daddymikey1975 Wrote:I'm certainly no electrical engineer but I would LOVE for someone to try a few tests as I don't have a PWM... most engines DO have a Camshaft Position sensor, or a Tach signal, or if one was unable to find a tach signal, the the UN-common wire at a fuel injector would suffice... here's where I'm taking this...
Would it be possible to use the Fuel injector pulse (also controlled by the computer's PWM for fuel delivery) or use the Tach signal or the Cam position sensor to produce a voltage, or a pulse that can be fed into the input of our PWM's to control the Duty cycle automatically ?? I'm still not understanding the individual parts of the PWM circuit, however I do know what one is, and what it's for... I DO know that the tach signal is pulsing DC voltage, but if you measure it with your meter on DC it's USUALLY between 1 and 4 volts depending on engine RPM.. this varying voltage COULD POSSIBLY be the input voltage in place of the rheostat to control the duty cycle...
anyone with a PWM think they'd like to undertake this challenge?? if I had one I'd try it in a minute...
anyone else think it could work ? we'd need a high impedance circuit so as not to affect the vehicle operation, but i think we could 'read' that varying voltage and use it to our advantage instead of a throttle linkage connected to a var. resistor...
(OR what about using the TPS sensor that's already there?? parallelling off of it?? just another idea for throttle position..)
anyhow, thanks for the advice/replies.
mike
Regarding the pulse for fuel injectors, this can vary for different car makes, and different fuel types, petrol (gas) or diesel. Some use a single pulse for all injectors, Some injector systems are pulsed in individually, some in pairs, and some in groups of three (6 cylinder engines) and some engines pulse all injectors simultaneously. Depending on make you could adjust the pulse count to suit and set pwm accordingly.
I doubt very much whether rapid acceleration, and deceleration, as in stop/start driving would make for accurate tracking with HHO/gas ratio with changing RPM. There always seems to be a delay in change of rate of HHO production when PWM is adjusted.This is why most users aim for a ball park setpoint, often referred to as the sweet point, when setting up PWM, EFIE etc, where there might be different preferred setpoints for town or highway driving.
It would be possible to set up a compromise/predictive algorithm if a processor or microcontroller were used to oversee this method of varying HHO with RPM, and control PWM output, but even this would never be 100% spot on all of the time.
Regarding reading from high impedance sensor circuits, it is easy to set up a high input impedance buffer using an op-amp configured as voltage follower. This typically draws micro-amps from the circuit being monitored.
Note that you can use a pulse train, applied via a resistor to a capacitor to generate a varying voltage, which you theoretically could use to drive your pwm. However, bear in mind what I mentioned previously regarding apparent lag in rate of change in HHO production.