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cam belt sensor
cadebytiger - 20/7/07 at 07:01 PM

a friend of mine had the cam belt sensor changed in her car..

What does the cam belt sensor sense?

is it an ignition/injection timing thing?

Thanks

Rupert

NeilP - 20/7/07 at 07:07 PM

It would sense the cam position hence allowing each cylinder to spark at exactly the right point on its 720deg cycle? - As opposed to a wasted spark system as used on a lot of EFI systems that sparks twice in the cycle as it senses off the crankshaft (one of the two sparks being wasted)...

It could be to tell you that you car is no longer working if it juddering to the side of the road was not enough of a clue...

To tell you that it's running loose? Doesn't sound like a great design...

It doesn't actually exist but it's a way that garages hoover money out of unwary punters...

[Edited on 20/7/2007 by NeilP]

MkIndy7 - 20/7/07 at 07:10 PM

I think there called Cam "phase" sencors (or similar wording)

There for cars that run sequential injection i.e they only fire the injector when that cylinder is on the inlet stroke.

They need to know exactly where the camshaft is as apposed to a standard system where it injects even when the valve is closed.. where the crank position sencor provides a close enough signal.

MkIndy7 - 20/7/07 at 07:14 PM

quote:
Originally posted by NeilP
It would sense the cam position hence allowing each cylinder to spark at exactly the right point on its 720deg cycle - As opposed to a wasted spark system as used on a lot of EFI systems that sparks twice in the cycle as it senses off the crankshaft (one of the two sparks being wasted)...
[Edited on 20/7/2007 by NeilP]


Didn't/not sure they use it for that, the wasted spark isin't a waste (if anything its benificial), whereas fireing the injector only when the inlet valve is open is said to be more economical or better power and more emission friendly

martyn_16v - 20/7/07 at 07:33 PM

Plenty of newer engines use coil-on-plug ignition nowadays, which does need to know cam position

cadebytiger - 20/7/07 at 11:31 PM

thanks everyone! I knew you would know!