Throttle Position Sensor

This might come in handy for switching advance curves in an ignition system. There are ignition units used on Harleys which switch to less aggressive advance curve if loss of vacuum occurs. A switch operated from the throttle cable might be a better answer ?

https://www.linkedin.com/pulse/cable-th ... vid-cherry

Can't you switch maps on the Old Britts ignition?

swooshdave said:

Can't you switch maps on the Old Britts ignition?

Click to expand...

From their description "Two switchable advance curves (maps) are available with each unit." http://www.oldbritts.com/51_150101.html A vacuum switch might be a better route to go versus the TPS, as that would be more indicative of what kind of BMEPs were going on in the cylinders, and what would then be the "better" advance curve to run with. That way, it would switch to a milder advance with a low manifold vacuum (accelerating), and back to more advance with a high vacuum (cruise).

Nathan

This is the unit used on Harleys which has the advance curve changed by the vacuum switch. I've always thought it would be an unreliable way to go because of the pulsing in the inlet ports.
http://www.ebay.com.au/sch/sis.html?_nk ... 7675.m4099

In many applications the Dynatek unit operates with the vacuum switch shorted out, so the advance curve does not change. I don't think it matters much on most race bikes because the need to change to a less aggressive curve probably would not arise unless you are balked and can not change down a gear. However it might make a difference when coming out of a slow corner on full throttle and during clutch starts.

I think on that Dynatek unit that when the vacuum sensing switch is shorted out the less aggressive curve comes into operation. So a throttle position sensor could be used to short the switch at full throttle to give retard when there is no vacuum and the motor is running lean. It would mean that the aggressive curve could be much more aggressive ?