Morning all — this just started after some recent maintenance.
My 2006 with 302K miles was getting terrible mileage (~6.1 MPG) and felt lethargic. P0420 popped up, so I replaced the O2 sensors, spark plugs (OEM), and Denso coils — all torqued to spec (plus a hair on the plugs).
The next morning on a cold start, I heard the Secondary Air Injection Pump run, shut off, then a few seconds later came a deep, two-beat rumble — like a distant Jake brake or a modern V8 switching to sport mode — lasting about 2 seconds. It happens randomly, but always only on the first start of the day.
I've ran back through my checklist, and vacuum hoses are good, and everything plugged in. This doesn't sound like the SAI Pump, however I guess it could be?
What says?
You may have multiple issue going on.
The sound could be SAI pump (blower). They'll make a sound, as they shut down/turn off. Typically, if we hear it. The filter within it, is gone. The sound is usually ~90 second after cold start up. SAI pump, does not cycle on and off, after warm up. They just turn off.
Another sound we hear, is fan clutch. We get a turbo sound on cold start. About 90 second as clutch release from fully engaged, reducing spin (turbo sound) on fan. Others sounds are; bearings of tension & idler of fan belt and timing belt, also alternator. If HVAC on Auto, AC compressor is another.
S.A.I. TSB out years ago. Call for, replacement of pump and the 3 switches. when certain DTC pop up. What happens is; the filter within S.A.I pump, shrinks and is suck into imperller. It's foam rubber and the dust it has collected. Is ground up and pushed through the S.A.I. system. All the way, Into combustion cylinders and on into CATs. With no filter, it continue pushing/blowing dust on every cold start ups. On the GX recall, for S.A.I. filter. Toyota sighted, the filter may be affected by moisture. I now have very strong evidence, it is. S.A.I. filter are affected by moisture and server climates. The higher the humidity, the sooner they fail. You don't even need to drive/start the engine much. I recently found a 25k mile 07LC, with bad filter. In fact, all foam rubber was bad. Form end to end, meaning engine compartment, speakers, etc. The S.A.I. foam filter, lasts the longest, in mild, dry climates. But all will fail.
I've seen, three different OEM S.A.I. pumps. The difference, is the filter. But no matter which pump (filter, the filter will fail. It a dump design, to have a non replaceable filter. Most if not all Toyotas, after 2005 have, S.A.I.. There's is a very simple answer to this issue. Easily replaceable filter.
IMHO the block-off-kits, are not the answer. In fact, those kits, that tap into MAF. Are causing issues. They'll also not street legal.
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...
The S.A.I. has nothing to do with MPG. Except two possible I can think of:
1) Switch stuck open. Which will/should produce a DTC (CEL). Would dump extra o2 into cylinders. This should result in limp mode, if not; MPG may be affected.
2) Dust dumping into cylinders, will result in lower compression.
YES! I'm not the only one! 2006 lx with 215k now and I've heard this less than a handful of times but can't seem to track down. Jake Brake is the perfect way to describe it. Lasted only a few seconds. For some additional data... my SAI was OEM replaced at Lexus 12 years ago at 88k. I'm considering the block plates or even the serviceable filter mod but holding off until I have a real reason to take the intake manifold off.
SERVICE: OTHERS
DESCRIPTION: ~|~CUSTOMER STATES CHECK ENGINE LIGHT ON VSC & TRAC LIGHTS ON ~|~P1445 SECONDARY AIR INJECTION VALVE STUCK CLOSED CAUSED BY DEBRIS FROM AIR INJECTION PUMP BLOCKING AIR SWITCHING VALVES ~|~REPLACED AIR PUMP ASSY AND THREE AIR SWITCHING VALVES ONE TIME GOODWILL FOR PARTS ONLY-GUEST TO PAY LABOR PER DSPM AUTH# R0916C
Typical of high humidity climates. TBS require all SAI replacement, nice parts under wrty at 127K miles.
I use my directional bore scope with 6mm camera, to inspect these filters:
As long as filter still in view, you can wait.
If to dirty or brown (old dirt foam) kept very close eye on.
If gone, either replace S.A.I. pump or do my replace filter mod. You can do a block off used OFF-Road only (Trailed to off road). But avoid those that wire in, especially if to MAF.
Filter of S.A.I pump (blower), gone from view. In this 25K mile 07LC, out of Gulf coast LA area:
Cap removed.
On the bright side that’s 300k+ solid miles before it went out, pretty impressive to me. I have the Hewitt SAI bypass kit installed around 4 years ago and haven’t had any P0420 related issues since. It basically bypasses the SAI motor and alters the signal to run natural aspiration during startups especially when it’s cold. First time I experienced it was 4 winters back and it stayed on limp mode, no unusual blower sound. After the install engine operated normal again.
So nothing else done?
S.A.I. SW Stuck open DTC. Is the one, that place vehicle in limp mode. It a safety, so we don't continuously add o2 to cylindres (lean fuel mixture). Which, if due to filter being gone. Also means, continuous dust introduced.
Did you ever do a compression test? Numbers?
