S.A.I. Filter Modification, in VVT engines. To prevent its failure! Alert Alert! (1 Viewer)

[2001LC]

We've a $2.00 part in the S.A.I. (secondary air injection) system of the VVT engine, that is taking-out ~$7,000.00 $15,000 $25,000 (inflation) in parts. WOW!

I've a very easy and cheap WORK AROUND. You are going to love this

This thread is dedicated to the 4.7L 2UZ-fe VVT engine, in the 2006 & 2007 100 series Toyota Land Cruiser & Lexus LX470 manufacture in Japan for the USA market.
It also applies to all 4.7L 2UZ-fe VVTi such as in the: GX470, 4Runner, Sequoia, etc. Every 2UZ-fe 4.7L VVT engines, S.A.I. filter will fail. AND then get CAT (Catalytic Converters) DTC (AKA: CEL. AKA: MIL. AKA: codes) P0420 (BK1 CAT) & P0430 (BK2 CAT), and likely both will need replacing. The damage will continue until engine is trashed, if not corrected.

These engine were the first 100 series to have the emission reducing Secondary Air Injection System ( AKA: S.A.I. system or A.I.). I'll just refer to as S.A.I. or A.I..

** Edited 9/7/24 S.A.I. filter, is being suck into impeller of pump. We now have reason to believe: The filter is shrinking and air flow being restricted with age and dust. The more server (heat, cold, humidity) the climate, the faster filter fails.

** Edited 9/14/23: In 2021 or thereabouts. Lexus began a campaign to replace all GX S.A.I filters. The TSB points to moisture as possible cause of filter breaking down. I'm now of the opinion that all Toyota & Lexus will need this S.A.I. replaceable filters ($20) mod, or S.A.I. pump replaced ($600 part) as PM.

After ~5 years reading (in mud) about these codes (P0420 and P0430) coming up with no real cause or legal fix found. I spent the last two years on a 100 series 2UZ-fe VVT engine (my test rig). That I bought with CAT & S.A.I. issues. Just to understand, find, correct and test a fix with. I've decided, it is time to post my findings in mud.

THIS IS NOT WHY all CAT's FAIL. But it is very likely all in the 4.7L VVT engine will fail, because of the S.A.I. filter failing. The modification you'll see here, will save the VVT engine, and it keep street legal. For just pennies on the dollar. So cheap and easy!

I've found what is going to take out our CAT's. Unless this legal modification done. We're faced with, Toyota Dealership fix. Which is near $10K (If both CAT plus S.A.I. DTC (CEL) pop up. Toyota fix, is not a permanent. This filter S.A.I. MOD, is a permanent fix.

The SAI system will kick off DTC (Diagnostic Trouble Codes) P1442, P1445 and or P2441. Which are the SAI switch(s) "stuck closed". These switches typically will test okay, but keep kicking off DTC indicating stuck closed. Toyota has TSB on these. That my Toyota parts guy gave me, when I asked about P1442 & P1445. Which are, Bk1 & BK2 SAI switches, which sit on water bypass joint rear. The TSB, recommends replacing all mechanical parts of SAI system, with a notation * Replace ONLY If damaged by debris. Reuse parts when possible. Which in 2019 was about $3K in parts, just for SAI stuff. Some block-off the S.A.L system, which solves the issue. But, Blocking off S.A.I., is not street legal (Off-road use only). Because block-off kits, increase air pollution, beyond manufacture design. These block-off kits (depending on which kit), are also cause other issues.

The part in the S.A.I. am I talking about.. Is a small foam filter, just inside the secondary air injection blower fan (S.A.I. pump)

Here is a factory SAI filter in good condition, exposed. It resides, under the top of Secondary Air Injection Pump - Toyota (17610-0C010) (Blower) without bracket, list for ~$600 today.

This bit of foam filter material measures, is from a failed SAI filter. It's about 15mm x 5mm. Which is only remnants of a SAI pump filter found remaining in my test engine.

A links to other area info posted in mud on S.A.I DTCs:

P1444/P1445 - Secondary Air Injection System

Is there not enough room to jack up the cab? I. E... Like with lift spacers? Sounds like an extra inch would make all the difference?

forum.ih8mud.com

 

[2001LC]

Drum roll.............the fix... replaceable filter! HA!

Once modification installed, is a $20, 3 second no tool PM. So easy...

