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How does a Detonator sensor work?


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Hi guys,

 

How does a detonator sensor work?

I cant find any detailed information about it. All I can find in the 300zx manual (cd) is a small paragraph on knock sensors. Is a knock sensor and dett sensor the same thing?

 

What is the dett sensor actually sensing? Is it heat or knocking?

 

Also, how much is it to buy a new sensor?

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dett sensor = knock sensor

 

Its basically a little microphone, setup to recognise the sound of detonation.

 

It only works below 3500rpm (or 3000rpm..cant remember) as engine is too noisy above this point.

 

When it senses(hears) detonation it sends signal to the ECU to retard ignition and boost pressure preventing further damage.

 

I believe new sensor and harness is about £100. Although its a fair bit of labour to replace. When they fail most will bypass it until they can get it done at the same time as other major work.

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dett sensor = knock sensor

 

Its basically a little microphone, setup to recognise the sound of detonation.

 

It only works below 3500rpm (or 3000rpm..cant remember) as engine is too noisy above this point.

 

When it senses(hears) detonation it sends signal to the ECU to retard ignition and boost pressure preventing further damage.

 

I believe new sensor and harness is about £100. Although its a fair bit of labour to replace. When they fail most will bypass it until they can get it done at the same time as other major work.

 

Thanks for that :bow:

 

Mine needs to be replaced. I get intermittant boost. To start with I get 0.7 bar, when the engine gets hot it runs 0.5 bar. My ECU gives the error 34. From what I have read, these are the symptoms of a faulty dett sensor.

 

However, what is there to go wrong in a dett sensor? If it is faulty, surely I should be getting 0.5 bar boost all the time?

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Thanks for that :bow:

 

Mine needs to be replaced. I get intermittant boost. To start with I get 0.7 bar, when the engine gets hot it runs 0.5 bar. My ECU gives the error 34. From what I have read, these are the symptoms of a faulty dett sensor.

 

However, what is there to go wrong in a dett sensor? If it is faulty, surely I should be getting 0.5 bar boost all the time?

 

Could be bad connection at the det sensor, or at the connector at the top of the enigne , or in the harness somewhere.

 

Unplug the connectors, and check for corrosion and clean.

 

You can find it here (also tells you how to bypass it) : http://zhome.com/ZCMnL/PICS/detonationSensor/detonationSensor.html

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Guest DaveMan

quote "Its basically a little microphone, setup to recognise the sound of detonation"

 

That's somewhat a simplistic working description, the sender unit is actually made up of a pietzo quarts receptacle which has been designed to produce a small electrical output signal when knocking / pinking occurs at the prescribed frequency, this output is generated by the the pietzo quartz occilating and produce a signal that the ecu responds to.

 

Daveman

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the sender unit is actually made up of a pietzo quarts receptacle which has been designed to produce a small electrical output signal when knocking / pinking occurs at the prescribed frequency, this output is generated by the the pietzo quartz occilating and produce a signal that the ecu responds to.

 

Daveman

 

Correct!!! Good description!!! :bow:

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If a boost controller was fitted, which would also mean a new chip i.e. JWT. I take it the ECU no longer can control the boost, thus a detonator sensor would become useless as the ECU cannot put the car into safety mode! Am I correct?

yes but a 25p 1megohm resistor will do the same job bud,ive just had the same probs as yours as in intermitent safe boost when hot so just hard wired one in :)

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What does dett sound like and when would you get it, I have a noise that sounds like tappets at around 2k when the engine is warm and was wondering if thats what it was.

could be but only when the motor is on full load

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Guest Eisegerwind
That's somewhat a simplistic working description, the sender unit is actually made up of a pietzo quarts receptacle which has been designed to produce a small electrical output signal when knocking / pinking occurs at the prescribed frequency, this output is generated by the the pietzo quartz occilating and produce a signal that the ecu responds to.

 

Yes, a microphone!

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iff you can feather the throttle till your past 3500rpm then nail it your dett sensor should,nt click in because after this rpm the engine produces to much noise that is out of the freqency range for the sensor to pick up (hear)

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