timing - how is it adjusted?

[nex]

there is always talk about the ecu retarding/advancing and adjusting timing, also shown via concult on ecutalk/datascan, but how does it do this as the spark system is driven by a dizzy cap?crank speed, cam speed and thus rotor and dizzy speed are all directly related, so how does the ecu adjust the timing? just curious as I dont get it :doh:

sorry if its a daft question.

 

[simpulsar]

you can un-do the dizzy housing and twist the housing to advance or retard the ignition timing

 

[nex]

I realise that, however during a consult session the timint will change and people will often say its th ecu changing it...........thats what i dont get...

 

[olliecast]

I realise that, however during a consult session the timint will change and people will often say its th ecu changing it...........thats what i dont get...

you have an ignition timing map on your ecu which corrisponds to rpm / engine loading. It changes across the rev range as the more load the engine is under the less ignition advance it`ll run (to prevent det)

 

[steve963]

can it do this because the rotor arm contact is 'wide' if you know what i mean, I guess it probably covers about 20degrees as its about 1cm wide

so the spark can jump from the front edge of the rotor arm or the back end

 

[Fusion Ed]

1deg cam = 2 deg crank.

The distributor is two things, a cam sensor and a HT distributor, and yes because the rotor arm is wide it can fire at any given point to advance or retard the timing

Ed

 

[nex]

Makes sensee, cheers both!