Below are pictures, using a borescope to inspect under intake manifold. I'm looking into S.A.I. pumps intake port. Which in this one, we can see:
The filter is intact, which we want to see. So if getting CAT or S.A.I. codes (DTC), look elsewhere (other than filter) for cause.

 

[2001LC]

Why do I think this little filter in the A.I. is taking-out our VVT A.I. system and CAT:

Basically: Unfiltered air, carrying dust with its various contaminants, into engine and on into CATs internal honey comb passages.

This unfiltered air is blowing throughout system, during cold start up, for about 90 seconds.

The purpose of the S.A.I. system is to add oxygen to CAT so that they heat faster when cold. That is all secondary air injection system does. In a nut shell: It suck outside air from under the intake manifold, an delivers it to the CATs.

If filter get clogged, we'll get various S.A.I. codes. Typically stuck closes codes. If filter missing, than in time will get some of same codes (stuck closed) and possible others.

Why would missing filter of the Secondary Air Injection system pump, give us stuck closed DTC(s). The switches of the system become mucked up (dirty) with debris. I suspect the primary failure point, is the pressure sensor on the main switch. I say "suspect". Because I was going to just replace just the pressure switch, last time I had intake manifold off. But decided to just toss in a used main switch with the pressure sensor (Pressure Sensor comes with SW). I was sure enough the switch would take care of the P1442, P1445 and P2445, it did!

How was I "sure enough" it was the pressure switch:
Basically I tested SW by the book (FSM) and some ways not in the book. Along with all the A.I. components. Replace some with known working parts. Nothing tested bad, nor kept the code from coming back up as pending or active (confirmed). System just kept throwing codes. I'd either get P1445 (BK2 sw stuck closed), which seem to come up the most. Or P1442 (BK1 sw stuck closed). Or both, if I went long enough without clearing codes.

The P1445 came up first (found studying history of vehicle) and was before my ownership. That switch which sits on back of water bypass joint rear, on the right side (BK2). PO had Midas replace, which they used a NAPA aftermarket SW. My first attempt after testing (tested OKAY), was to install used known working OEM SW BK2. Made no difference. I also swapped out the VSV switch connect to it and vacuum line used to attach them, with used known working OEM sw and new vacuum line. I preformed all test, before and after. All test OKAY! But codes kept coming back.

The only difference I could see by simply looking into the main switch and my used switch. Was color variation. My old switch had grayish dirty appearance inside, the used (on my shelf) looked silver and clean inside. Used replacement main switch did the trick. No DTC in over 40 cold starts at time of writing this, since install. Which was ~10 months after I removed internal AI pump filter (remnants of) and replaced with my external replaceable filter with mod.

Likely it's just microscopic debris in pressure switch or it's feed tube. FSM has us test pressure Switch at ECU. Which tested okay. Had I, just replaced the pressure sensor only. Than I'd know for sure, it was sensor. But if wrong, I'd than have to pull intake manifold again. So I just toss in the whole main switch (used OEM know working), which had pressure senor on it.

Main switch (old factory installed from test VVT engine). Pressure sw attached to top with 2 bolts and vacuum hose connected it to switch body.

Inside switch has a grayish tint, most notable on round shaft inside (rod). Other used switches I have, where filter was still intact. Rod is shinny silver and inside has a cleaner appearance.

 

[2001LC]

Parts needed to make hose assemble, for routing from S.A.I. pump air inlet, out from under intake manifold. Which I then attach replaceable filter to!

I consider making air filter routing hose assembly, out of carbon fiber. Which would be cool, and could be made to fit perfect. This was to be my first prototype, as a model. But this works so very well, and all components easy to obtain locally. So I'm just sticking with this assemble for now .

The power grip is a heat shrink clamp. Inside the hoses is a 1" barded coupler. The coupler(s) come with barbed ends and a smooth shaft/pipe jointing the barbed ends. I cut these down, so that one end barded and other end smooth. By simply cutting off one end. The barb end is inside the 1" heater hose. The smooth end of one, is in Toyota elbow hose. Then the heat shrink clamp seal and clamps the hose onto coupler in the two hoses. The other bard coupler has smooth end protruding out end of hose, for attaching filter onto. The heat shrink clamp is a safety, making sure hose will not pulled off elbow.

The screw clamp holding 1' hose onto the A.I. pump, is not really needed. That hose is very very tight on the A.I. pump without it. But as a safety, I used it.

