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Mileage...

M

mick777wauchope

New member
I know there are tons of posts about fuel mileage, but I'm so confused. My car must be burning really rich because I am a light footed driver, and I am getting 13 mpg. I can smell strong gas from my exhaust seconds after startup. How do I improve on this stuff? I have a 2000 Grand Prix GTP.
 


First, check for any CEL lights or anything obviously wrong. Make sure your tire pressure is high enough. Also, are you running your A/C? That can hurt your gas mileage as well. If you're using your DIC to calculate gas mileage, don't forget to reset it. Also, going 60 on the expressway gets you better mileage than going 70 or higher. I can generally get 35MPG highway, 17MPG city (I like to take off from lights once in a while so you can probably do better.) I think the biggest key is maintenance.
 
I drive very light in the city, and get 13... My SES light is on, only with the gas cap code. Everything else is fine. Replaced MAF, CAI, new plugs and wires, idk what to do...
 
with out the gas cap on correctly pressure is not building up properly and fumes could be escaping witch is fuel
 


mick777wauchope said:
I drive very light in the city, and get 13... My SES light is on, only with the gas cap code. Everything else is fine. Replaced MAF, CAI, new plugs and wires, idk what to do...
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you could have a bad evap or purge solenoid, i think thats what its call, if a new gas cap dont fix it.

if you dont hit the highway much or at all, and drive around down all the time, like me, so mine drops as low as 12 mpg on the mpg average. even tho the instant it always up over 25 or higher. and im not hot rodding around town. pretty light on the gas myself.
 


Fuel smell from tail pipes?
That's not normal, especially if you have a catalytic converter.

Pull the oil dipstick and see if it smells like fuel.

You may have a dead injector but this should set a misfire code P030X. X would be cylinder number 1-6.

You said you put a new O2 sensor? Seems like you replaced the down stream sensor. How about the upstream sensor that is in the rear manifold?
 
Rico said:
Fuel smell from tail pipes?
That's not normal, especially if you have a catalytic converter.

Pull the oil dipstick and see if it smells like fuel.

You may have a dead injector but this should set a misfire code P030X. X would be cylinder number 1-6.

You said you put a new O2 sensor? Seems like you replaced the down stream sensor. How about the upstream sensor that is in the rear manifold?
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How much would that o2 sensor cost? Is it easy to replace?
 
I have replaced the gas cap, and Im scared of running seafoam through my gtp because I don't wanna strip the rotors. I have ran it through gas though.
 


i dont recall the 2000 having the gas cap code. what is the exact code number you have.

ive noticed alot of people check codes and have it be emissions related and just brush it off as a "gas cap code" when it has nothing to do with the gas cap.
 
I'd run a scan tool thru it and check your long term fuel trim. If your o2 sensor is bad and it reads lean it will cause the engine to add more fuel. It can be up to almost 20 off before it will set the check engine light. it should be around 10 or less preferably
 
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