knock sensor

[Seight-v8]

hello all,

Noticed yesterday one of my knock sensors is making a high pitched whistle noise when the ignition is turned on.

The other side one is fine though.

Its a v8 engine with 2 knock sensors....

Cant say i have noticed this before.

Does this mean is knackered.

anyone suggest anything.

cheers

scott

[rob@vems.co.uk]

Check the voltage on the lines of the sensor - its a piezoelectric device (tweeter) so it may be getting a voltage stimulating it.

[Seight-v8]

cheers rob you were right...

on the side that is making the noise, it has 3.77v supplied to it.

on the other side its getting 0.5v which then decreases to zero over a few seconds.

i am not sure what should actually be supplied......i presume up to 5v....but again dont know how these sensors work.

Looks like i may only have hardware installed for one channel, so this might mean why other side shows 0v.

cheers

scott

[Seight-v8]

ok so i have now installed the second knock (channel 0) hardware into my ecu so i can use knock sensors on both V8 banks.

As per the info on the wiki.

What confuses me is....one side has 0v when tested, the other side now has 1.5v supplied when tested.

Still not sure which is correct.....is the voltage generated by the knock sensor....or by the ecu and supplied the the sensor?

If so why does one side have 1.5v when the ignition is on and the other doesnt.....problem somewhere?

Not planning to use knock yet, just want to make sure hardware works, so i can put my car & ecu back together.....to drive it.....otherwise will have to disassemble everything again later.

cheers

scott

[rob@vems.co.uk]

I am guessing that one channel has a pull-up resistor on the channel.

Personally I would pull the pins out at the EC18 and measure the voltage between each knock pin and ground - then you can ensure that the loom is not causing anything to pull-up and you can get on with making the car run.

Rob

[Seight-v8]

cheers rob,

its been like that for over a year now, but i always ran with knock turned off....i only noticed one day sat in the car with the ignition on and i could hear a strange noise.....

for some reason its channel one, and doesnt happen on channel 0.

I may decide to use knock one day, when but at the moment i have no idea how it works.

will try and test it in the next few days.

I've been around the block in my car this year, but fitted a new carbon plenum chamber.....so have to re-do the fuel table.....before hitting the MOT & open road.

thanks

scott

[JRD McLAREN]

wow 3 topic about Knock sensing ..

so is there anybody, who have working knock detection ..??

I'm tying to do some test with Knock sensing, try to use Bosch and Siemens 2wire sensors
Knock Gauage values are from 500-650 at normal and high RPM, but no Knock Action ..
try to test it on 35deg pre-ignition at 1500rpm, 45deg@3000rpm, but nothing happened..  (I hope)

fw is 1.1.81, knock is on analog0 (ec18-1), pull-up resitor is desoldered, voltage is aprox 1.8-1.9V..

THX..

[boostd audi]

im trying to get my knock working as well