Actually, that's not quite the case, but it is what I WANT to do.lapuwali wrote:
The plunger is NOT directly controlled by the PWM valve on CIS-E. The only thing that's attached to the plunger is the airflow plate. The PWM valve alters the control pressure, which alters the air/fuel curve by altering the resistance to movement of the plunger by the airflow plate. Controlling this valve IS the way to control fuel flow while retaining the airflow plate (which a previous poster listed as a goal). This would not be at all hard to do.
On CIS-Lambda, the lambda valve/pwm valve trims mixture by manipulating pressures within the chambers in the fuel distributor (just found my Probst book). What I want to do is replace the Control pressure regulator with a PWM valve.
On a CIS system, injector flow is a funtion of the position of the plunger. Gross position determined by airflow, with the force of the airflow on the meter plate counterbalanced by the control pressure on the other side of the plunger.
Reduce control pressure:
- counterbalance force on the plunger is reduced
- resisting force on the plate is reduced
- the arm moves
- plunger moves
- equilibrium reestablished.
Now, what if we replaced the air flow plate and arm assembly with an appropriate sized spring? Size would be such that, at highest control pressure, spring is fully compressed, plunger is at it's bottom stop, and flow is minimum.
Now, as control pressure is decreased
- the spring expands
- the plunger moves up
- flow increases.
How do we make the control pressure fall? By increasing the frequency valve duty cycle. The MS should use a similar fuel map driving the frequency valve as driving standard injectors - as load goes up, valve opening time goes up.
What I'm proposing is different from T3 and chois. Where chois proposes keeping the appearance, it is the appearance that I specifically want to alter. I want to get the advantages of CIS in a smaller package with more mounting options. That means ditching the air flow meter.
R2.0