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Built in air filter in air filter box - rev drop issue

3221 Views 29 Replies 3 Participants Last post by  rich_d
I have another built in filter between the MAF and replaceable air filter attached to the air filter box cover. It looks pretty dirty. Is this something hat should be replaced or cleaned? My air filter still looks clean.


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most everyone is just removing it. i have removed it from all 4 of my toyotas. i just take the MAF sensor out every 50k miles or so and clean it with MAF spray and put it back in. just to clarify, this is that white screen looking filter that is attached to the air filter cover so to be directly over the air filter?
most everyone is just removing it. i have removed it from all 4 of my toyotas. i just take the MAF sensor out every 50k miles or so and clean it with MAF spray and put it back in. just to clarify, this is that white screen looking filter that is attached to the air filter cover so to be directly over the air filter?
Yes it is. It is attached to the filter cover below the MAF. Do you just pry it out? It looks like it’s plastic welded to the air filter cover.


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Yes it is. It is attached to the filter cover below the MAF. Do you just pry it out? It looks like it’s plastic welded to the air filter cover.


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yes.. just pry it out, it will break,, all of mine have. and i just throw them away. you can search on the forum and other discussion boards about the topic. i found one still in the 2008 matrix i bought last april and removed it. it was nasty dirty..
some people have been successful at not breaking it while removing it.
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Received my "ARES" CAI via FEDEX today. Hope this cold air intake is any good. We shall see soon enough.
BTW is there anything to be gained by removing the filter cover below the MAF, specifically on my '16 Corolla S?
Received my "ARES" CAI via FEDEX today. Hope this cold air intake is any good. We shall see soon enough.
BTW is there anything to be gained by removing the filter cover below the MAF, specifically on my '16 Corolla S?
people say it helps. my cars seem a bit peppier with it gone.


just some info from google search. but it is what you are asking about


just some info from google search. but it is what you are asking about
Thank you. I wasn’t using the correct keyword for this filter when I Googled it and couldn’t find info on it.

It’s basically a charcoal filter to filter blowby gas exiting the air intake when engine has just shut down. I don’t really see the point of this since the throttle valve is closed already.

Anyway I’m gonna try to remove it this weekend. I hope it removes the rev dip I experience when pressing the gas from idle.

PS. I’ve got almost 160k miles on this filter and it’s really dirty. I don’t know why this isn’t a replacement part since it restricts airflow.


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Thank you. I wasn’t using the correct keyword for this filter when I Googled it and couldn’t find info on it.

It’s basically a charcoal filter to filter blowby gas exiting the air intake when engine has just shut down. I don’t really see the point of this since the throttle valve is closed already.

Anyway I’m gonna try to remove it this weekend. I hope it removes the rev dip I experience when pressing the gas from idle.


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just make sure you aren't in a state that will check that each year.
your rev-dip may be related to gummed up stuff on your air intake valve. just needs carb cleaner to clean it up. i have had that happen a lot on cars because of just gunk build up over time.
just make sure you aren't in a state that will check that each year.
HI doesn’t require it.


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your rev-dip may be related to gummed up stuff on your air intake valve. just needs carb cleaner to clean it up. i have had that happen a lot on cars because of just gunk build up over time.
I don’t see an air intake valve my Corolla’s throttle body.

I already cleaned the original throttle body’s butterfly valve and no change. I then replaced the entire TB thinking the original was defective. No change as well.

I also replaced the electronic accelerator pedal and no change either.

PS. I’m not getting any codes or check engine lights either.


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I don’t see an air intake valve my Corolla’s throttle body.

I already cleaned the original throttle body’s butterfly valve and no change. I then replaced the entire TB thinking the original was defective. No change as well.

I also replaced the electronic accelerator pedal and no change either.

PS. I’m not getting any codes or check engine lights either.


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The butterfly valve is what i was talking about but couldnt correct what i said till now but u got it. As long as it moves freely and doesnt stick in any way.
The butterfly valve is what i was talking about but couldnt correct what i said till now but u got it. As long as it moves freely and doesnt stick in any way.
Yes that one is clean since it’s a remanufactured TB I got in there.

I’m still getting a rev dip going from idle of 700 rpm to 1,200 rpm then back down to 700 rpm when I step on the accelerator 1/4 inch and maintain it. I stall the car sometimes when I start de-clutching thinking I’m still at 1,200 rpm.

My guess is air is restricted by that charcoal filter and MAF is sending signal to the injectors for more gas then cuts it down when more air actually gets through. Or, my oxygen sensors need replacing, or I have a clogged fuel injector.


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Yes that one is clean since it’s a remanufactured TB I got in there.

I’m still getting a rev dip going from idle of 700 rpm to 1,200 rpm then back down to 700 rpm when I step on the accelerator 1/4 inch and maintain it. I stall the car sometimes when I start de-clutching thinking I’m still at 1,200 rpm.

My guess is air is restricted by that charcoal filter and MAF is sending signal to the injectors for more gas then cuts it down when more air actually gets through. Or, my oxygen sensors need replacing, or I have a clogged fuel injector.


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Could be a throttle position sensor that is slightly off and needs calibration?
Could be a throttle position sensor that is slightly off and needs calibration?
Thanks but there TPS is built in to the throttle body and electronic accelerator that I just replaced.

Last resort is to bring to the dealer and have them diagnose it with their scan tool.


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Thanks but there TPS is built in to the throttle body and electronic accelerator that I just replaced.

Last resort is to bring to the dealer and have them diagnose it with their scan tool.


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Im just giving suggestions. I havent messed with the tps on my 2016. If the filter removal doesnt work, we all can hopefully figure it out
Im just giving suggestions. I havent messed with the tps on my 2016. If the filter removal doesnt work, we all can hopefully figure it out
I appreciate it. I’ll post here how the charcoal filter removal goes this weekend.


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I appreciate it. I’ll post here how the charcoal filter removal goes this weekend.


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Mercoron, another thought. on the 2004-2008 corolla, we had rev-dip issues with those cars or the two i had, and i found that replacing the intake manifold gasket totally fixed that one, but i haven't heard of that happening with the 2014 and newer corollas..
Mercoron, another thought. on the 2004-2008 corolla, we had rev-dip issues with those cars or the two i had, and i found that replacing the intake manifold gasket totally fixed that one, but i haven't heard of that happening with the 2014 and newer corollas..
Rich-d, yes I already replaced the intake manifold and throttle body gaskets when I replaced the PCV valve. Didn’t solve the issue.

Another thing I did was clean the MAF sensor with an MAF sensor cleaner and no luck as well.

Spark plugs were replaced a year ago too. Alternator was replaced 6 months ago.

Thanks.


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