Here you see before either clamp installed. The hose is a supper tight fit onto A.I. pumps top 1" OD inlet port. So it is very important to place elbow on pump at correct angle (orientation), as it's near impossible to rotate once on.

Note the slight kink (smash-down) narrowing bend in the elbow hose. This elbow hose, is a very tight fit, as is just a tad too large. So I very carefully kinked where I wanted kink to be, to make the most relaxed fit. I looked inside to make sure kink would not obstruct air flow, it did not.Works well tight, as it can not bounce around.

I cut the hose to fit at 6 7/8" after I attached assembly to pumps top. So that the air filter would fit sung between throttle body and water bypass joint goose neck. I did not want the hose or filter vibrating or bouncing around. Which could damaged hose assembly, filter, throttle body plastic cover or wires in area. It works very well, sit nice and sung from end to end.

With just one hand, I can grab filter and remove it.

Hose assembly fits very nice between Intake manifold (once installed), head and water bypass joint front.

The filter is a UNI 1" (motorcycle filter). It is easily replaceable. It's is a compressed foam filter, molded to rubber ends. The rubber works very well, reducing vibration, and aided in sung fit. Even if I does get some minor vibration or bounce, it's not going to damage throttle body plastic. Manufacture claim good for 2 to 3 years, depending on use.

I considered using clamp to secure filter to hose assemble, but no need to.

Changing A.I. filter, at same time as engine air filter, would make PM scheduling a piece of cake.

It did take me a week or so, to come up with parts to make this easy and cheap. I'm happy with it. It's been on my 07 for about 11 months now. I removed intake manifold after 10 months. all look good, no heat damage or any vibration damage.

During the 10 months I did play with restricting air flow. By placing a reducer between filter and hose assembly. Did not seem to make any difference, so I took it back out and run it unrestricted.

As for removing the intake manifold. For me that's is easy. It a starter job more or less.

I do replace all intake gaskets as I always do any removed. Since I disconnect throttle body and leave it resting in place. I replace its gasket as well
2) 17171-50030 GASKET, INTAKE MANIFOLD TO HEAD, May 05- (06-07 VVT)
1) 22271-50050 GASKET, THROTTLE BODY May 05-

The very most important part of this job is cleaning top of engine first thing. The area between heads and intake manifold hold sand, dust and grim. We do not want even 1 grain of sand, getting into intake ports, getting on valve seats or dropping into cylinders. That is a compression killer and can lead to engine that looses power, smokes and damages CATs.

My final step before installing intake manifold. Is the get up on the engine with a flash light and shop vacuum. With small hose on vacuum. I vacuum every single particle out form the intake ports.

Sometimes, I'll find the bracket to hang wire housing block to water pipe, busted. Most times. I do the tear down day 1. Then call local Toyota Dealerships for parts.
82711-1E320 white bracket clips into water pipe.
Or
Some wire housing block, securing clip busted. So I replace those housing block.
90980-11149 2 wire housing block main SW.
90980-10845 Pressure sensor 3 wire, wire housing block.

I don't have the P/N, for wire housing block that hangs on water pipe to pump.

 

[2001LC]

Almost a year after installing this S.A.I filter mod, on my test vehicle. I was still getting some S.A.I DTC. I suspected the pressure sensor attached to main SW, had become compromised with dust in the very tiny orifice. I tested the pressure sensor at ECM (CPU) as prescribed by FSM) spec 1v to 2.2volt). It test okay at 1.19Volt!
[ Edit May 2023:. No S.A.I DTC after replacing main SW with it's air pressure sensor. No CAT DTC since adding replaceable SAI filter mod. With the exception of 1 CAT DTC pending (Ran scanner, every-time I drove for nearly 2 years to pick up pending DTCs). Which was due to about 100 short drives in 3 moths (less than one mile), on cold engine start up. Without ever getting up to full operating temp or driving at HWY speeds (RPM). ]

So I pulled the intake manifold again. With intent of replacing the pressure senor. Once I got in there I decided to go ahead and replace main SW, sensor attaches to. Upon inspection of main switch, I note graying inside on it's main valve. IMHO, was a confirmation of dust blow through the system, due to it's failed filler. I elected to just go ahead and replace main SW with a good used I had on hand. Why? Didn't want to pull intake manifold again in near term. I felt I could have gotten away with just the pressure senor swap.
Gray on shaft of main SW indicates contaminates getting into system

 

[97 AZ LC]

We're looking forward to this with bated breath and baited breath.

 

[cybrstar]

I don’t get it? What do we do?

