Air Filter: Completely clean & spotless after 9 months??

[Montego Murph]

OK Kids, I have a mystery.

I gassed up today and Fuelio tells me I'm suddenly getting 12mpg, down from a 16. Yeah yeah yeah, I know, if I wanted good MPG I should have bought a Prius, it's a V8, I get it. Yes, it's only a 4mpg drop, but that's also 25%, and even if I were commuting in a garbage truck, I'd want it to be running as efficiently as possible.

Got home and checked the air filter which was last replaced in March, 2017

The 9-month old filter is SPOTLESS. Like, brand new. Not a speck of dust on it. This doesn't make sense to me one bit, and I know for sure that nobody else has worked on my car and maybe slipped it in as a favor or something. It also still has my marking on it -- I write the date with a sharpie or grease pencil.

How is this at all possible? I've spend at least 100 miles driving in really dusty conditions like gravel roads and through agricultural areas with the combines and other machines stirring stuff up.

Any theories or ideas?

 

[keakar]

OK Kids, I have a mystery.

I gassed up today and Fuelio tells me I'm suddenly getting 12mpg, down from a 16. Yeah yeah yeah, I know, if I wanted good MPG I should have bought a Prius, it's a V8, I get it. Yes, it's only a 4mpg drop, but that's also 25%, and even if I were commuting in a garbage truck, I'd want it to be running as efficiently as possible.

Got home and checked the air filter which was last replaced in March, 2017

The 9-month old filter is SPOTLESS. Like, brand new. Not a speck of dust on it. This doesn't make sense to me one bit, and I know for sure that nobody else has worked on my car and maybe slipped it in as a favor or something. It also still has my marking on it -- I write the date with a sharpie or grease pencil.

How is this at all possible? I've spend at least 100 miles driving in really dusty conditions like gravel roads and through agricultural areas with the combines and other machines stirring stuff up.

Any theories or ideas?

there is only one answer, if you were driving in dusty areas and the filter isnt dirty, then the air is being drawn in after the filter bypassing it. this would also explain poor mpg if the air isnt passing over the MAF sensor

first check by eye and hands, then with engine running, get a can of ether and spray around all connections after the filter to the throttle body looking for loose connections. idle will change if you find a leak.

but to be honest a intake tube would need to be completely disconnected to not be pulling air from the filter

 

[Montego Murph]

I agree with what you're saying -- the tube would pretty much have to be completely off to at least not pull SOME air through the filter.

All connections have been checked - I haven't done the propane/ether test but I will later on. (A while back someone taught me if you attach a rubber hose to an unlit propane torch outlet, you can direct a flow of propane and see exactly where an intake or vacuum leak may be.) I even gave each end of the tubing a hard tug but it wouldn't even budge.

I think what I'll have to check next is to see if there's something on the atmosphere side of the filter (where it goes into the body) that is both blocking airflow and acting as a "prefilter" of sorts. Like for example maybe there's a bird's next or wad of paper towels that somehow got in there and the moisture is grabbing the dirt and impairing air flow.

Oddly enough there's no perceived power loss which makes me think the above theory is flat out horsefeathers, but I'm going to check anyway so all my bases are covered.

 

[theoutbackdream]

My only guess would that be you're bypassing the intake system and getting air from somewhere else, which would result in your AFR running lean.

However, since you said you aren't noticing drastic performance losses, i'm not sure. Or maybe, you always had an intake leak somewhere, and didn't notice it since you always had a problem.

 

[keakar]

I agree with what you're saying -- the tube would pretty much have to be completely off to at least not pull SOME air through the filter.

All connections have been checked - I haven't done the propane/ether test but I will later on. (A while back someone taught me if you attach a rubber hose to an unlit propane torch outlet, you can direct a flow of propane and see exactly where an intake or vacuum leak may be.) I even gave each end of the tubing a hard tug but it wouldn't even budge.

I think what I'll have to check next is to see if there's something on the atmosphere side of the filter (where it goes into the body) that is both blocking airflow and acting as a "prefilter" of sorts. Like for example maybe there's a bird's next or wad of paper towels that somehow got in there and the moisture is grabbing the dirt and impairing air flow.

Oddly enough there's no perceived power loss which makes me think the above theory is flat out horsefeathers, but I'm going to check anyway so all my bases are covered.

if the intake tube looks ok then maybe a cracked intake or bad intake gasket but then i would think it would not be running very good at all.

maybe you just didnt do enough to get the filter dirty or is is just lightly dirty a slight shade of color and nothing is wrong but :shrug:

to fix the bad mpg, i would clean the MAF sensor and check the charcoal screen isnt clogged up, it sits inside the top cover of the box for the filter. i just ripped mine out and the engine runs smoother now.

you absolutely sure the wife/girlfriend didnt stop somewhere to get a flat fixed or something else done on it and had the air filter replaced while it was there and just never told you???

also my last wild thought, could the air filter box have been left just sitting there and not snapped down letting it suck air in that way?

.

 

[Inv4drZm]

Any fine dust in the intake box at all, before the filter? Usually mine has some, though I've never cleaned it so maybe it's just been there the entire time and isn't increasing.

 

[tenebs]

to fix the bad mpg, i would clean the MAF sensor and check the charcoal screen isnt clogged up, it sits inside the top cover of the box for the filter. i just ripped mine out and the engine runs smoother now.


.

I have a 2004 V6 am I'm thinking about also removing the nonreplacable charcoal filter that is between the air filter and intake. I have close to 200k miles and I can't imagine that filter is doing anything but reducing airflow by now. I see above you mentioned removing it. Have you had any issues, problems with emissions, etc.? I also cleaned the throttle body and made sensor and changed spark plugs somim going to reset the efi fuses so the computer can reset to the new plugs and cleaner intake components.

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