knock sensor

[rein]

Hi all,

I am building an electronic ignition for my 1098 saloon. I need a knock sensor to complete it. I checked the local car wreckers but wasn't really sure what a knock sensor lookes like. I assume it is positioned on the cylinderhead. But so are other sensors. Most cars at the wreckers are Japanese, although I did see Fiat and Rover cars with engine management systems. Do all engine management systems use knock sensors? Does anyone know where on the engine the knock sensors are located? Maybe a universal one at the parts supplier isn't very expensive?
Cheers,

Rein

[chickenjohn]

Just use the standard points, condensor and coil, its a very reliable system as standard. No need for complex electronics!

[rein]

I know. I am just combining two hobbies in one.

[alex_holden]

Sounds like an interesting project. Can you provide some more technical details on the electronics?

[MoggyTech]

Hi all,

I am building an electronic ignition for my 1098 saloon. I need a knock sensor to complete it. I checked the local car wreckers but wasn't really sure what a knock sensor lookes like. I assume it is positioned on the cylinderhead. But so are other sensors. Most cars at the wreckers are Japanese, although I did see Fiat and Rover cars with engine management systems. Do all engine management systems use knock sensors? Does anyone know where on the engine the knock sensors are located? Maybe a universal one at the parts supplier isn't very expensive?
Cheers,

Rein

The Knock Sensor if usually a Piezo Crystal designed specificaly for a certain engine type. It will not work on the 1098 engine unless you know the specific frequency chart for the KS, and can find or map, the knock harmonics for a 1098 block. To do this properly, you will need a low amplitude Knock Sensor for each cylinder.

[Rob_Jennings]

why not look at the configuration of the last of the old minis, they had MPI so I guess they must have a suitable sensor somewhere for that sort of measurement?

[youngun]

Im building an electronic CDI ignition for my two stroke moped, it utilises an opto sensor to fire at the correct time, and i can download an ignition map from my laptop to the CDI to allow me to alter timing angle's at different RPM's to allow for certain types of performance throughout the rev range. However, im still argueing with the download software, but the opto sensor etc do work along with the pre-set auto advance/retard.

[bmcecosse]

The MPi Minis have relatively simple lectronic ignition with no dizzy - but it's just done from crank position sensor, air flow and temperature, throttle position and readings from the Lambda sensor in the exhaust - no 'knock' sensor is used. Mini lads do report great engine improvements when fitting the Megajolt system which is completely mappable - but again no knock sensor is used.

[rein]

The knock sensing on this electronic ignition is rudimentary. It senses frequencies between 4.8 kHz and 6.4 kHz and only for the "lower" revs up to 4000RPM. You set the advance curve so engine knock only occurs under unusual circumstances.
The project is not my own design. It is a Silicon Chip project sold by Jaycar.
You can load the advance curve you need for your engine in the microprocessor (with a basic "handcontroller") and it includes (optional) vacuum advance curve. So no more need for mechanical advance.
I suppose any knock sensor will do.
At the moment I am using a Fiat Uno electronic ignition I build in a Lucas distributor. It wasn't easy to get the advance curve to correspond with the suggested factory curve by changing the springs on the advance mechanism. Yet I am pleased with the end result and want to take it a step further.

[bmcecosse]

Sounds very intereresting - and yes all modern cars use a knock sensor to absolutely maximise the ignition advance. I can hear my Vauxhall engine 'just' pinking for a second when I put when I foot down. But none of the Mini lads bother with the knock sensor - they do seem to map the advance by running the car on a rolling road and setting the advance there. Fine if you have easy access to a RR I suppose!