 

[Njck22]

Curious to see more on this. I want this to be the problem. I would assume however, the foam would be pyrolyzed to ash quickly in the cats.

 

[jtb517]

Curious to see more on this. I want this to be the problem. I would assume however, the foam would be pyrolyzed to ash quickly in the cats.

I don’t think it’s the foam filter itself that causes the issue, but the lack of the filter. Over time it’s letting unfiltered air, dust, debris into the system.

 

[Njck22]

I don’t think it’s the foam filter itself that causes the issue, but the lack of the filter. Over time it’s letting unfiltered air, dust, debris into the system.

Right you are. brain decided to check out early today(or several years ago). I suppose toyota made this decision to avoid having to redesign an airbox/airbox lid for just one market. I think the 5th gen 4Runners SAIS tees into the airbox.

 

[J1000]

More likely what is killing cats is exhaust leaks, "tick tick." Leaks let fresh air into the exhaust > O2 sensor reads lean > computer injects more fuel which turns to soot and clogs the cats. Replaced several cats on Cruisers this year and every single one had pre-cat exhaust leaks.

 

[2001LC]

I'll first repeat. This AI pump filter is not only reason for early death of a CAT.
Excessive heat, raw fuel or just to rich a mixture for to long, coolant, air leaks into exhaust pre or in-between CATs, impact to CAT, flood waters depositing contaminates, prolonged and excessive idling causing build up in CAT due to run below optimum temp, etc. They can all individually or in combination, damage a CAT.

But why, in seemly good running VVT engine without any of the usual upstream cause. Are both the VVT 4.7L CATs going bad (in only some, to date). Then replaced CAT's , they go bad again! There must be a reason why P0430 & P0420 at same time more or less, in VVT 4.7L. More so than non VVT 4.7L. Much more often, considered in terms of percentage of them on the road, compared to non VVT. It was once suggested, possible the EUC set to sensitive, perhaps that's part of issue, IDK.

I do think filters foam, is just the start of CAT damage (clogging). The fan blades plastic, in this test case, added to clogging I suspect. But only the start of clogging CATs!
DUST blowing in over time, IMHO becomes the final nail in the coffin. The straw that broke the camel's back, as the saying goes.

Anyone that has done a starter job, knows how much dust builds up in the engine valley. Even in a daily driver, that never sees dirt roads or trails. Imagine a rig following others on the trail. How much dust builds up under intake manifold, where the AI is sucking air from. Albeit only ~90 seconds on cold start up, it adds up.

I tried to clean CAT of BK1 (OEM factory) & Bk2 (Davico CAT installed by PO) in my test case. I used 44K, Seafoam fogger, Chevron techron, Cataclean with many Italian burns (high RPM runs to cook off gunk from the CATs). Did not help. Note: Side benefit of this. When I pulled intake manifold. The intake ports of heads were cleanest I'd ever seen, near new looking.

I even pulled A/F sensor of BK1 only, and sprayed Seafoam directly on factory CAT face, while engine running. Made a little mistake, in leaving Seafoam straw in A/F port, while I crawled out from under vehicle, to turn key off (kill engine). That few seconds without fluid of Seafoam running through straw, melted straw. Subsequently I ran my snake camera into port and found clump of hard melted plastic on face of CAT. Even after Italian burn at 5K RPM for 10 minutes more that 1/2 dozen times, clump of melted plastic straw remained at side of CAT face.

I also scoped the CAT material (two in each VVT CAT), from between them thought 02 port and from the rear. The face of CAT looked clogged, with some improvement after Seafoam. The backside of forward CAT along with face and backside of aft CAT looked clear, very clean without appearance of clog.

So sure seems a clog issues. But does this also damage CAT, by coating internally reducing effectiveness. IDK, but certainly possible.

After melting plastic straw accidentally in AF port, a clump appeared at bottom of CAT BK1 face. Even after doing more Italian burns (high RPM HWY runs of ~7 to 10 minutes repeatedly, to cook CATs).

Back side, which appears very clean without any signs of clogging..

 

[2001LC]

I don’t get it? What do we do?

I add a very easily replaceable SAI filter.
Which Toyota factory SAI filter is difficult to get and NOT PM item, nor is it sold separately by Toyota.

Curious to see more on this. I want this to be the problem. I would assume however, the foam would be pyrolyzed to ash quickly in the cats.

I've some evidence (pictures above). Plastic may indeed, be a contributor.

