I have a 1999 chevy malibu with knocking noise ina 3.1l v6 motor.

there are lines that go to your transmission to the side of the radiator maybe one of the are bad

intake air sensor? there is a air sensor on the air cleaner box, there is a mass airflow sensor on the rubber hose to the throttle body, there is a idle air control on the throttle body that looks like a little black motor,

I just replaced this on 02 xterra 3.3 L V6. The knock sensor is in the center of the engine block below the lower intake manifold. Its a lot of work but it wasnt too hard just took time. Getting some of the hoses off in rear of motor was hardest part. But you need to remove upper and lower intake manifold and you will see it.

First, I would like to mention that most knock sensor codes are not caused by the knock sensors, but a mechanical problem with the engine. The knock sensors cannot differentiate between noises caused by mechanical problems like a bad pulley bearing, bad motor mount, noisy alternator bearings, etc. and spark knock. knock sensor codes are set when the computer has retarded the timing as far as possible to compensate for ignition ping (Spark Knock) and the noise still exists.

With that said, here are the instructions.

Remove the Intake Chamber assembly.
Disconnect Injector connectors.
Disconnect the heater hose from the Intake Manifold.
Remove the 9 bolts. 2 nuts, 2 plate washers and Intake Manifold assembly.
Remove right hand engine mounting stay and water outlet.
Disconnect the following hoses and connectors:
Radiator inlet hose.
Engine coolant reservoir hose.
Engine Coolant Temperature Sensor connector.
Engine Coolant Temperature Switch connector.
Ground strap connector.

Remove the 3 bolts and right hand mounting stay.
Remove the wire band.
Disconnect the water bypass hose from the inlet housing.
Remove the 2 bolts, 2 nuts, 2 plate washers and water outlet.
Remove the 2 gaskets.
Disconnect the Knock Sensor connectors.
Remove the Knock Sensors.

Broken stabalizer links, broken stabilizer bar, and worn out stabilizer bar bushings are fairly common. As well as the rear bushings on the front lower control arms. A quick inspection of the front end and you should be able to tell if the links are bad, bar is broken, or the lower control arm bushings are separated. If the rear bushings on the front lower control arms are seperated the lower control arm will look like it is resting on the subframe.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

(step 1 ) the torque specs for the heads are---1998 through 2001 are 37 foot lbs. ( step 2) rotate an additional 90-degrees (1/4 turn). intake manifold bolts ( lower ) step 1-- 62 in-lbs, step 2--115 in-lbs. intake manifold bolts/studs ( upper ) 18 ft-lbs. this is for the 3.1 v-6, have a good day!

Under the intake manifold in the valley of the motor, upper and lower intakes have to be removed to gain acess

Is it noisy with only the blower fan on or does the A/C have to be on to get the noise.
Try using the heater only and see if the noise is present.
Let me know.
Regards,

you have to remove the whole distributor

i have toyota windom 4vz-fe i need locate knock sensor