Knock sensor advise needed

[AceEngineer]

I've got an '02 EP3 with 148k on the counter, bone stock. I'm getting a P0325 code for the knock sensor. The FSM has a wiring diagnostic procedure culminating in replacing the sensor. The replacement instructions simply says that the intake manifold bracket must be removed. My problem is getting the sensor and connector in sight or even the bracket for that matter. I don't want to remove the intake manifold if I can avoid it, no gaskets have been cracked on the engine yet. Is it possible to reach it from the bottom, or by removing the alternator, or moving the radiator? The FSM doesn't say what you should remove to gain access. Surely somebody has faced this before and can tell me the easiest way to get at the knock sensor. :confused:

Thanks in advance,
AceEngineer

[USAF EP3]

You are going to need a 1 1/8" wrench and/or socket to get on that sensor. Sadly, the easiest and least intrusive way to get to it is by removing the intake manifold. You don't need to remove it completely, if you manage to loosen all the bolts and create a gap to fit a wrench parallel to the block you can loosen the sensor and reach with your arm and hand underneath the hanging manifold to loosen the sensor the rest of the way.

I've done 3 of these this way and each of them didn't take longer than 2 hours from start to finish.

[LouisianaEP3]

I have this code as well and just bought the sensor. Will replacing the sensor fix this code?

[Ba82Ep3]

The knock sensor can be a bitch to get out. Pulling the intake manifold is the EASIEST way to do it. Pulling the radiator is the MESSIEST way to do it, and still doesnt give much room to work in. The intake manifold bracket is useless. Toss it once you get it off.

Even with the intake manifold off, removing the knock sensor can be tricky, considering the space to do so. I would also take the opportunity to swap your thermostat. Its inexpensive and much easier to get to it as this time.

[AceEngineer]

USAF EP3,

Does removing the intake manifold break any water passages?

AceEngineer

[Ba82Ep3]

No water passages are opened.

[USAF EP3]

USAF EP3,

Does removing the intake manifold break any water passages?

AceEngineer



No water passages are opened.


Actually, he mentioned his car was bone stock and untouched for the most part. The water lines that route to the IACV on the throttle body will have to be disconnected to get underneath the manifold with your hand.

[Ba82Ep3]

Ah! Good catch Kev. I dont think ive had those for over 5 years now lol

[AceEngineer]

I appreciate all the good advise, thanks to all!
I lowered an endoscope into the area under the manifold yesterday and studied the area. The brace is nowhere near the knock sensor and it looks like there is space to get an arm up from the bottom and unplug the sensor. Don't know whether I can get a stubby wrench on it. The new knock sensor takes a 27mm wrench. I'm going to try this approach first. If this fails, this is what I am going to try next: I'm going to unfasten the throttle body from the intake manifold, remove the two studs and then leave it in place as I remove the intake manifold. This will not require me to break the cooling loop, and all I will need are two new gaskets, the throttle body to manifold and manifold to head.
I'll let you know how it turns out.

AceEngineer

[AceEngineer]

Well guys, here's how it turned out.

I got her up on stands and crawled under her the other day. I could get my hand on the Knock Sensor, unplug it and probably could have changed it that way with a cutoff wrench, although I would have scraped the crap out of my arm. I decided that pulling the intake manifold was the better way to go for several reasons. All the connectors that the KS signal go thru are also up under the manifold and the diagnosis process in the FSM accesses the signal thru them. I wanted to double check the wiring and plus changing the KS was then easy. I did not have to break into the cooling system. I unbolted the throttle body and was able to pull it back far enough to clear its studs with the cooling lines connected. I unplugged the fuel line and left the fuel rail on the manifold. I removed the two studs along the top of the manifold then the rest of the bolts plus the bottom bolt on the brace. The intake manifold with brace attached then came right out straight up giving me great access to the pertinent connectors for the wiring diagnosis and the KS. The wiring all checked out OK. A new KS and two new gaskets and she went right back together. I held the metal manifold gasket in place with some tweezers while I started the two outside bolts and then put the studs in last. I spread the work out over two days because I have to do it outside in my drive and it has been in the upper nineties here the last week. I erected a big camping rainfly over the car for shade, but still could only work in short shifts before returning to air conditioned space. Getting old is a bitch. Maybe a total of five hours spent doing the KS. I also removed the bumper and installed some eBay fog/driving lights in her while she was up on the stands which took another slug of time. The fog light wiring is a whole other story I plan to write a DIY in the near future about what I learned.

AceEngineer

[Karma]

I know this is somewhat old, but I wanted to touch on this knock sensor issue because I just replaced mine this past week.

I found it easier to go from the bottom, but that may be because I have short skinny arms. I did the actual hand work from underneath while a friend guided me from the top. He helped direct which way to point, turn, and rotate the socket for removal, then for the sensor install. The sensor isn't torqued down that tight, so once it broke loose, it was all hand turning. It really was much easier than we thought. The reach up and in isn't that far. You may not be able to grip the actual sensor with your fingers, but once you get the socket on you're good to go. It was also helpful to place the sensor in the socket when reaching up to install, instead of trying to twist it on by hand.

I know most people say it's best to go from the top, but don't hesitate to try from the bottom, especially with 2 people. It took us maybe an hour at most to do the job. Best part is no loosening or removing the intake manifold, or anything else up top. I did scrape my arm a little, but nothing serious.