Detailed review of the Knock Sensor: Removal and Installation

Posted by vlaar, Feb 29, 2004
Articles: Engine & Fuel -

  1. vlaar

    vlaar Proven Member

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    , Gainesville_FL
    What a day! We finished the knock sensor after only 5 hrs of removing items, torqing, and retorqing again:) We made a few trips around town for some tools so this time is included. Here is a detailed review of how the removal and install went from beginning to end. The tools that were used in this install/removal were the following: ratchet wrench w/extensions, 10mm, 12mm, 14mm bolts, and the very important 15/16 wrench. The best size wrench (lengthwise) to use should be no longer than 8 inches. A longer wrench will not fit or give you any sort of leverage because of the odd angle/fitment over the knock sensor. The wrench used was a 12 pt close ended wrench with an open-ended box wrench side. You'll see later that it is VERY important to use the close ended 12pt side as this will prevent any sort of stripping of the knock sensor bolt.

    Here is exactly what to remove (in order) in order to gain "easy" access to the knock sensor itself. Remove the battery (10mm/12mm bolts), battery tie down assembly (10mm), and battery tray. There are four 14 mm bolts holding down the battery tray. You can see two of them from the top on the passenger side of the vehicle. The other two are a little harder. We went at it from around and under the battery tray on the drivers side--still standing on the passenger side. You can go at it from underneath the car, but we opted not to do it this way. Once the battery tray is completely removed, remove the two 14mm bolts on the EGR valve assembly. The EGR is connected to the intake manifold right below the throttle body assembly. This will allow you to see the knock sensor from the passenger side of the vehicle. Now would be a good time to remove all of the unnecessary EGR vacuum lines if you haven't done so already. Now, remove the starter. NOTE: The transmission bolts and the bolts holding the starter in place are EXACTLY the same so make sure to remove the starter ones. A good way to tell which one is which is the tranny bolt (14mm) is that it has two ground straps on it. The starter bolt is right next to it. A Haynes/Chilton Manual has a great photo of where the two starter bolts are if you get stuck. Remove these two bolts and slowly lower the starter until it rests nicely on the lower crossmember of the car. We left it there the entire time during the removal/install. Next, slide the knock sensor bracket off the intake manifold bracket and then disconnect the sensor. The bracket is located near the top of the intake manifold bracket (backside of the manifold). We had to bend the little slide bracket on the manifold in order to get the knock sensor wire off. Tip: put the sensor (NOT the one coming from the knock sensor itself) in a place where it's visible so you DON'T forget to hook it back up!!!

    Ok, here is one of the MOST important steps in this removal process. Spray PB BLASTER (nothing else:) all over the knock sensor. Tip: spray right above the knock sensor so that it seeps down into and on the knock sensor threads loosening them. Let it sit for about 10 minutes or so. Now, take the 15/16 wrench (12pt closed part) and slip this over the knock sensor wire going to the sensor itself. The wire will act as a guide so that you don't drop the wrench into the engine bay. Slide the wrench all the way under the intake manifold until it rests nicely on the knock sensor. To loosen it, pull up on the wrench (counterclockwise) until the sensor bolt loosens. It took me a few tries of really pulling on the wrench in order to break loose the knock sensor. Tip wear a thick glove to get a better grip and to prevent the wrench from digging into your left hand. After the knock sensor is loose enough, remove it with your fingers. Take the brand new knock sensor and finger tighten it initally. Watch the wire as it will turn and want to break/twist off the knock sensor itself. After finger tightening it as much as possible, take the 15/16 wrench and slide it over the new knock sensor wire. I only tightened the knock sensor with the wrench 1/4-1/2 of a turn as too many people have overtightened it and caused more knock to appear. Snap the knock sensor wire back in. Install the starter, EGR assembly, battery tray, and battery in that exact order. The two VERY IMPORTANT things needed for the removal of the knock sensor were the 15/16 stubby box wrench and the PB BLASTER. Without these two things, the job would have been next to impossible to do. We tried many times to break the knock sensor loose before the PB BLASTER and it did not work period! And no, PB BLASTER is NOT the same as Liquid Wrench. Blaster works MUCH better. Finally, the entire reason for me getting a new knock sensor was because I was getting phantom knock with only partial throttle (around 20% according to the logger). I could also feel the black goo seeping from out of the back of the knock sensor beforehand. Good luck with the removal and installation of your knock sensor!
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