Effects of backwards air filter?

[Pat in Speedway]

Hi all...My stepdaughter has a '95 Geo Prizm with 168k miles that she's had for a little over a year. The fuel mileage EPA is 26 city, 30 highway. She's been complaining (as 19 year olds like to do) about always having to put gas in it. I filled it up 2 weeks ago and in that time she'd put on about 90 city miles. I took it out tonight and the gauge was between 1/2 and 1/4. I filled it with a whopping 4.228 gallons (21.6mpg). I figured something wasn't right here. So when I got home, I looked over the plugs and wires to make sure they were all secure. THEN I came to the air filter. Keep in mind, the only maintenance done since we've had it was an oil change. So I popped off the air filter housing and much to my surprise the filter was facing the wrong direction: the side of the filter with the pleats was facing up instead of the "chicken wire" side facing up. After I put it in the correct direction, I decided to see what this thing would do with highway miles. So, I drove around the interstate loop around Indianapolis to check if it made a difference. Upon refilling after that trip of 63.7 miles, it took a mere 1.791 gallons to fill (35.6mpg). I had the cruise stuck on 60 the bulk of the trip.

I told her tonight to stay off the interstate and when the trip odometer gets to around 90 miles, to let me know so I can check the mileage and compare it to that 21.6 all-city miles tank.

So here's my question: What, if any, might a backwards air filter have on fuel economy? Was the engine being starved for air, or would it still flow correctly even if it was backwards? Thoughts appreciated!

 

[salvageyardteen]

They must have worked hard to get in in backwards.

 

[Steve S]

Probably reversing the filter cleaned off the dirt .

 

[Pablo]

HUH?

 

[rriddle3]

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...So here's my question: What, if any, might a backwards air filter have on fuel economy? Was the engine being starved for air, or would it still flow correctly even if it was backwards? Thoughts appreciated!

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OMG, everybody knows a backward air filter will suck all the air out of an engine!

 

[surfstar]

By re-using that filter and turning it around, weren't you afraid of the engine sucking dirt from the pleats? I'd replace that thing for $10.

 

[XS650]

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By re-using that filter and turning it around, weren't you afraid of the engine sucking dirt from the pleats? I'd replace that thing for $10.

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That's comparable to turning your shorts inside out and wearing them again instead of washing them.

 

[lazaro]

that's one oil sample I would love to see.
sillycone.

was that filter put in new like that? I hope so.

 

[Pat in Speedway]

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that's one oil sample I would love to see.
sillycone.

was that filter put in new like that? I hope so.

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As far as I can tell, it was put in new that way. A couple of the pleats on the end were crunched a little. As if I didn't have enough to do, I suppose it'd be better if I got a new filter this weekend and the oil. Lord knows I'd never hear the end of it if something goes wrong with it.

 

[Camu Mahubah]

Get that filter out of there...please install new filter...Prizm to good of a car to destroy...all that time it was filling with dirt now you are sucking it in! Change oil too!

 

[mechtech2]

It sounds like the filter was in correctly, to start with.
The metal grate is for backing strength, and seems to have been oriented properly.

 

[Steve S]

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Quote:

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By re-using that filter and turning it around, weren't you afraid of the engine sucking dirt from the pleats? I'd replace that thing for $10.

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That's comparable to turning your shorts inside out and wearing them again instead of washing them.

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works for me!!!!!

 

[Eddie]

+1 for mechtech2

 

[Pat in Speedway]

According to the manual, and the illustration with it, I reinstalled it the correct way...chicken wire facing up. And, upon installing it that way, it fit into its slot...just like it's supposed to.

 

[pcoxe]

One of my in-laws somehow installed a used fuel filter backwards once. The carb instantly went into fuel injection mode! We had to disassemble the carb to clean out the silt and replaced the needle and seat. A backwards used air filter problem probably won't show up quite as fast, but it makes me cringe to think about it!

 

[widman]

Backwards should normally not change the flow rate, but turning it over will definitely put a lot of dirt into the engine. Normally the wire is on the outlet side, but a lot of filters have it on the inlet side, others use no wire.