Knock Sensor Failure Likelihood 3.4L with 70,000 miles.

I went through this when I bought my Taco with knock sensor codes @ 223k miles. Replacing them isn't hard but just a bit labor intensive. But I also ended up changing spark plugs, wires, valve cover gaskets and manifold gaskets while I was in there.

The knock sensors themselves are pretty stout. They are easy to test with a multimeter but a pain to get to. If you pull out the sensor, you can hook up the positive lead from your multimeter the to the back of the sensor and ground the negative lead. Then tap the sensor gently against something. You should see voltage.

You can check for continuity with your multimeter via the knock sensor wiring harness and that seems to be the real cause of the KS codes. They are sitting right in the valley above the block, beneath the manifold and are constantly subjected to high temps. Over time the wiring becomes brittle and will break. That's exactly what happened in my case. But I opted to go ahead and replace both knock sensors with the harness due to my mileage and since I was already in there. Brought it out of limp mode and woke up the car. It's not something I'd like to do again!

 

Also here are a couple of photos for reference I was able to dig up from when I did mine to give you an idea of how buried they are in there.

 

On the same page. Already ordered the hoses. I'm 2WD. Ordered a new RMS. Need to order the Trans Seal.

Do I need to drop the trans or can it stay in place while I pull the engine?

 

Thanks for sharing the pictures.

Did you remove the LIM with the injector rail attached? The reason I'm asking as I would like to install the new injectors and rail to the LIM and put it under a fuel pressure test outside of the engine. One of my cars delivers 60 psi of fuel pressure. I like to run a fuel line from it to a new rail project to test for leaks before I start installing it.

 

I removed the lower intake manifold first and then worked on removing the fuel rail. You need the clearance to be able to access the fuel rail.

 

Good deal.

 

I’m in that boat now, just powdercoated my valve covers and checking valve clearances while I’m in there, bought a KS harness too. Gawd I hope 1 of my LIM bolt threads in the head ain’ stripped. 276k debating on being cheap and not buying the KS.. no codes though.

 

The knock sensors look to be very well built. The best that I've seen. If you are not getting any codes, your sensors are good. Actually, when I bought the truck earlier this month, it had a knock sensor code. I reset it on the way home and it never returned. I suspect a problem with the wiring harness. Since I'm replacing that engine, the sensors and harness will not be used.

Unless someone removed your LIM in the past and cross threaded a bolt, it will be fine.

Do show us a picture of your powder coated valve covers. I'm toying with the idea here. I think power coated valve covers will be easier to keep clean.

 

do you have a pic of what VC looks like after the powdercoat?

 

i am still wondering why one part of my VC started a small leak recently yet the back side no leak and not sure when if ever they might start a leak
i try to run a pretty tight ship on my engine

 

This reminds me, I need to replace the 21-year-old fuel pressure regulator while I'm in there.

 

how vital is that?
for preventive purposes

 

How old are your gaskets?

 

when's the last time you flushed out your brake fluid I need to check mine to see if it could use a good flush

they were originals at 113k, until recently

 

You just replaced them and they are leaking?

 

Bengal Red, It’ll be nice to not look at 20 year old roached vc’s, lol.

 

Nice, Dam now I wish I had painted mine when I had the supercharger off 4 months ago.
ANOTHER thing to do now,
Dam this site, it just never stops

 

My friend hooked me up he was doing a sand rail and threw these in for $50, for both..

 

i am headed to open the hood now and visualize this lol

not yet but I gonna check on them, just concerned about the cams