nizmolee

iTrader: (1)

Does any one know what causes this problem.. I noticed it with my truck too. I have a 98 maxima GLE auto with about 50 k on it. It seems there is something internal is loose that may needs adjustment.. any help..

Daniel B. Martin

You should never hear knocking. If you do, something is wrong. It may be caused by a problem with the Knock Sensor which is not severe enough to set DTC 0303 and turn on the Malfunction Indicator Light. It may be caused by an engine sound which is sufficiently similar to the engine knocking to fool the ear.

Engine knock (also called "pinging") is a common symptom of using fuel with a low Anti-Knock Index. It may also be a symptom of engine problems such as a sticking Exhaust Gas Recirculation valve or a lean fuel mixture.


Here is some information about testing the Knock Sensor, taken from the '99 Maxima factory service manual. This test is done with the engine off.

1) Raise the hood. View the engine from the driver's fender. Look into the deep valley between the cylinder banks and below the intake manifold. Identify the KS as a black item fastened to the block by a single vertical bolt. A wire harness wrapped in black leads toward you, out of the valley. That is the KS sub-harness.

2) Follow the KS sub-harness to it's nearest connector. This is connector F121. It is located near the upper right-hand corner of the valve cover of the forward cylinder bank, as viewed from the front of the car.

3) Disconnect F121. You have to do a "press the latch and wiggle and pull" to disconnect it. F121 has only two pins; if you see more than two pins, you have the wrong connector. Use a digital ohmmeter capable of measuring more than 10 Megohms. You want to measure the pins of F121, not the sockets of the matching connector. Measure the resistance between a good ground (such as the battery negative terminal) and pin #2 of connector F121. On my car this is the highest of the two pins, the one closest to the front of the car. The factory spec is 500 - 620 Kohms.