why 2 hall sensors?

[how much]

probly one for Steptoe...



why has my bike got 2 hall sensors?


mines a twin spark..

my mate's is a single spark..


both have 2 pick-ups!


the sensors are at 180deg crank rotation..

i would only need the sensor at TDC to fire the ignition..

why would i want one at BDC

does the second one trigger the rev counter or something??


i am fooked if i know


thanks

how much

 

[MattW]

One sensor triggers the ignition (using a wasted spark on the exhausting cylinder), the other triggers the fuel injectors.

The injectors get away with their 'wasted' injection by delivering half a 'shot' a cycle, so the cylinder actually 'ingests' a full charge on the induction stroke.

I'm pretty sure that's right, but Steptoe can savage me mercilessly if I've got it wrong

cheers
M

 

[how much]

that would make sense! thanks Matt..

how much

 

[DaveGSCymro]

One sensor triggers the ignition (using a wasted spark on the exhausting cylinder), the other triggers the fuel injectors.

The injectors get away with their 'wasted' injection by delivering half a 'shot' a cycle, so the cylinder actually 'ingests' a full charge on the induction stroke.

I'm pretty sure that's right, but Steptoe can savage me mercilessly if I've got it wrong

cheers
M

Injectors are normally triggered by the engine ECU. If you were injecting any fuel on the exhaust stroke this would bugger the cat staight away.

 

[MattW]

Injectors are normally triggered by the engine ECU. If you were injecting any fuel on the exhaust stroke this would bugger the cat staight away.

I've been given to believe that the ECU gets its injector timing impulse from one of the hall sensors. Obviously it uses several other inputs in conjunction with the map to determine fuelling requirements (the amount of fuel delivered being metered via the injector 'open' time). The other sensor delivers the timing impulse for the ignition.

Now for the bit I'm less sure about....
A shot of fuel delivered into the throttle body on the exhaust stroke shouldn't matter as the inlet valve is shut so it won't be aspirated by the engine until the inlet valve opens on the induction stroke (when the other 'half' of the charge is injected).

Just what I've been told - I stand to be corrected of course

M

 

[how much]

Injectors are normally triggered by the engine ECU. If you were injecting any fuel on the exhaust stroke this would bugger the cat staight away.

am i back to square one



how much

 

[D6]

on a jap bike, its so you can get the timing more accurate

 

[MattW]

am i back to square one

how much

Nope

2 hall sensors on the sensor plate.
1 for ignition, 1 for injectors.

If it makes it any more believable, I'm pretty sure I've also seen this written by Steptoe on here...

Matt

 

[Womble]

It makes sense - the injectors need to be working at the bottom of the stroke when the valves are open, and the ignition has to happen around the top of the stroke, when the valves are closed. The only way you're going to have that working correctly and accurately is to have a sensor for each.