ToyoTaco 06

William - Your logic to an engineering type makes a lot of sense. I noticed your location and have a question about the secondary filter.
Anyone - We drive the Taco very hard (off-off road, extremely dusty conditions) for our job (land surveyor on the Western Slope) and have installed a K&N primary air filter (the stock filter didn't do much). When we clean the filter (more often than recommended given the very harsh conditions), we have noticed a need to vaccuum off the secondary filter. It's catching a lot of dust. Have you heard of replacing it? It would seem that the charcoal activation would be gone due to the clogging dust.

vital22re

iTrader: (2)

that k&n filter is worse for filtering than your factory filter. If you're experiencing lots lof dust/dirt. You're better off replacing with stock system.

William

Thanks for that. I'm not an engineer, but I am an ICE (Instrumentation/Controls/Electrician) Journeyman. And my understanding of industrial instrumentation (much of which measures airflow) also means that I have a pretty decent understanding of airflow.

I've only lived in New Mexico for 1 year and 4 months, and I haven't used a K&N here. But I have used K&Ns in Florida, where I lived most of my life.

It's not quite as dusty in Florida as it is here, but I have still noticed a fine coating of dust after the K&N. So yes, dust is getting through.

One thing I've concluded is that with a K&N being an oiled filter, a small amount of that oil will coat the inside of the intake after the filter. And this coat of oil will catch dust, making it more noticible.

So does this mean there's more dust getting through? Or is it just more noticeable because of the oil coating?

My best guess is that it's a bit of both.

I have held a K&N to where I could look through it and saw many small holes. Although the oil will keep some dust from getting through the holes, it won't stop all of it.

One thing I noticed, is that when I replaced the K&N that came with my Tacoma with a Purolater, that the Purolater filter pleats were deeper, and there were a few more pleats. So although the Purolater may have a more restrictive filter media, it also obviously had more filter surface area, and having more surface area could very well mean that it has as much flow capacity as a K&N.

And like I said before, I noticed absolutely no change in power or fuel economy after replacing the K&N with a Purolater and after removing the secondary filter.

Anyway, since it sounds like the secondary filter has already been dirtied by dust and possibly oil too, I'd just remove it. And I would go to a standard filter. It may cost more in the long run, but I think it's worth the cost.

ToyoTaco 06

Thanks much for the info! Great!
Given the dust problem, does anyone have an opinion to effeciency / filtering to an after market air box? Is the cone shaped filter any better? It just seems like a longer intake run to the engine which takes up space in the engine compartment.

William

You are very welcome.

I personally don't have any experience with an aftermarket airbox, what is often called a CAI (cold air intake). The thing about them is that they are often called a cold air intake (as if that gives an advantage over stock), yet the factory setup in every modern vehicle is a cold air intake because it draws in air from the outside and not the warmer engine compartment.

Anyway, some claim gains using an aftermarket CAI. But like with any setup, unless whatever is being replaced is the most restrictive part, it's highly unlikely there will be any gains. And any gains are likely to be with the throttle at or near wide open, because with the throttle at less than wide open, the throttle plate gives the most restriction.

One possible advantage is that an afermarket CAI may have a filter with more surface area, allowing it to have more dust collection capability, meaning fewer cleanings needed.

Anyway, I personally wouldn't spend the money for an aftermarket CAI. The cost is a bit high, and the ratio of cost to gain (IF ANY) is way high.

That being said, IF I were to decide to spend my money on an aftermarket CAI (notice that I said IF), I'd go with one from Toyota TRD. The reason why is that it's designed by Toyota engineers, and they know the vehicle better than any aftermarket engineers.

But even then, I still don't think it's worth the money.

wonder

If anything it reduces the performance of the engine, drilled mine out of my GX470 drove 200 miles, no problems have occurred yet. Gave my engine more power without it! My best guess it was designed to eliminate orders from the intake.