Hey guys, this has probably been asked before..
i recently got my 2nd cobalt (upgraded from 2.4L to 2.0 LNF and loving it)
the car came with the cold air intake from K&N. since ive been driving it
ive been getting 20-20.5MPG or 11.4-11.8L/100Km
when i look at the forums and see people getting 25-30mpg that kind of bothers me and makes me wonder why.
i live in Vancouver and temperatures here rarely go below 0 (10C or 50F)

could the intake be throwing the fuel trims off and therefore running little rich? or the winter fuel mix? i only fill up at shell with 91...

thought i would ask here before going to a shop and asking for a tune.

thanks

 

driving habits and even with just that k&n intake your fuel trims will go all crazy haha. def get a tune and youll be good to go

 

Yeah if you dont have a tune then it will screw up your fuel trims. And yeah driving habits play a big part. Also the mpg the car gives you may no be to accurate well depending how long you have with the car after some miles it should be getting better at calculating your mpg

 

How many miles are on the LNF?

 

could be the winter blend of gas and the fuel trims being all messed up

 

Throwing the fuel trims off will not effect fuel mileage (significantly, unless they're like -25%), the trims being off is the ECU saying I want to be as close to stioch as I can so I add this much fuel consistently from my base tables, then the STFT makes small adjustments to keep it in check. Your right foot will affect fuel mileage more than trims being off.

 

i know when i threw my k&n sri on my fuel trims were 15-20% off and i saw my mpg drop but not a lot, but enough for me to notice. but yes that right foot has a lot to do with everything mpg lol

 

thanks guys, the car has 65k (40k miles) on it.

and i dont drive like a crazy man..always shift and try to keep rpm to 2k but i do sometimes like to feel the power and do an occasional rip here and there

just wondering if the cai would play a big role on the trims
maybe that is the factor who knows.. ill have a look at the trims and will keep you posted.

 

it could be the bad fuel too for the winter blend, but double check your fuel trims and possibly change your plugs and maybe run some seafoam through it as well to clean things up a little. i know the seafoam wont clean the valves but i usually run some through ever so often

 

That should throw a code, iirc the fuel trim code throws at +-15% which that would cause a bit of a drop.

Try shifting closer to 3-3.5k if you're shifting at 2k your ******* it

 

I generally throw some in the oil right before a change, and the rest in the tank. If it does anything on these cars I'm not sure, I know on old carb'd equipment it made a huge difference and prevented any fuel varnish from developing.

 

i didnt get a code but my buddy did for that exact reason lol

i run some through the valves and then the gas tank and it burns a lot of **** out of it lol

 

umm wouldn't shifting at higher rpm cause more fuel consumption??

 

yes and no, as long as you stay out of boost when your driving youll get decent gas mileage running up to 3-4k doesnt mean you have to hit boost at all, slowly get on the gas instead of bogging down

 

This, you make more torque just outside of 2k which is more efficient use of fuel to accelerate yourself forward, ******* it takes longer to get to speed which in turn consumes more fuel. Fuel mileage stays pretty similar below 3k for cruising, shifting at 3.5-4k wont effect much since its so little time spend there

 

basically just something easy to remember is if your in boost your using fuel no boost not as much fuel lol

 

alright, thanks guys appreciate your input on this!!
ill keep posted