake left on.
  

...just to name a few.

JoeliusZ28

My mileage drops nearly that low in 25 mph and under city driving. But if your talking 45-65 range then you should be getting at least 15 mpg. You are using minimum 92 octane I hope. Something to check: When was the last time your fuel filter was replaced? An old/clogged filter can hurt mileage. Make sure your air-cleaner is clean too. Synthetic oil increase my mileage by about 1-2 (not sure how but it did) Just a few basics.

speed76demon

well i drove 60miles all in a town of a 35mph zone and its a small town so a lot of stop an go

Zack

running the AC all the time

RENE95Z

Check your MAP sensor. Usually the culprit when it comes to a drastic loss in gas mileage. Of course the other things stated above will contribute.

shoebox

I was gonna suggest MAP, too but usually performance suffers as well.

OldSStroker

Don't use the fuel gage to check mileage. Top off the tank, use at least 3/4 of it and top it off the same way. Divide miles run by gallons. That will give you a realistic idea of actual fuel mileage.

BTW 8-10 mpg at a constant 150 would be exceptionally good.

Van5150

Do we know how much MAP sensors cost ?

shoebox

Depends on where you get one. ~$35 May be twice that at dealer retail.