I installed a ram cold air induction on my 08 2.4 cobalt and my milage went down from 33 to27 miles to the gallon in a matter of 3 weeks. I live in Iowa and the temps here have been really cold with highs only in the 20s and have been letting warm up for 5 min. before taking off . should I have the computer recalibrated because of the ram air or should it have automatically increased the mileage? Or has the cold dropped mileage that much. Called dealers service departments and they said its normal to drop a couple miles during cold but this seems drastic. any help is greatly appreciated.

 

what brand is it?

 

You already answered your own question.

1. it is colder than normal and it takes more fuel
2. you are letting your car idle to get warm, which takes more fuel.

3. keep your foot off the gas, by "hearing" your intake, you are most likely getting on your car harder than you use to.

 

its a AEM . I drive 40 miles to work most of it highwaysome city . havent gotten onit hard since i seen decrease in mileage . Even on days when high temp is 25 degrees it hasnt increased. Granted i know during winter mileage goes down but 5+ mpg is big drop and it continues to drop 2 tenths every day. no engine light no loss in performance or power actually major increase in power.

 

It has nothing to do with your intake. /thread

 

that statment leads me to belive you have been a little harder on the throttle enjoying your new mod.... milage should increase in the following weeks and also to answer your question yes you should have reset the fuel trims by disconnecting the battery for 15 min or by use of a scanner or HPT

but again not a biggie

 

If you are basing your mileage on your DIC then you are most likely getting an "average" that includes your idle time. Sitting idling the DIC is recording 0 miles per gallon and will keep your average mileage low.

Try clearing the DIC when you are at-speed on the highway and then see what your average is at the end of the day. Better yet, check your MPG when you fill up - miles driven divided by gallons pumped.

 

Keep an eye on your tire pressure. Cold weather will reduce your pressure significantly, and will kill your mileage. The fact that you converted to a C.A.I. is probably coincidental. (And, you may be using the "loud pedal" a little more than you think.)

 

just put on new tires and rims last week pressure good went to 17 inch tires and rims still decreasing. keepin speed at 60 mph on highway and reseting trip and figuring out mileage every tank full without using the DIC ( never trusted them) went from 420 miles to tank full to 330 so far.

 

It's not the intake.

 

Made the statement of increase in power based on the first week i put the C. A. I. in had the CAI in for a month before the decrease in mileage which mad me beleive that I need to have the computer recalibrated for air flow.

 

When installing the intake you should have disconnected your battery which reset the PCM, it learned the new flows when you first started driving. You don't need a tune for an intake.

 

u should be getting better MPG if u lay off the pedal a bit.

 

What size tires did you put on the 17" rims? Could they be less diameter size than the original 15" or 16" wheels? That would increae RPMs per MPH.

Still check the tire pressure -- could be too low due to the air temperature.

Try plugging in an OBDII reader with erase feature and do an "erase" to set all the sensors back to the original settings.

FYI -- disconnecting the battery will not do this, the ECM has an internal power supply.

 

diameter is same as factory made sure of that so that way i didnt change the speedo and mess with the odometer at all and checked tire pressure and is all good .
once again to those saying to stay out of the gas pedal, since i noticed the decrease in mileage i have been keepin a steady pace of 60 mph on highway and most of my 40 mile trip to and from work is highway only 4 miles of it is town driving.
Will have to try reseting the system thanks

 

I say get over it and wait till summer....its hard to get any kinda of fuel milage during the winter...last i checked i was getting 22-24 with my 60's and 2.8 pully so.....