Okay so after a while of not starting a 4.0 V6, that I’m looking to pass down to my sister once she gets her license, when I start it up every now and then it sound like a knock? Or a dry chain? Lol there’s oil in the truck but it doesn’t sound good but the noise gradually goes away. And drives normal. Does have p0420 codes and plan on changing the cats soon after a year or two of avoiding it. Also can a knock sensor cause this? I thought the knock sensor code would be coming bc of the bad cats. Can anyone relate to this?

Strange.

So... T4R03 ... How many miles on your 2004 4runner?
I'm wondering how "loud" your knock is?
Drives normal???? You are lucky.... so far!

This is what the internet says about your CODE PO420.

What does code P0420 mean and what do you need to do?
What Does P0420 Mean ? The function of the catalytic converter is to break down harmful pollutants that are created by your vehicle during the combustion cycle and convert them into less harmful gases. Code P0420 indicates that the catalytic converter is not functioning efficiently, therefore increasing the output of harmful pollutants by the vehicle.


I have a 2005 V6 4.0 L, 4runner with 150,000 miles. I'm in Nassau Bahamas where it's short trips all day.

NEVER threw a code in 15 years of ownership!

Starts up like it did in 2005 when I bought it off the dealer's lot. Runs the same too. Doesn't burn any oil. Never a misfire.

What else could you want?

Oh! No rust anywhere on the body. Underneath on the frame - just superficial rust. Original tranny shifts fine. Fluid changed at dealer (6 quarts) with regular Toyota ATM (not the synthetic) at 105,000 miles. Says 6 quarts on the dealer's receipt, but I question the amount.

Had a 1996 GMC Jimmy that rusted away to a pile of rust junk in 10 years. That ended ever owning a GM product ever again.

Replaced three starters along the way on the runner. I keep a back up from Amazon for $99 in the garage. OEM WP, Alternator. The first big job is the evaporator core needs replacing now. A $92 part at Amazon. My mechanic wants $300 labor.

If it's a quick chain rattle sound that goes away after a second or so then the oil filter's ADBV is not working or maybe the filter doesn't have one.
Throw a new OEM Toyota filter on and see if that doesn't fix it.

If we're talking a prolonged rattle then I'd start looking at oil pressure.

I suspect its something like this too. I saw on some other Toyota group this was happening to someone else. I'd change the filter and oil. Then run it for a few miles, and change both oil and filter again just to make sure any contaminates aren't floating around or clogging up the new filter. Toyota filters are PN 90915-YZZD3

Not a single sentence here related to OPs question.

I change the oil every 3,000 and have always replaced with OEM filter. Although it leaks a tad bit of oil at the pan the dipstick reads full. The first occurrence I had with this issue the dipstick read empty until I started it up again and let it run a bit. And thanks for pointing out about that other guy. The same thing ran through my head after I read his post.

Could be carbon build up blocking passages or in the vvti valves. I periodically add MMO Marvel Mystery Oil to the oil 1Qt in the oil every 3rd oil change. Works well.

Thats good that you keep up with the changes. The other case I was referencing was actual an OEM Toyota Filter purchased at a physical dealer IIRC, let me see if I can find it. In my option, they're one of the better filter options and I use them myself. It sucks, but things happen, and it might have a bad anti-drainback valve. The tell tale is removing the filter, and if it doesn't spill a filter full of oil out, the anti-drainback valve within the filter is bad.

Looks like the post is from Facebook and not sharable, but I can PM you where to find it if you want to read the comments and stuff

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exactly! this guy seems to feel the need to post crap about his 4runner or unrelated comments that dont pertain to the topic or question asked... nobody cares if your 4runner doesnt have any rust.

I think he picked a very appropriate username...."Captsolo".... seems to be in his own little world, I can't recall any of his posts that offered any helpful advice or solutions, they all have been solely about his T4R and almost always off topic.

If it is at start-up and goes away after warm-up, Id rule out it being a bad knock sensor. You would likely have a check engine light with a knock sensor related code and you would also likely be able to detect knocking or detonation-related events, particularly under acceleration. As a corollarly, this would likely not manifest at start-up where the DME fuel trims are rich, but would mainly occur under acceleration where the knock sensor would interrupt the DME, so your scenario does not fit the knock sensor.

This also rules out bad fuel, IMO.

Sounds like a timing chain tensioner or an oil pump. A variable valve timing solenoid fault can also cause noise, but a check engine light would generally also show up and my supposition is that you would have an intermittent issue with a miss . . . Im not very familiar with the Toyota variable valve timing system so I might have to research it a bit before I put it on this.

It could also be nothing, but a youtube video could help.

This is interesting . . . so far I have gone with Toyota filters and they seem pretty good. I might have to look into a remote oil filter solution as the miles climb on the 1GR-FE.

I have been using the Toyota filters myself also and have been satisfied. At $4-$5 a filter, they're certainly a great value. Unfortunately I think crap just happens that caused that one to have an ADBV failure. This is the only OEM Toyota filter failure I've heard of.