HCF Delete good or bad idea?

Ive seen only a touch of info on the idea of removing the hydrocarbon filter (HCF).
Wondering what the experience has been from the crew on here who’s performed this mod?

also, there is a thin sheer/mat of what appears to be polyester loosely laying on my air-filter as delivered.
Is this also a factory item?
What is said purpose?

 

That’s the hydrocarbon filter. You can search for the removal method and the anecdotal results in this and the other forum.

I read an article somewhere that someone actually dyno tested before and after removal on a different vehicle and there was a slight benefit. And track testing 0-60 MPH resulted in a fraction of a second improvement. But it was so slight that the drivers did not notice any improvement in the butt-dyno category.

 

You're not going to gain anything from removing it.

 

Pictures?

what are you talking about?

I noticed the original air filter from Japan had a thin layer that looked like a white scotch bright pad.

New air filter from dealership did not have the pad. Part numbers are different too.

 

Looked like a prefilter…OEM replacement filters are super thin compared to that OEM factory filter. Factory filter has very deep pleats. I tried asking for the factory filter and parts guy said they cant order it.

Also, what and where is the HCF?

 

That’s a pre-filter bonded to the paper filter. It comes OEM, intended to be a universal filter around the world where there’s a lot of sand/grit. US local dealers stock a version without the pre-filter (17801-YZZ13) but you can get the other version (17801-38051) at some online dealers.

But sometimes they actually deliver the 17801-YZZ13, saying the other one is obsolete or discontinued. Make sure their return policy won’t cost you anything to return it if they send you the wrong one.

Here’s a post on TW for removing the HCF, the 4 Runner is similar.
https://www.tacomaworld.com/threads/diy-secondary-air-filter-removal.2012/

 

I remember seeing another thread on this subject. I think you can find the Japan factory filter online. But US dealerships carry the filter without the pre filter.

I replaced the original filter last year. The replacement looks exactly the same as far as pleats and thickness, it just didn’t have the pre filter (scotch right) pad.

 

Thanks all for chiming in
@ElectroBoy thank you kindly for the link and clarity on the OEM filter backstory. I figured it was some sort of pre-filter, wondered if it was only from factory or ongoing with filter changes. Im racing towards an air filter change and starting to determine what to use. Considering the AEM dry filter- more research pending…

as for the HCF delete it is definitely limited in info and void of any meaningful or corroborated data. On the surface it seems like it would be an air flow restriction to me and removing it would have not downside for the vehicle. As for an environmental impact i suppose there’s a downside there.

Wondering… (at the risk of if igniting the age old firestorm…) Lets try not to get off into the weeds on this next question.. a yes or no suffices- plenty of thread on the rest of topic already——
—— wondering, does the TRD CAI system have an HCF?