I don’t think it’s the foam filter itself that causes the issue, but the lack of the filter. Over time it’s letting unfiltered air, dust, debris into the system.

I totally agree.

Right you are. brain decided to check out early today(or several years ago). I suppose toyota made this decision to avoid having to redesign an airbox/airbox lid for just one market. I think the 5th gen 4Runners SAIS tees into the airbox.

I continued to look for others, that had or have AI & CAT codes in the 4.7L VVT. I have found some others, and filter was confirmed gone. I hope this thread will flush out more that find the same. We'll need detail on DTC history, overall condition of engine and exhaust. Key is with these A.I. & CAT DTC. Is or was A.I. filter gone.

The 4.7L VVT was the only one I know of, where AI is under intake manifold. The idea to modify AI filtration, to have external filter is not new. I saw guys doing this on other Toyota SAI pumps. Those system are a piece of cake to modify and PM. They just stick filter on end of S.A.I pumps (blower) intake port, after removing internal filter cover.

Our 4.7L VVT just takes more work to get at S.A.I. pump (blower) and pipe to where it becomes a very easy PM to replace filter.

More likely what is killing cats is exhaust leaks, "tick tick." Leaks let fresh air into the exhaust > O2 sensor reads lean > computer injects more fuel which turns to soot and clogs the cats. Replaced several cats on Cruisers this year and every single one had pre-cat exhaust leaks.

For sure, air leaks is cause for CAT failure. Which Toyota has in diagnostic tree when we get CAT DTC to be checked. Which I've known many 100 series with exhaust leak, which 98-02 was very common years for. My 01 had it (crack) on both exhaust header banks.

But interestingly. On all those I've seen or fixed exhaust manifold leak. Not one had a DTC P0430 or P0420 in history or current. I know one now, that's ticking all the time from cracked exhaust manifold. Which if still ticking after warm up, means very bad crack/O2 leak. It has been for over 100K miles. CAT has yet to throw a code.

So I find it very interesting you: "Replaced several cats on Cruisers this year and every single one had pre-cat exhaust leaks" Interesting in knowing; yr and mileage of each and how long/miles leak active after warm up before CAT went bad?

_________________________________________________



It is always mechanics best practice if not duty, to find cause and correct. When dealing CAT(s) it is very important, or DTC for them tend to return.

This thread is specific to the VVT. We've threads started years ago in mud. That are specific to VVT P0430 & P0420 both coming up. They'd fix all usually upstream suspect and install a new CATs, only to have P0430 & P0420 return. So I'd been wanting one to work on.

I finally got one (07) with all the issue, I call me test rig. Early on A light went off in my head, after reading an ad on ebay for: Rebuilt Toyota S.I.A pump. Guy stated in description. "Don't worry, I'm a Toyota Master mechanic. I replace the filter which is the failure point".

AI Filter failing, could it be affecting CAT. Could filter and dust be blowing in on CATs on cold start-ups, clogging them. certainly possible. I pulled my A.I which is pictured above.

I did the mod and continued to look for others, that have/had the same DTCs and found filter gone. I found some.

My hope this thread will flush out more that find the same.

 

[04UZJ100]

How about just bypass the system altogether?

 

[jerryb]

I just don't get or believe how trash can travel through the rear coolant void, make it through the 2- 2.5 mm or so opening of the air valve (with an offset bore on the pipe tube) down the air tube, into the log, into the exhaust chamber, out the chamber and into the exhaust manifold log and down to the front face of the first cat.
It must survive the highest temp anywhere on the car.
It must travel against pretty serious back pressure pulses.
It must be light enough to make it through the rear coolant bypass air void. Anything heavy is going to fall out of the stream, the back pressure pulses make it even harder I would assume.
I don't know. Seems unlikely to me but who am I.
Still, if it's so easy for crap to make that path and destroy cats then I'd weld that s*** shut pronto.

it is the first year, and second that they started using wideband sensors. There should have been some, or some drastic change in the rear narrow o2 sensor reporting and outputs of the ecu. I bet there isn't. The rears are very sensitive.

Every enthusiast deals with this same problems on most all car makes. In toyota fashion they're just really late, but they did learn a bit from the germans from the late 90s. 1996 if you like.

 

[2001LC]

How about just bypass the system altogether?

That is one solution. But only legal with off road use. To use on any public road in the USA is a violation for altering vehicle pollution systems.

