2006 LX470 knock sensors Question

[Thatonedude]

Hi all,

I believe something got to my knock sensor wiring...

Do they sell just the wiring harnesses or one that is universal from another vehicle?

I have a 2006 LX 470 with 154k miles and wanted to get some opinions on what to replace, etc.

The shop (Lexus Dealer) said it was a 6 hour job and would be around $1200 give or take.

Thinking of having my Boeing mechanic friend help since it doesn't involve doors, Etc.

I know the intake needs to come off so what all should I replace while I'm there?

Knock sensors = yes
Knock sensor wiring = yes
Intake gasket = yes
Starter = yes

Anyone recently tackled this job or something similar and have any part numbers handy?

Is it worth me taking on or is this a job you pay for? Not sure of the difficulty!

Thanks in advance!

Yes.... this is their left over dinner on my engine... mac and cheese...

 

[suprarx7nut]

Thinking of having my Boeing mechanic friend help since it doesn't involve doors, Etc.

I re-did the knock sensor wiring on my old Supra. The trick was that it's shielded wire so that needs to be properly handled. Not quite just a wire replacement. I'd assume the 100 is still the same arrangement with shielded wire.

That dealer quote seems small actually. I'd expect them to replace the entire engine harness which probably retails for $1500+ itself, not counting any of the labor or other consumables needed.

If your mechanic friend is familiar with electrical then it should be a breeze for them, but I'd count on more than 6 hours.

I don't think there's any kind of universal harness, nor do they separate the knock sensor from the main engine harness. That's typically a part of the entire engine harness and there's no segmented point where you can simply replace the harness. It's one continuous shielded wire from sensor to ECU.... at least that's what I bet it is.

 

[SteveH]

Before you or anyone pulls the intake, you must carefully power-wash the engine, focusing on the intake-to-block junction on both sides. Then, when you pull the manifold, you must be super careful to watch for debris (plastic wiring harness clips, etc.) that tend to fall into the valley or the cylinder intake areas (where the valves live) while you have the manifold out.

I ran my shop vac many times and still found things that fell into the intake ports. You (or your mechanic) truly cannot be too careful on this job. You are careless at your peril. Frankly, I don't trust most shops to do this job, so I did it myself. The very LAST step before lowering the manifold is to recheck all the intake ports for debris.

In my case, one of my knock sensors just died, so I replaced both @ $156 each, along with the starter (dealer Denso). My harness was fine (although I had a mouse nest among it).

 

[LJE]

I re-did the knock sensor wiring on my old Supra. The trick was that it's shielded wire so that needs to be properly handled. Not quite just a wire replacement. I'd assume the 100 is still the same arrangement with shielded wire.

That dealer quote seems small actually. I'd expect them to replace the entire engine harness which probably retails for $1500+ itself, not counting any of the labor or other consumables needed.

If your mechanic friend is familiar with electrical then it should be a breeze for them, but I'd count on more than 6 hours.

I don't think there's any kind of universal harness, nor do they separate the knock sensor from the main engine harness. That's typically a part of the entire engine harness and there's no segmented point where you can simply replace the harness. It's one continuous shielded wire from sensor to ECU.... at least that's what I bet it is.

One correction - at least on my 2005 LX, the knock sensor wiring starts as part of the starter harness, not the main ECU harness. There's then a connector right on the back of the driver side of engine where it plugs into the main ECU harness.

@Thatonedude FWIW, I've got a pair of new knock sensors that came off of a tech school block from a Sequoia/Tundra (never started/run/etc) that I'd give you a decent deal on. Again, brand new OEM other than the fact they've been sitting installed in a dormant engine for 20 years.
Come to think of it, I've actually got that starter/knock sensor harness as well from that tech school engine - I'll have to look if it uses the same connector at the back of the engine as the LX does. If that's the case, I'd be willing to sell you the knock sensor part of that harness as well if you'd be interested. Shoot me a PM if you'd like!

 

[Thatonedude]

Hey guys! Sorry for the delay. Got sick with Covid and busy with work.

My buddy was here last weekend and we knocked (pun intended) everything out! (Even with sickness)

A big whew!!! No Doors falling off...

I air blew the engine and then steam washed it and air blew it again. Cleaned up nicely.

We managed to get everything off with only a few broken clips ha! And let us tell you, the bottom right starter bolt was the hardest part wtf!!?

It was indeed a chewed wire; knock sensor wasn't even connected!

Picked some denso knock sensors up 2 for $20ish on eBay (shipped from japan); cheap! But they work as they should! New/refurb denso start was $189... also picked up two Toyota wires and two knock sensor clips as well as the intake gaskets.

First start was a little rough, not sure if I was to prime anything but after it warmed up, it ran smooth...

Which brings me to my main issue now... cold starts... gives me rough idle.. and sputtery acceleration (not bad but can tell it's not smooth) but once the motors warmed up, it idles and accelerates just fine... I'm thinking maybe MAF sensor is dirty given I was spraying degreaser when the air box was open... I am running some bg44k to clean up the fuel system since I had it all open...

One thing to note is, I am still getting P0453 code... had it before... and just found the cause... rats chewed the canister wires at the back of the truck... I hate them... but this code was present before the knock sensor fix (i just didn't notice the actual wires chewed) and glad I don't have to spend $500 on a new canister!!

I heard/read about possible throttle body recalibration... I wouldn't think it's the fuel injectors but can't rule that out...

Possible causes:

-Dirty MAF
-Throttle Body recalibration
-Ignition/coil packs
-EVAP canister wires chewed in back given P0453 (again was present before i replaced the knock sensors, and there was zero idle issues, just sluggish (still smooth) slow acceleration)
-Fuel Injectors

but thought I'd ask while I'm digging through threads!

Thanks guys!

Rats:

 

[Thatonedude]

Also, my god! Throttle response is back!!! I hit the gas and it responds instantly!!! No more feeling sluggish!!!

And my (full tank) fill-ups instead of showing 190miles to E now show 250 miles to E!

 

[Thatonedude]

P0302 code: misfire cylinder #2.

Bought a new coil pack. Will install and test today to see if it resolves issue.

 

[Thatonedude]

Well... changed the coil pack and issue with rough idle still present... sat there for a moment and rechecked firing order.... f me... changed 7 instead of 2 lol! Left the new one in 7 and placed the old one in 2 and bam! Engine running buttery smooth again!

Now onto rewiring evap canister for P0453 code...


Note: double check firing order lol