Injection Timing

[John Dickens]

Does anyone know whether the Motronic system on an R1100RT produces a timed injection pulse or a continuous flow?

 

As a secondary enquiry if it is timed does anyone know at what point in the engine cycle it injects

[4wheeldog]

My understanding is that it is pulsed (As are all electronic fuel injection systems) but not timed. Both injectors are pulsed regardless of timing of the intake/exhaust cycle.

[T__]

Does anyone know whether the Motronic system on an R1100RT produces a timed injection pulse or a continuous flow?

 

As a secondary enquiry if it is timed does anyone know at what point in the engine cycle it injects

 

John. It is a pulsed injection system related to engine RPM but not really synchronized with anything like intake valve opening.. It pulses both injectors together & on every stroke so one injection pulse is on a closed intake valve on the non firing cylinder.. Not real high tec but works & is simple..

 

Definitely not a sequential injection system.. Not only that but with only one 02 sensor, both injectors (cylinders) are fueled to a common 02 signal (real low tec)..

 

Twisty

 

[John Dickens]

I love this forum. That's just what I needed to know. Thanks very much.

 

I'm thinking of injecting my 1989 Moto Guzzi Cali III using Airhead throttle bodies and a Megasquirt ECU.

[flars]

"It pulses both injectors together & on every stroke so one injection pulse is on a closed intake valve on the non firing cylinder"

I have always wondered about this. Since the injector is pulsing during the intake stroke on one cylinder, it would also be pulsing on the other cylinder's power stroke. Therefore, it seems logically to indicate that each pulse only provides half the intake charge, i.e. the previous pulse pre-charged the intake tract during the power stroke, and this pre-charge gets sucked into the cylinder along with the actual intake charge generated by the pulse during the intake stroke...

Seems like a potential air pollution nightmare.

Two strokes are so much easier to understand.

Correct thinking, or does my head hurt unnecessarily?

[Boffin]

Not really a nightmare, there is not much time for the fuel to dissipate - at idle, say 1000rpm, each complete revolution takes 60 milliseconds, or one induction event every 120 milliseconds. So at a typical cruise of 3000rpm, there is an induction event every 40 milliseconds - not a lot of unburnt hydrocarbons to escape in that timeframe.

 

Andy

[T__]

Flars, it sure isn’t optimum as far as mixture atomization goes but most auto applications prior to sequential injection functioned the same as well as all carbureted intake systems..

 

Probably not nearly as much of a problem emission wise as using only one 02 sensor or not using 2 spark plugs per cylinder.. Lots of uneven burn on the early boxers with single high spark plug.. On some applications (non BMW) the fuel management has gone to more but smaller injector spray holes in the injector tips to get finer fuel atomization to keep the fuel suspended in the air stream..

 

Twisty