SO upcoming work, timing belt, vc gaskets, fuel injectors. 290k on clock. Less than 3k ago did a compression test , leak down test and cooling system test and all is good.
My last 4runner had a knock sensor crap out at 160k. Did both and harness.
With all the above work im going to be doing, its not many more bolts to then get to knock sensors, and compared to a ton of work, if that was the only thing a person had to do.
Sure nobody likes spending money for no reason, but.... they will be so near.

thoughts ?

If you're already doing the work I don't see why not, and you can get the plenum+manifold gaskets as a set which helps if you choose to, but there is truth and beauty in the phrases "if it ain't broke don't fix it"/"don't mess with what isn't messin with you." With that said though, I had a gremlin in my knock sensors/harness a while back that initially started with one of them going dead, and I'm at similar mileage as you (It happened around 285k iirc.) If you know they haven't been done I'm leaning towards shoot for it
Also make sure to use the Denso sensors instead of Matsu

Since your doing injectors I guess it would be wise, personally I'd probably skip injectors, intake manifold and knock sensors until the ECU flagged one them as an issue, I realize the new style injectors can be tricky but the rest should be fairly straight forward to diagnose/narrow down. You can revisit that group of components at anytime fairly easily.

When I replaced my engine, I had it down to the intake manifold and decided not to do the sensors because of cost. Within a year on my "new" engine, the knock sensors failed.

I agree with the thought you are already there so it's a good idea.

I’d at least replace the harness for them if you’re pulling the intake. Disturbing the harness while doing the injectors and timing belt is possible.

My knock sensor connectors literally fell apart removing the connectors from the sensors they were that brittle from age and heat.


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agree, that harness can be real brittle. The last time I did the knock sensors, my harness also just crumbled in my hands. Made me wonder if I really had a bad knock sensor or just a burned out harness. But when I was that deep I was not gonna 2nd guess, and just replaced it all.

Armyama has them for 98 each but does not specify if Denso or other, just genuine toyota. Of course fleabay has "Denso" ones for like 30 each...doubt they are real denso.

If i recall the Matsushita ones are around that price and Denso ran a bit more, but they also look quite different if a picture if provided. Pictures of either one can be found on google to cross reference

I wouldn't replace them due to the cost. Once you know how to do the work, getting back in to the intake manifold really isn't that hard. You won't need to remove the valve covers again but you will need to get the throttle body, plenums and fuel rails out of the way.

Now, if this was an engine swap like we did recently and you have to swap over the intake manifold over to a rebuilt engine, that's when I would go ahead and replace both knock sensors and the harness because the intake manifold is already off. You already dropped decent coin on the rebuilt engine so why not spend some more on new knock sensors and harness.

well its just a thought and I appreciate the feedback and ideas. Maybe I will pass at this time. As you said, its not that hard to get into there, and I have had throttle bodies etc off a few times b4 and have done vc gaskets on these twice b4. So I guess just getting to knock sensors would not be that hard at a later date. Could use the money other places/mods

And really you can leave the TB attached to the upper plenum, so we are talking two extra plenum gaskets which I argue can be reused if a lil (super thin layer) ultra grey is used between bolts, although frowned upon.., and again all these items are usually fairly easy to diagnose if problematic now that we know the new style injectors like to throw a misfire and flashing CEL. Then at that point I'd splurge for knock sensors, wire harness, all intake gaskets, temps sensors, injectors and orings, and be done with it.

My only concern nowadays is will these parts be available OEM in the future, I have good inventory for this truck on the shelf but not everything, so do you buy it now while cheaper/available incase you need it is the other question.. My 92 Eclipse has become almost impossible to get parts for unless I go for EVO 1-2-3 parts which are also rare.., although there is good aftermarket support, we all know how that can go.

I just dropped about $500 ordering new knock sensors, the harness, and the intake and plenum gaskets from McGeorge. Popped a P0325 on the recent below zero days which I'm sure is just the harness letting go since it comes back instantly, but one of those "while I'm in there" type of things.

I did my knock sensors 3 times last year because I was trying to cut corners and save some money last year. I should have done what you are doing and it would have saved me time and money. Lower intake manifold gaskets aren't cheap and I had to trash a set or two.

Also, every engine I've worked on has had the Matsushita sensors, not DENSO's. I wonder if it is a part that was superseded?

That's my biggest issue, I wouldn't want to just do the harness and have to go back in there on the slight chance it was the sensor. I'm curious to see if it's the Densos that show up.

three years ago I did knock sensors, cause I had too...throwing codes. I got the knock sensors from McGeorge.Im pretty sure what they sent were Denso. Cant be positive on that.
Someplace Ive read that the denso were better than the Matsu..... brand, dont remeber where I read that.
Aryanana has the best price for "genuine toyota part" but does not specigfy brand. From Aryana, the two are the price of one at McGeorge.

That's what it set me back, plus a pair of OTR.