I just don't get or believe how trash can travel through the rear coolant void, make it through the 2- 2.5 mm or so opening of the air valve (with an offset bore on the pipe tube) down the air tube, into the log, into the exhaust chamber, out the chamber and into the exhaust manifold log and down to the front face of the first cat.
It must survive the highest temp anywhere on the car.
It must travel against pretty serious back pressure pulses.
It must be light enough to make it through the rear coolant bypass air void. Anything heavy is going to fall out of the stream, the back pressure pulses make it even harder I would assume.
I don't know. Seems unlikely to me but who am I.
Still, if it's so easy for crap to make that path and destroy cats then I'd weld that s*** shut pronto.

it is the first year, and second that they started using wideband sensors. There should have been some, or some drastic change in the rear narrow o2 sensor reporting and outputs of the ecu. I bet there isn't. The rears are very sensitive.

Every enthusiast deals with this same problems on most all car makes. In toyota fashion they're just really late, but they did learn a bit from the germans from the late 90s. 1996 if you like.

Isn't that the same as saying air can't get to CAT from AI Pump, or Toyota had no need to even put filter in A.I. pump.

Again. Block off or welding shut is not street legal.

 

[jerryb]

No I'm pointing out that solids have a long road to make it to the cat. Of course air can get there.
Of course there ought to be a filter, I'm not saying you're wrong.
It's just a very convoluted path. Debris has to survive exhaust chamber temps, travel though the voids and valve lifts and stay entrenched in the air stream.
Then, the whole point of it is that it clogs the cat enough to decrease efficiency. I don't think they're that much related.

 

[2001LC]

Jerry you've good points, in that heavy debris will have difficulty making the journey. Heavy particles IMHO, will not even get sucked into port of air pump for that matter. Certainly there is question is to what composition, how much and to what effect would make and would it take to clog or damage a CAT.

But certainly fine dust will make the journey. We've the air intake filter, so dust does not get in from vacuum. Without air intake filter, we'll damage valve guides (super tight tolerance), valve seats, rings, cylinder wall. I'm not and engineer or scientist. But I'll bet air pushed by A.L pump, is moving faster at a greater pressure, than that of the vacuum of intake. So may even carry more dust, and likely even heavier and large size practicals.

Denver itself sits in a basin. We get what's called the brown cloud. It is considered pollution and is. But it is also dust. Dust cloud that was here before the cars or even the city. As City grew, the cloud became even worse with brake dust, tire dust, etc. So we've lots of different practice of various materials in dust. Fortunately pollution laws, have materials used in brake and tires, resticked for the better. I'm a strong believe in population laws, and not circumventing them. But what all is in dust, takes a scientist to answer. Then engineer to say what may or may not be damaging to our CATs.

Also consider the naked eye can only see down to about 30 microns. We actually see even smaller practicals, or seems we can, as sun shine through slit of partially open curtain in a dark room. We're actually seeing the sun reflect off dust particles, smaller the 30 microns. Even rian or snow is dust, moisture attaches to until heavy enough to fall from the sky. So can we at least agree, dust is everywhere and can certainly travel the distance to CATs IMHO, and a lot of under right condition.


Sticking to CAT face and internal channel:

Yes, A.I. filter was obviously put in place to filter out dust from the air entering the system. So how much dust and of what composition can a CAT handle and what would make dust stick more so than other times is key.

Seems sticking in CAT, would be more of issue in rigs that idle excessively and/or run at low speed (RPM) on trails or roads. This condition of low RPM does build up gunk, that despots on CATs internally. Giving dust more to stick too.

As far as what composition of contaimines in dust, that is most detrimental to CAT. Or how much is too much contaimets in a CAT, before they're damaged to point we get a DTC. That would take someone well above my pay grade to answer. Which perhaps, as this thread devoples and explore the possibility. Will get more answers.

@jerryb, it was for this test rig. I wanted (want) those sweet CATs you've hanging on your wall. I'm still interested in them Even if just to borrow, but more than willing to buy them..

I could be wrong here about the CAT being damaged, from unfilter air blow directly on them. This thread may help answer that. May even prove me wrong about the CATs, perhaps! That's fine!

But the air of the AI pump needs filtration at minimum, or the AI system fails. The TSB Toyota has out on our AI system. IMHO is from unfilter air. That TSB requires all components be replaced. Pricy!

