what causes a car to run rich?

[95firebird3.4]

i just did a fuel tune about 2 months ago i don't know what could be wrong i normally get 400 miles on a full tank of gas and now i am only getting 288. what should i check and what not to get my gas mileage back up.

[josh98bird]

Re: what causes a car to run rich?

change in temperature / the air entering your engine and how you drive the car can change your gas mileage alot.

[Sean_99_3.8]

Re: what causes a car to run rich?

400 miles? seems high to me but i could be wrong.
to much fuel with not enough air.
you could change back to the stock tune.
why did you need to change your mixture?

[bluovlh8er]

Re: what causes a car to run rich?

x2 i get just under 300 miles per tank (98 3.8).

[95firebird3.4]

Re: what causes a car to run rich?

400 miles? seems high to me but i could be wrong.
to much fuel with not enough air.
you could change back to the stock tune.
why did you need to change your mixture?

i dont need to change it i just dont no y i am getting such bad gas milage compared to what i used to

[slow6]

Re: what causes a car to run rich?

many reasons it could run rich including (but not limited to):
bad o2 sensors
exhaust leak
bad tune
bad maf

[95firebird3.4]

Re: what causes a car to run rich?

many reasons it could run rich including (but not limited to):
bad o2 sensors
exhaust leak
bad tune
bad maf

where should i start

[auto666]

Re: what causes a car to run rich?

tune is where to start

[vanbibber]

Re: what causes a car to run rich?

tune is where to start

many reasons it could run rich including (but not limited to):
bad o2 sensors
exhaust leak
bad tune
bad maf

bad tune is out of the question, its a 3.4
bad maf ditto its a 3.4, they are SD cars.

when was the last time you did a tune up? replace plugs and wires and the o2 sensors use ac delco o2s not bosch.

[auto666]

Re: what causes a car to run rich?

i understand its a 3.4 but he said he did a fuel tune so ie change back what ya changed

[vanbibber]

Re: what causes a car to run rich?

im assuming a hypertech or jet chip then? even so your gas mileage shouldnt be effected that much.

[95firebird3.4]

Re: what causes a car to run rich?

bad tune is out of the question, its a 3.4
bad maf ditto its a 3.4, they are SD cars.

when was the last time you did a tune up? replace plugs and wires and the o2 sensors use ac delco o2s not bosch.

lol i am sry that was supposed to me full tune up not fuel lol. so that answers the plugs and wires. i dont think i have ever change the o2 sensors where are they located

[vanbibber]

Re: what causes a car to run rich?

one in each exhaust manifold. the drivers side is pretty easy to get to, the passenger side is a fight. you'll have to do them from underneath the car. just look at the manifolds and you'll see them if you follow them down under the car. id assume theyre the factory ones so be prepared for them to be in there pretty good.

[stlunatics2oo3]

Re: what causes a car to run rich?

i got mine from the top each side but i don't have big fore arms.

[Camaro Dom]

Re: what causes a car to run rich?

i get about 350 to a tank ('00 3.8 A4 112k miles)
but then agian, almost ALL of my driving is highway, and i just hit the CC at 70 and cruise, no a/c this time of year either.