knock sensor bad?

[anrivera]

recently, my message center started showing "service engine soon" so i took it to 3 different auto parts stores to check the code for the message.  All 3 said it was a problem with the knock sensor.  One problem! I dont know where the knock sensor is.  Can anyone tell me so I can check if its loose or broken?  Its a 2002 z71 5.3L.

[Left in Disgust]

I think it's around the rear of the intake manifold...

[ShapeShifter]

They are conveniently located under the intake manifold.  

See attached file for the removal instructions. Look out for that first step! Removing the intake manifold is a four page procedure.

-- SS

[Dae Ma]

Wow, Under the intake..that sucks with all the stuff (hoses, wires, clamps...yada, yada),  they just couldn't place them on the exterior of the engine.

[FSHNGUY]

I'll bet hey put them there to run up the cost of the repair, and give the mechanics a chance to scratch the paint on your fenders when doing the repair!!

[NYCBlueZ71]

I need to do this too. Anyone have an idea how many hours the labor will be? Also, how do i get a mechanical guide like you have ShapeShifter?

[sperry]

P0332.. Bummer.

Knock Sensor (KS) System Description

Purpose

The knock sensor (KS) system enables the powertrain control module (PCM) to control the ignition timing advance for the best possible performance while protecting the engine from potentially damaging levels of detonation. The sensors in the KS system are used by the PCM as microphones to listen for abnormal engine noise that may indicate pre-ignition/detonation.

Sensor Description

There are 2 types of KS currently being used:

    * The broadband single wire sensor
    * The flat response 2-wire sensor

Both sensors use piezo-electric crystal technology to produce and send signals to the PCM. The amplitude and frequency of this signal will vary constantly depending on the vibration level within the engine. Flat response and broadband KS signals are processed differently by the PCM. The major differences are outlined below:

    * All broadband sensors use a single wire circuit. Some types of controllers will output a bias voltage on the KS signal wire. The bias voltage creates a voltage drop the PCM monitors and uses to help diagnose KS faults. The KS noise signal rides along this bias voltage, and due to the constantly fluctuating frequency and amplitude of the signal, will always be outside the bias voltage parameters. Another way to use the KS signals is for the PCM to learn the average normal noise output from the KS. The PCM uses this noise channel, and KS signal that rides along the noise channel, in much the same way as the bias voltage type does. Both systems will constantly monitor the KS system for a signal that is not present or falls within the noise channel.

    * The flat response KS uses a 2-wire circuit. The KS signal rides within a noise channel which is learned and output by the PCM. This noise channel is based upon the normal noise input from the KS and is known as background noise. As engine speed and load change, the noise channel upper and lower parameters will change to accommodate the KS signal, keeping the signal within the channel. If there is knock, the signal will range outside the noise channel and the PCM will reduce spark advance until the knock is reduced. These sensors are monitored in much the same way as the broadband sensors, except that an abnormal signal will stay outside of the noise channel or will not be present.

KS diagnostics can be calibrated to detect faults with the KS diagnostic inside the PCM, the KS wiring, the sensor output, or constant knocking from an outside influence such as a loose or damaged component. In order to determine which cylinders are knocking, the PCM uses KS signal information when the cylinders are near top dead center (TDC) of the firing stroke.

[ItsStopher]

I need to do this too. Anyone have an idea how many hours the labor will be? Also, how do i get a mechanical guide like you have ShapeShifter?

I had a DTC P0332(bank 2). this was the day after going through a HUGE puddle. Last week I took off the intake and pulled both sensors. The front sensor (bank 1) had a little rust on it, so I cleaned it up and put some dielectric grease on it and reinstalled it. The rear (bank 2) was REALLY rusted, the sensor was covered in water. I used a shopvac to get the water out and then I cleaned up the sensor used some more dielectric grease on it. The rubber covers did not fit so I used some rubber tape once around the cover to make it a tighter fit. Then I reinstalled every thing and started it up. The DTC has not come back yet. I am still going to replace the sensors, dealer wants $57, advanced wants $39, at www.gmdirectparts.com (PN 10456603)I ordered 2 with shipping it was just over $66.

ItsStopher

[sperry]

Fun, wasn't it!

Here's the 1500 KS R&R instructions.