Anyone can block it off AI system, which makes the 100 series illegal to drive on public streets, roads & HWY in the USA. There are thread on block-offs kits in mud, and all over the web. Will they be discovered by the EPA (Emission test station), not likely. But I don't need a COP standing over me, to obey the laws.

This thread is about about keeping the 100 series VVT street legal in the USA, and as stock as possible while meeting all legal environmental requirements. Also keeping the engine health.

I'm not first to add a filter. Just first to give a solution on the VVT 4.7L, that I know of.

Some history on test vehicle driven in the Rockies:

It actually came from GA and spend some time North Eastern seaboard, likely second home or office of POs father. (eye Doctor)

Infact this test rig had BK2 CAT replaced by Mid-ASS (Midas muffler in (Glenwood springs CO) about a year after coming to CO. After father gave the son, and son moved here.

The shop also replace BK2 A.I switch with a NAPA SW, the BK2 CAT with a Davico. It was the worst R&R job, I've ever seen. Every single point this Mid-ASS tech touch, he screwed up 5 different air leaks, could not have been worst. The vehicle history shows, first had codes read at a shop In grand Junction. Which is first town on I-70 coming East from UT, on the way to Glenwood Springs CO. PO got these A.I and CAT codes after roaming the UT desert and canyons one of his last trip in this rig.
This thread has some of what I found on BK2. I also found Midas R&R BK2 A.I SW with NPAP. Later I found the tech also needlessly pulled BK2 SW to exhaust header tube. It also had stirpped studs and air leaks.

https://forum.ih8mud.com/threads/rt-help-ive-new-exhaust-nuts-stuck-any-ideas.1170382/.

Why does this matter, where this VVT 4.7L was driven and what done to it:

Well I get rigs coming to me for service, that are built and spend time in UT off road and/or southern CO. The light red color dust and mud these rigs have on them, is nasty stuff and sticks. If fact Merlot (07LC built & heavy, one of my all time faroter rigs) was in from the East coast for service (T-belt and whatever) with me this past summer. It had been in UT among other off road trails from coast to coast, since last in my shop about 40K miles earlier. It is a very clean and well maintained rig, with only 100K now. I'd been power washing the engine bay, undercarriage, suspension and radiator fins for about 2 hours. I could see it just wasn't cleaning film off well. My main concern was the radiator fins. So knowing @abuck99 does exception good cleaning’s to his stuff, after running off road trials. I called him. He recommended a soaps mixture I've now adopted. After letting soap mixture soak in radiator, I power washed again. The amount of red dust that now come off, was truly amazing. But still, on parts radiator fins and suspension, I could easily see the film. The film was not washing off as well as I’d like even after soaking. Really, it takes actually scrubbing with a soapy brush to get clean. How much still remained in the fins after first power wash without soap, and how much still remains hard to say. Sticky S*t!

I see this, often, around here. Some say the S**t is radioactive mud & dust and will never come off.

So now consider the test rig was driving around the CO mountains and UT canons, with no filter in the AI system for some time. Each morning he'd fire it up, it suck more and more dust from under the intake. Which the blower, blows in more air (with dust) on relatively cool CATs to bring temp up faster, that its job. With rich startup mixture of cold engine blowing into CAT's also. I'd think the rich mixture would also make dust stick even more.

Fast forward a year about after I purchase:

So after a year or so of testing this engine and working over systems. I came up with a theory as to what took out the CATs, as it did take them both out. Theory relied on finding a A.I. filter gone or disintegrating.

So at the being of 2021, I finally pulled the intake manifold and A.I pump. Sure enough I found the A.I filter gone! Or just the tiny bit, remaining, as seen in OP first picture.

I do have some question as to what happened and how to filter was damged?? Which I'll get into later.

But there's no question. A.I. filter is very much needed in street legal VVT 4.7L.

 

[2001LC]

Why/how are these A.I. pump filters damaged.

Well IDK for sure:

Possible;

• Rodents!
• Age!
• What environment used in!
• Factory foam composition defect!

Filter loss may not be happening to all. I say"may not". Because in my test case, I did have rodent damage. History at Lexus.com shows in 2012 at 67K miles (~7 yrs & ~90K miles, before CAT codes reported). A Lexus Dealership repaired rodent damage to VVT cam sensor wire and both knock sensors replaced. Knock sensor damage is sure sign rodent were under the intake manifold, where A.I. pump and it filter are located.

