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Knock Sensor Fitting!


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HI guys - i need some fitting instrucitons/guide for my garage to fit a replacement knock sensor as they cant seem to find it - can anyone help!

 

Nissan can do it but have said they will charge me £85 just to diagnose the problem first as they cannot rely on another garage despite the fact my garage has an ecu printout with the fault!! :rant:

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The knock sensor is located at the back of the engine, bolted to the block inbetween the thh heads, underneath the lower Plenum.

 

They will need to remove the upper and lower plenum to get to it. Budget for about £400 labour plus price of the knock sensor (150'ish depending on where you purchase). That is why it is so popular for people to just bypass it with a 1megohm resistor.

 

Btw - It may not be the knock sensor. the Fault code can mean knock sensor failure or a poor connection in the loom from the ECU to the plug, and then from the plug to the Knock sensor.

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Would the garage be able to check the wiring then? Dont want to get this done unless necessary - oh and Nissan have advised it would be 2 hours labour £140+VAT plus £70+VAT diagnosis plus the part

 

have heard that bypassing is not a good idea? :confused:

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yes, faulty wiring will cause safety mode in the same way faulty sensor will.

 

They will need to check resistance between the loom. The Plug for the Det sensor is at the back of the engine bay, in about the middle just behind/above the plenum. Its a 2 pin grey plug. That plug connects the loom to the ECU and the loom the the Knock sensor.

 

Bypassing means the car will not be able to sense detonation and protect itself...you would have to do it yourself (its usually quite audible). Another point though is that a properly running car on correct fuel should not get detonation and the Sensor only reads below 3000rpm as above that range engine noise is too much.

 

Be very wary of the Nissans Dealers quote, because there is no way in the world they can do it in anywhere close to 2 hours ! As a general rule Nissan dealers do not have a clue when it comes to the 300zx ! They will also charge you about £200 for the sensor.

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if the engine is detting ud be better off checking timing is not too advanced and if its correct just retard it a few degrees and make sure its not over boosting then do the bypass resistor until engine comes out, if the garage had to remove the lower plenum then it would also be adviceable to have new timing belt/waterpump fitted as wellas the timing belt will need to come off to remove lower plenum as the idler is bolted on the lower plenum

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if the engine is detting ud be better off checking timing is not too advanced and if its correct just retard it a few degrees and make sure its not over boosting then do the bypass resistor until engine comes out, if the garage had to remove the lower plenum then it would also be adviceable to have new timing belt/waterpump fitted as wellas the timing belt will need to come off to remove lower plenum as the idler is bolted on the lower plenum

 

Its not detting bud, or at least he didn't say it is.

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thanks for info guys - are you saying that that bypassing is safe then? my car is also running very rich.

 

the garage picked up the knock sensor fault, reset it then it came on again

my cars been bypassed for about a year now with no harm,first you need to be 100% sure thats its going into "dett" because of a faulty sensor or plug and not because of another reason which could be more costly like a too lean afr or wrong octane hth ;)

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