High flow air filter problem

[wingzam]

I installed a high flow air filter on my 87 2.9 and my fuel economy dropped 2-3 mpg.A guy told me the increase in air causes the computer to add too much more fuel to the fuel air ratio.Is this correct?

 

[Beanmachine7000]

The air filter isn't pushing anymore air in is it? No... The engine only sucks in as much air as the flow characteristics allow... You can run with no air filter and it will still suck in the same amount (which is why high flow filters don't work, the motor still flows the same amount of air)... Therefore, there is another reason for your fuel mileage problems...

 

[baxtej44]

The air filter isn't pushing anymore air in is it? No... The engine only sucks in as much air as the flow characteristics allow... You can run with no air filter and it will still suck in the same amount (which is why high flow filters don't work, the motor still flows the same amount of air)... Therefore, there is another reason for your fuel mileage problems...

i'm not all exactly sure, but this sounds very convinving.


i would just say it may be considered high flow because of surface area or something... i mean i would guess that it would be harder for your engine to suck air through a millimeter filter versus a standard one...

but i would check if you accidentally forgot to hook something back up? or hook it up to see if there are any codes coming up... obviously something isn't right.

 

[Beanmachine7000]

i'm not all exactly sure, but this sounds very convinving.


i would just say it may be considered high flow because of surface area or something... i mean i would guess that it would be harder for your engine to suck air through a millimeter filter versus a standard one...

but i would check if you accidentally forgot to hook something back up? or hook it up to see if there are any codes coming up... obviously something isn't right.

It's high flow characteristics come from the size of the holes in the filter element... All RBV's use the same air box assembly, from the 2.3L-4.0L... If that filter is capable of feeding a 4.0L with adequate air, it is almost 2x the capacity of what the 2.9L needs... So, the only thing a high flow filter does is suck in more DIRT...

 

[wingzam]

Thanks for the replies.Will take another look and see if I screwed something up.

 

[RustedRanger]

wing did you unhook the battery and let the computer clear out? The computer can't adjust for improvements. It can only adjust for running worse like as the tune up wears out. Recently I put Restore in my oil and added Lucas fuel treatment and it started running worse until I unhooked the battery for awhile. I have a high flow filter hooked up to my stock air intake tube and I have been getting an average of 22 mpg.

 

[Area 52]

I installed a high flow air filter on my 87 2.9 and my fuel economy dropped 2-3 mpg.A guy told me the increase in air causes the computer to add too much more fuel to the fuel air ratio.Is this correct?

What kind of filter is it...a new panel filter in the stock air box? I suspect you installed a cone-type, oil-coated filter. I lost HP and fuel mileage in my BMW with a replacement K&N panel filter in the stock air box. I lost a little over one mpg and low-end torque with a CAI K&N system in my F150/5.4liter. Also, excess oil on these types of filters will contaminate the MAF sensor and require cleaning. Excess dirt also passes through...google it and you'll find a lot of supporting data. Can't think of any car manufacturer that installs em either.

 

[Bob Ayers]

The air filter isn't pushing anymore air in is it? No... The engine only sucks in as much air as the flow characteristics allow... You can run with no air filter and it will still suck in the same amount (which is why high flow filters don't work, the motor still flows the same amount of air)... Therefore, there is another reason for your fuel mileage problems...

+1
...................

 

[RustedRanger]

Its a cone type filter. I believe alot of the oiling issues are caused by over oiling. My dad runs a K&N on his 92 Chevy 4X4 5.7L since right after he bought it new and the last time I had the filter lid off it had over 100,000mi. and had beed driven out west where it is dusty several times,the TBI looked brand new inside and he never cleaned it,he only runs fuel injector cleaner. It's all stock except for the filter and a flowmaster cat back exhaust and he avgs 20 mpg highway.

 

[Bob Ayers]

Its a cone type filter. I believe alot of the oiling issues are caused by over oiling. My dad runs a K&N on his 92 Chevy 4X4 5.7L since right after he bought it new and the last time I had the filter lid off it had over 100,000mi. and had beed driven out west where it is dusty several times,the TBI looked brand new inside and he never cleaned it,he only runs fuel injector cleaner. It's all stock except for the filter and a flowmaster cat back exhaust and he avgs 20 mpg highway.

The point is the OEM filter & intake will flow way more air than the engine can pull, so there is no advantage to the K&N. Known fact, the K&N will pass more dirt, AND OIL, so all the K&N will do is cause problems.

 

[holyford86]

The point is the OEM filter & intake will flow way more air than the engine can pull, so there is no advantage to the K&N. Known fact, the K&N will pass more dirt, AND OIL, so all the K&N will do is cause problems.

+1

 

[baxtej44]

so i'd be better off just getting a new air filter every tune up (3k miles or so) that is a panel type and keep the original air box too?


completely opposite everything i thought lol.

 

[Beanmachine7000]

so i'd be better off just getting a new air filter every tune up (3k miles or so) that is a panel type and keep the original air box too?


completely opposite everything i thought lol.

Yes...

 

[Bob Ayers]

so i'd be better off just getting a new air filter every tune up (3k miles or so) that is a panel type and keep the original air box too?


completely opposite everything i thought lol.

You should be able to go 15K - 20K miles on the OEM paper filter.

Tune up every 3K?
Even back in the days of leaded fuel, point-type ignition, non-platinum plugs, and carbs, a tuneup wasn't needed every 3K.

 

[Beanmachine7000]

The only things that is needed every 3K miles is oil change, and with today's detergent oils and synthetics you can push that out to 5k-15k depending on what kind of oil you get... n