But it is possible these filter may all degrade, falling apart on their own over time. I say this, because of what first made me even consider the A.I. filter a central player in issues. Was ebay ad for rebuilt A.I (Secondary Air Injection Smog Pump), and a TSB from Toyota.

Ebay seller claimed to a be a Toyota Master mechanic. He stated he: rebuilt A.I. pump by replaced the filter, it was the failure point he claimed. I was looking at this ebay sellers statement: in the light of a TSB my Toyota Parts guy handed me,. After I asked what parts are, associate with A.I. codes P1442 & P1445 I was getting. In the TSB, it states as note to parts list: "Replace only If damaged by debris. Reuse parts when possible" What debris and where from, I'm thinking. Then I saw ebay ad

BTW: I did and I am still looking at all A.I. parts from my system for debris. Which I've not found any big enough to see with naked eye. What I do see is internal parts look gray & stained. Whereas other used A.I. parts (different 4.7L VVT) i have, internally look clean & shiny in comparison where filter was still in place.

Looking into the into statement debris and filter of A.I. pump. I found other Toyota forums (non Land Cruiser), adding aftermarket filter to A.I. pump. Why were they mitigating: Likely failure of filter/clogging and subsequent damage to A.I. system. Resulting in very costly system repairs bills. They said, adding this aftermarket and changing filter on regular basis, was the key to health of A.I. system. In those system, A.I. pump is not under the intake manifold and is easy to just add the filter. Google, and you'll find them.

In considering the TSB (debris) note in A.I. parts, filter being central to A.I. failure in other forums dealing with A.I pumps, and no other reasonable cause found in my test rig for CAT going bad. Also considering how much others had made sure all systems okay as I did, but yet new OEM or aftermarket CAT installed just going bad again.

I then came up with a theory: CATs are being taken out by loss of air filtration of air blown directly on them, during cold start ups for 90 seconds from A.I. system.

This (debris) too, is likely why Toyota TBS and why I kept getting stuck closed DTC pointing to BK1 & BK2 SWs. I thought: Could it be debris is being blown directly from A.I. pump, causing A.I. systems failures and the CATs. No one to my knowledge had ever said this or done anything with this filter in working to solve repeated CAT failures. Until I did, about 1 year ago now. When I pulled my intake manifold. Sure enough my test rig A.I. filter was gone! Which it had to be for my theory, to stand.

For the last year after installing my modified A.I. filter. I let A.I. codes keep coming up. I worked through the system one component at a time again and again. I came to conclusion it was main SW, not BK1 or BK2 SWs that DTC pointed to. That likely main SW had debris in it. More specifically, the pressure sensor connected to it. I replaced main A.I. SW and no more A.I. DTC for the first time.

Over the last year I kept looking for others with both P0420 & P0430 that also has A.I codes and filter from A.I. Pump was also gone. I found one doing a PPI for a local. It had it all, but No mention of rodents. A.I. system blocked off and aftermarket CATs was it's cure. Not legal, but interesting block off A.I. and CAT DTC did not come back. BTW: it was an 100 series. Also a note: When looking at the ih8mud Hewitt block off thread, we see very little about CAT codes or then returning.

Chew marks:
These may be chew marks on impeller blades. But chewed-up or busted fins extend further than 4 fins opening exposes for rodent.

I found remnants of rodents in engine valley. Likely old from 2012, just not cleaned out. See chew marks on wire protective wrap housing, next to air intake tube. A full size mouse would likely have difficult time if not impossible, to squeeze into ~3/4" ID air intake tube of pump. But certainly a baby mouse could squeeze in. So it could be I've a rare case here of rodent eating the filter perhaps, perhaps not, IDK.

In addition to chew marks, I found old nest under the A.I. pump and main Switch.

 

[2001LC]

Number one rule before replacing CAT(s). Find and fix cause, or DTC will likely come back and CAT goes bad again in most cases.

First think, have I been prolonged idling. Yes! Get fuel system cleaner in gas tank: i.e Cataclean, 2x cans 44K or 2xcans chevron techron pre tank (all or any one, but just one type at a time). Do "high RPM burn outs" on HWY (Italian burn), clear codes and see if they return.

Make sure engine well turn, running at proper temperature, and no exhaust leaks and fuel trim within range (-+5%) also check CAT for impact and tail pipe for clues of obstruction.

Those with VVT that gets either or both (especially if both) DTC P0430 & P0420. Likely also get A.I. DTC, but may not. Do all above also. But before replacing CAT: Should inspecting A.I. pump filer. IMHO.