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Just installed a CAI however I have noticed a loss of fuel milage about 1.5 miles per gal. Not sure as to why ......any suggestions.....thanks in advance......... :gr_patrio
 

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Did you relocate your IAT sensor to the CAI? Regardless whether you did or not, your IAT sensor is reading the cold air coming into the intake and it's telling the PCM to richen up the fuel mixture. With a CAI, you are sacrificing mpg for extra hp. Just the nature of the beast. I used a CAI on my R/T and my mpg took a crap. Replaced it with a 14" K&N filter and it actually gained some mpg over stock and the torque and hp are still there. My 5.9L is getting 16.5 in town driving and 18.5 on the highway. I'm very pleased with those numbers.

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Yes the IAT is now on the CAI. Are you saying to leave the CAI in place but add a larger diameter filter to the end of it........................that would give me more and colder air wont it.......................can I reset my comp by disconnecting the battery ?
 

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mimmo said:
Yes the IAT is now on the CAI. Are you saying to leave the CAI in place but add a larger diameter filter to the end of it........................that would give me more and colder air wont it.......................can I reset my comp by disconnecting the battery ?
With the IAT in the CAI, it is reading the colder air thus it's telling the PCM to richen up the fuel mixture to the injectors thus giving you more hp but at the same time causing a drop in your mpg. The size filter you have is good, no need to change it. Reseting the PCM will not be necessary. You have to decide which one you want, mpg or hp. If you want hp, leave the IAT where you have it now. If you want mpg, move the IAT back to the intake manifold. The PCM will make the adjustments on it's own.

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I dont know much about vehicles per se but i do have a commerical pilots lic and am currently working on my aviation mechanics lic, but we are told and do lean are mixture (amount of fuel) for recip (prop engines) as we get higher or if we operate in cold (or less dense air) so my question is why would you burn more gas if the air coming in is colder if it is less dense and requires less fuel in the fuel/air mixture? I am asking to expand my own knowledge wikipedia gets really deep into rich and lean subjects.
 

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The fuel mixture is automatically adjusted by the PCM programing according to the incoming air temperture (IAT sensor). The colder the air, the richer the mixture, the warmer the air, the leaner the mixture.
 

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MatrixMan said:
x2 :tup: CAI is a good thing...
I see it as a "catch 22" kind of thing. Colder air = more HP due to the richer mixture. Warmer air = more MPG due to the leaner mixture. So I guess it really depends on a persons preference.
 

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The PCM will only add more fuel at WOT... In all other part throttle positions your O2 sensors are used and will keep the AFR nailed to 14.75:1. At WOT the O2 Sensors are no longer used and this is when the colder air effects the amount of fuel.

At least I know this holds true to the (2002-UP) and only assume the same for later engines. It could be different for him but If I remember correctly his PCM is set up to do the same thing.

So his bad fuel economy are most like due to his foot position rather then his sensor location.

You need to remember that any time you increase the ability for your engine to consume more air... you also increase the engines ability to consume more fuel. Light throttle driving SHOULD yield better MPG's but your WOT will consume more fuel... This is why many people who add intakes see similar results... the first few days they tend to drive harder attempting to "FEEL" the new POWER... this in itself is bad for fuel economey.

DangyLimited said:
I dont know much about vehicles per se but i do have a commerical pilots lic and am currently working on my aviation mechanics lic, but we are told and do lean are mixture (amount of fuel) for recip (prop engines) as we get higher or if we operate in cold (or less dense air) so my question is why would you burn more gas if the air coming in is colder if it is less dense and requires less fuel in the fuel/air mixture? I am asking to expand my own knowledge wikipedia gets really deep into rich and lean subjects.
Cold air is DENSE air, this means there is MORE air per Square inch. With the additional air you need to add an appropriate amount of fuel.

I don't see why they would LEAN out for cold air... Unless they are intentionally running on the RICH side for take off. I have heard of Pilots leaning out the AFR to gain better fuel economey though.



SPEED SAFE, AIR RAM
 

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AIR_RAM said:
The PCM will only add more fuel at WOT... In all other part throttle positions your O2 sensors are used and will keep the AFR nailed to 14.75:1. At WOT the O2 Sensors are no longer used and this is when the colder air effects the amount of fuel.

At least I know this holds true to the (2002-UP) and only assume the same for later engines. It could be different for him but If I remember correctly his PCM is set up to do the same thing.

So his bad fuel economy are most like due to his foot position rather then his sensor location.

You need to remember that any time you increase the ability for your engine to consume more air... you also increase the engines ability to consume more fuel. Light throttle driving SHOULD yield better MPG's but your WOT will consume more fuel... This is why many people who add intakes see similar results... the first few days they tend to drive harder attempting to "FEEL" the new POWER... this in itself is bad for fuel economey.

Cold air is DENSE air, this means there is MORE air per Square inch. With the additional air you need to add an appropriate amount of fuel.

I don't see why they would LEAN out for cold air... Unless they are intentionally running on the RICH side for take off. I have heard of Pilots leaning out the AFR to gain better fuel economey though.



SPEED SAFE, AIR RAM
Thanks, i also cracked open one of my old flight books. The reason we lean our mixture is one to have better econ, but also because the air is less dense because pressure decrease as you go higher.
"Our calculations are further complicated by altitude and temperature. As we climb, the air “gets thinner”. The density of the air decreases; the distance between individual molecules of oxygen increases. For a given volume of air the actual weight of available oxygen decreases with altitude. Temperature has a similar effect on air density for the same reason: increased temperature results in reduced air density. So my statement earlier was incorrect about cold air being less dense i was taking only part of the reason (decrease in pressure or thinner air) but we do it to keep the ratio as now the air is thinner therefore we need less fuel, of course if we add supercharger alot of that is fixed.

Thanks for the knowledge guys
 

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I added an intake last week and i get better econ while at highway speed, noticed .5-1mpg increase at my 70-75mph range but like you said pedal position is everything because the roar of my D is quite intoxicating
 
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