chris j vurnis

Right now I have a Jim Wolf Technology ECU.

On occasion I get pinging from 3000-4500 rpms. (by the way, this
is where the JWT ECU mods make the most torque gains).

First question:

Is there a difference between the terms "knocking" and "pinging"?
One way or another, shouldn't the ECU compensate until the symptom stops?

2nd question: I looked in the shop manual (page EC144 thru 146) and it states to check the continuity of the knock sensor but doesn't give a spec. And it says both of the harness connectors should have continuity to ground which also doesn't make much sense to me.

Sonic

Knocking=pinging. The engine will detect the pinging and retard timing to reduce the knocking, with reduced power as the result.

I believe the spec is somewhere near 550, but don't quote me, I don't have the manuals with me. You disconnect the knock sensor from the wiring harness, and probe the two terminals. It is the only connector in the area that has only 2 wires attached to it.

Daniel B. Martin

Engine knock, fuel knock, knocking, and pinging are equivalent. In some parts of the English-speaking world the term "pinking" is used. They all refer to the same thing.

Ideally, yes. In practice, maybe not. The Engine Control Module attempts to eliminate the pinging by retarding the ignition timing. This strategy may fail if ...
- the Knock Sensor is bad, so the timing is not retarded.
- the problem is so severe that the pinging remains, even after the ECM has retarded the timing as much as it is allowed.

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.

The manual says you have to remove the intake manifold to replace the KS. However, I think that a person with good dexterity and a 14mm ratcheting box wrench could replace the KS without disturbing the manifold.

Important note: the dealer can do a more thorough test with his CONSULT electronic tester. The resistance test described here is a useful but limited test. A Knock Sensor which fails this test is definitely bad. However, a Knock Sensor which passes this test is not guaranteed to be good.

bill99gxe

iTrader: (1)

Daniel's having to repeat himself again, which I don't like. The trouble shooting info is found in this thread:

http://forums.maxima.org/showthread....threadid=45274

and could have easily been located by searching for "knock sensor" in the 4th gen forum.

Sonic

Bill, I clicked on that thread, and you were the only one posting in it. Were you having a conversation with yourself?

bill99gxe

iTrader: (1)

Yes.



I often have conversations with myself because no one else is listening.....then I start hitting my head against the wall.

The nightly codeine Tylenol makes it all better, though.

chris j vurnis

O.K.

I checked out my knock sensor... and oddly enough, I can't find a single harness anywhere in the engine that has any kind of connector number labeled on it !!

So I found the knock sensor and followed the wires out to the mating connector. I measured across the terminals of the knock sensor itself and got an open circuit.

I didn't measure each pin to chassis but wouldn't I get some kind of reading on the sensor itself ???

Daniel B. Martin

The resistance specification between pin #2 and ground is the only one I found in the factory service manual.

My (admittedly incomplete) understanding of the Knock Sensor is that it contains a piezoelectric crystal which generates a voltage when subjected to physical shock. As such, it amounts to a special-purpose microphone which "listens" for engine knock. Therefore it is a different kind of sensor than the type which has a wire winding with a measurable resistance.

Pin #1 is not part of the KS signal circuit. It is only the outer shield of a coaxial cable. Consequently I would expect an open circuit between pins #1 and #2. Anything else would compromise the signal from the KS to the Engine Control Module.