knock sensor sub harness to ground reads 0.583 Mega OHMs so im guessin the harenss is not good ? the sensor is brand new......

im guessin thats why shes been sluggish.......

 

bump.....10 char

 

Nope .58 meg ohms is good.

Thats sufficient for the ecu to read the signal. When mine was bad it read 5 meg ohms.

 

humm......weird the new knock sensor shouldnt be bad, ill tell ya i put the resistor in and felt a difference.......maybe i just wanted to feel a difference and tricked myself into thinking there really was a difference.....

 

what value resistor did you use? I thought most people used a 470k ohm one, which is pretty close to what you measured on your current one.

 

Hmm. Was just about to mail u on this one. I measured that (connector off from) the sensor side connector two pins as the manual suggests. No connection.

So I think Knock sensor is bad.

I installed a pair of one meg resitor (now that means 0.44M) on the connector pins. Dunno, but high end horses scream. Too slippery to test any performance difference. Engine has been running perfect, but higway consumption has always been higher than I expect from a nissan...

What do u say, will this resistor be ok? The NISSAN manual does not give any reference to resistance, says only: connection should be found between a-b on The VG...hehe whatta perfection resistance.

Have to wait an see.

 

I dont see how 2 1M in parallel makes 440k and not 500k, unless you're measuring the actual value and not just the theoretical and there is some tolerance variations causing that.

I'll try to take a look at my knock sensor and measure it tonight since I'll be doing some EGR stuff in there. My KS is only 2 weeks old so it better be in spec

 

True. Measured that in hand, dunno even what the originals woul show on my cheap gauge... many causes for the measurement. Happen to have pack of those one meg, juts tied together and installed. Wanna go now on the higway, but most likely cannot really test...

If Nissan manual does not give any values, I assume that if some kinda soot is there, its gonna be ok...

The VG KS connection is different from VE, right? VE has to be tested against gnd.

 

yes i tested it against ground....i put in a 470K ohm resistor and after driving it a few days there is DEFINITLY a difference. i plugged the KS back in and ecu went into safe mode. Now heres the funny part the KS is nissan and is brand new. The harness is as old as the car. but im measuring 0.583 Mega ohms from the harness to ground. im replacing the harness anyway cause there in lies my power loss. let me tell you the low end on this car is excellent with the resistor in , im actually enjoying 2nd gear stomps again. from 2500 rpm in second i can stomp the gas and break loose the tires. take out the resistor and it stuters and drains power till 4500 then it gets up and goin. its just gotta be that harness...

 

ECU in the safe mode? I have absolut no KS connection and car is working very well, only think that gas consumption is 15% more that should be on highway. )Well now think that acceleration at higway speed is better with the resitor, but its difficult without exact numbers.) That would be in line with the ign advance: idle or low 2000 no big advance, it comes into view at higher rpm.

Maybe smtg wron with your harness. Or just connector pins to ECU are semi floating. The oxidation can be bad even if nothing is seen. My TCU was definitely so, after cleanup the veeery soooft change vanished totally: http://www.cardomain.com/memberpage/748507/14

 

my ecu is fine i had the connector apart when i did some wiring for the remote start and the air fuel gauge.

 

Well installing a resistor will trick the ecu to think that everyting is alright. But in reality the knock sensor has to regularly retard the timming since every engine misfires, it may only have to retard the timming for a very short time, but its protecting your engine from detonation. So it would be normal for the engine to seem a little more powerful when using the resistor. When using cheap/bad gas the KS feedback system has to be incredible active.


Wiking, make sure your ohm meter is capable of measureing at least 10Meg ohms. Also try measureing each terminal at the sub harness to the battery ground.

Edit: actually wiking, I re-read your post. Only one wire is actually being used, the second makes NO connection, its an RF sheilding. Continuity is made through the engine block.

 

- We have only 95, 98 octane available.

- Ohm meter cheapest available, 20M says so... has been accurate on other issues.

- KS wires: Absolut no ohm connection to anywhere. But why should there be in th first place? ...these piezo components give ohm reading only if pressed. Is the sensor pressed inside the KS assy block? And thats why nissan manual does not give any numeric value as the reading can be just anything from zero to heaven?

- RF shield: That what I also wonder from the schema. Why VG is different from VE... The harness on VG has a tst connector where only one wire is connected. The scope pic from it is like this, I do wonder if its working or no? This pic is at idle, at high rpm the signal goes to rnd unmeasurable ripple. Please see also my page to give input if the text is ok... http://www.cardomain.com/memberpage/748507/9:

 

Well the piezo does give an ohmic reading, its around 470k Ohms (at the sensors terminals). You need a signal reading from a working KS to compare what your reading. If you decide to replace the ks, then make sure you get the sub-harness as well.

 

The nissan built assy [pretensioned?] might be so. Off the self basic plain piezo element does not give anythin. Pressing, bending --->u get what u want... its like a "microphone/speaker".

Nissan service manual does not give that value, only says: connection...