I thought I'd put this in a new thread so it's easy to find with the search button. Knock Sensor Ohm Test
1. Unplug connector from harness. Picture below is of the detonation sensor harness, not the engine harness going back to the ECU.
2. Set multi-meter to the appropriate range to read a 500,000+ ohm resistor. On mine its labeled 2M.
3. Probe terminal 1 with the red (+) meter lead, and the black (-) meter lead to ground.a. Result should be about 500KOhms. (Meter Reads .500)
4. Probe terminal 2 with the red (+) meter lead, and the black (-) meter lead to ground.a. Result should be about 500K Ohms. (Meter Reads .500)
The detonation sensor harness connection is located below the throttle cables over the right bank of the engine. It is oriented vertically to the engine, unlike the two connectors below it, which are horizontal.
Knock Sensor Ohm Test
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Q45tech
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Won't work well on Q, since the ground is a shield..[the housing is ground thru the head and the shield floats at the KS end.......in order to process the self test, the ground is thru the mounting bolt. So you can't cheat and not mount the knock sensor somewhere to metal ground.
Measure between a terminal and the brassy bottom plate!
The mounting torque is critical in exact sensitivity.
Measure between a terminal and the brassy bottom plate!
The mounting torque is critical in exact sensitivity.
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Q45tech
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No I'm saying you must measure the ground [metal washer at bottom of KS and the other terminal as this is the way the ecu looks at the sensor.
Anyway measure the resistance BETWEEN the connector on the passenger side of engine and chassis ground say the plenum or something that is attached to engine or even the battery negative terminal............hope I'm being clear that the 2nd terminal on the KS is not connected to anything in this application......ground return is thru the mounting bolt. The shield floats at the KS end.
Measuring the resistance is a crude test, the KS can still be bad [bad frequency response/sensitivity] if it reads right but has cracks in the plastic.
Anyway measure the resistance BETWEEN the connector on the passenger side of engine and chassis ground say the plenum or something that is attached to engine or even the battery negative terminal............hope I'm being clear that the 2nd terminal on the KS is not connected to anything in this application......ground return is thru the mounting bolt. The shield floats at the KS end.
Measuring the resistance is a crude test, the KS can still be bad [bad frequency response/sensitivity] if it reads right but has cracks in the plastic.
But isn't the metal washer ground at the bottom of the KS at the exact same potential as the rest of the vehicle ground? Measuring between the harness and, say, the battery ground should measure the resistance of the sensor, the harness and the fasteners all in series--identical to what the ECU sees, minus the main engine harness.
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Q451990
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Q45tech wrote:No I'm saying you must measure the ground [metal washer at bottom of KS and the other terminal as this is the way the ecu looks at the sensor.
Anyway measure the resistance BETWEEN the connector on the passenger side of engine and chassis ground say the plenum or something that is attached to engine or even the battery negative terminal............hope I'm being clear that the 2nd terminal on the KS is not connected to anything in this application......ground return is thru the mounting bolt. The shield floats at the KS end.
Measuring the resistance is a crude test, the KS can still be bad [bad frequency response/sensitivity] if it reads right but has cracks in the plastic.
Ok...that makes sense. The Ohm test is mostly just to tell if the circuit is open or the sensor is completely bad.
Will bad frequency response or poor sensitivity be detectable by the ECU? If not, what are the side effects - I assume detonation that goes uncorrected by the ECU?
Heath
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Q45tech
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What I do is measure the resistance and tap the bottom with a hammer to make sure the resistance returns to normal. The tapping will generate a voltage which changes the meter reading but it should come back to 550,000 ohms. If stable.
What good is having a KS that doesn't proper detect knock so that the ignition advance is the greatest it can be to maximize efficiency.
As we know the JWT ecu gains all its power increases from a 3-4-5 degree advance [22-23>26-28] and a 5%>10%>15-16% enleanment of the AF [peak injection time drops from 11 ms [4,000 rpm] to 10 to 9.6 at redline. As you lean the mixture you need more advance to optimize burn time........richer less advance but less peak heat at the correct moment!
What good is having a KS that doesn't proper detect knock so that the ignition advance is the greatest it can be to maximize efficiency.
As we know the JWT ecu gains all its power increases from a 3-4-5 degree advance [22-23>26-28] and a 5%>10%>15-16% enleanment of the AF [peak injection time drops from 11 ms [4,000 rpm] to 10 to 9.6 at redline. As you lean the mixture you need more advance to optimize burn time........richer less advance but less peak heat at the correct moment!