If air flow is increased by installing a K&N in my 95 f150 5.0L would the MAF and oxygen sensors detect the extra flow and oxygen and tell the ECM to increase fuel output from the injectors to balance out the air to fuel ratio thus reducing gas mileage.Any thoughts on this. </pre>

 

I see what your getting at and used to wonder the same thing. I think in theory it would be true. I do know one thing. I've tried KN intakes and drop in filters on numerous vehicles, and will never use them again. My truck got worse fuel economy with both. I'll stick with the stock setup with the 4.9/7.5 lower tube and a Motorcraft filter.

 

K&N's are a double edged sword. They have the potential to get you better and worse gas mileage. Best way it was ever put was by my boss years ago when we put a K&N filter and intake kit on his 97 F150 2wd, single cab, short bed, 4.6 auto. If I stay out of it I get better mileage than I did before, If run it hard, I get worse mileage than before. Because it was an intake kit, it made it sound really aggressive and made you want to drive it harder. So if you can put it in and drive it normally, like you're looking for best fuel economy, you'll get it. I have also noticed this in any of my 4cyl or v6 fwd cars as well.

 

Mine didn't get better under normal driving either. The same was true with our 97 Mustang Cobra.

My friend had his mass air sensor fail shortly after installing one of these stupid things too.

I did notice an inherent problem with the FIPK for MAF trucks. It doesn't seal up at the throttle body. I've seen this on every one I looked at.

I'd rather use a non oiled filter like AFE or AEM. I don't know how well they filter dirt though.

 

I put an AMSOil filter in mine (non oil type) and it seems to work well, still not sure if i will be keeping it or not tho...better then the K&I one i had tho, makes a better fit IMO (in box)as the K&I seemed a tiny bit loose...

 

It seems to me that for modern vehicles normal driving (ie rarely loaded down and/or WOT) with the factory intake & exhaust is as good or better mpg's than the same truck with intake kit and bigger exhaust. They do, however, provide better power & efficiency under heavier loads and other situations of more throttle. For me that's up a hill with a cord of fireword in the back. The enhanced intake & exhaust (& Jet chip) help my little 5.8L get the loaded F350 home quicker and more efficiently.

 

It won't be because the stock airbox isn't a bottleneck on these trucks, but nonetheless..

If there is an increase then yes.

The sensors don't tell the ECM to do anything, they just provide input and the ECM decides if the injectors need more fuel or not.

Increased airflow through a motor will increase power output but fuel milage only suffers if you're using that extra power.

 

I'd dump the Jet chip and just bump up the timing a bit.

 

Everything Conanski said makes sense, and is how the computer and sensors work together.