I would be interested to know. Have you tried driving the TB with a bench top power supply? Something you can control voltage and or see current? Or just with the pwm?
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I donât have a proper power supply, Iâve only tried with the PWM.
I really should get a benchtop power supply for stuff like this.
Edit: Iâm very illiterate of electronics. Diagrams may as well be magic sigils to me.
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Hi Cody, do you have a digital multimeter ?
When so, you can put it in series between the TB and your PWM to measure the amps.
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Im just curious what it really takes to drive your TB.
Like koen said sometimes a pwm can be deceiving.
So can you open your TB with 3v as in 2 D cell batteries in series? Or fully open with 4.5v (3 D cells in series)
Ok, i re-read your posts and checked out the link to your pwm.
If your TB is 5v it makes sense, what your saying about powering the pwm modual with 12 volts and it being touchy and fully opens with bottom quarter to half turn of pot.
It also makes sense what your saying about driving it with 5v.
When testing and learning as i built my controler. I saw some of the same things. And it all comes down to trying to drive a motor one way with spring return.
I would get (one specific) degree of opening at a specific pwm input while opening the TB. And it would require a whole different pwm input to get the same degree of open when returning from WOT position.
Sorry, that is confusing me and im typing it.
It comes down to trying to turn a motor only in one direction and relying on the spring to return the valve. It is going to require a different input value depending on if valve is going from closed to open or open to closed.
Thats why i went with a motor driver (H bridge) so i could drive motor in both directons. And then used the posistion sensors on the TB as feedback to make sure the TB was where i wanted it. And was always in the same position at a specific point on the pot rotation.
I suppose it could be done without the H bridge but would still require the feed back from the TB position sensors. And a microcontroller (arduino)
At least with a TB that is driven with motor, not stepper.
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Set at the Ohms? At the 20k setting the TB begins to open at .90~1 and is fully open at around 2, but it jumps instantly from 2 to 2.5
Sorry I misread let me check again at Amps.
Edit: at the Amp setting of 200m it starts moving at around 10.0 and is fully open at what seems to be 20.0 but it jumps from 15.5 to 20 instantly.
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The spring return driven TB requires an amps limited/controlled 12 V voltage, where as the other wires are from/for the TPS.
I use this one for many purposes, it has an Led readout in from 0 to 100% (duty cycle )
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Hi Cody, measure at 12V, minimum setting from the pwm, it should be around 500 Milliamp.
Set your amps meter at a higher measuring level
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The prices as you see in my picture are not in dollar ⌠Just divide by 35
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12v supplied, measuring from positive of input and positive of output with meter set to 10A, starts opening at .03 and is opened fully at .25
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There you are, you need a different PWM to get it at a range low enough for the milliamps or, you can try to replace the potmeter with a value higher then now
The coil spring tension requires about 3 watts to keep it open, or max .25 amps ( wire strength is the limiting factor)
At low voltage but same watts the amps go up, but the wire inside the motor windings canât handle the higher amps
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The only other potentiometers I have on hand are 10k and 5k, do you think the 10k will be just about right considering itâs 1/10th of a 100k?
Or would I need to go to a 200k? Like I mentioned earlier this is not intuitive for me.
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Hi Cody, it looks that you need a 200K or an additional 100K resistor in series with your current potmeter
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Okay so I have soldered in a 250k potentiometer. It is functioning better and is less touchy but it uses maybe 1/4 of the rotation of the knob just like the 100k. My goal was to have it use the entire rotation. I have a 500k potentiometer, should I try going up even further, or should I go back down to say 50k?
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It seems like the throttle body uses a DC motor working against a spring to set the throttle position. The torque to compress, or in this case, rotate the spring comes from the motor. For a DC motor, the torque is pretty much proportional to the current. More current means more torque, more torque means more throttle opening. The motor will have some resistance that will limit the maximum current for whatever voltage you use. You just need enough voltage to get the motor to the current needed to fully open. The PWM will reduce that total current. Pulse width of 1/2 means approximately half the effective current. 10% pulse width, 10% current, 10% throttle opening, again approximately, since the world comes with friction whether you like it or not.
The pot on your PWM controls the pulse width (how long itâs off versus how long itâs on). Depending on the particular circuit, it may be wired as a potentiometer, that is, voltage `divider. If it is, a different pot resistance wonât make much difference. Adding resistance in series with one end could reduce the maximum pulse width, current, and throttle opening, giving a less touchy control. For a 100k pot, adding 100k in series should limit the pulse width to about half of maximum.
If itâs used as a variable resistor (unlikely since it has three wires running to it) then a different value pot might help.
How much of the rotary range of the pot do you use to go from closed to open on the throttle?
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About 1/4 rotation give or take. I noticed with the 250k that there wasnât a lot of âtake-upâ to get the butterfly to start opening and as I began to turn the knob back down it would follow it instead of holding until I bottom it out.
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Iâm going to resolder the wires to use pin-out females so I can just plug and play with my potentiometers. I bought a variety pack.
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Iâm guessing (and I choose that term on purpose 
) that adding about 200k in series with one leg of the original 100k pot would give you full open throttle at 3/4 of the potâs mechanical range. Since you have more âoutputâ than you need, Iâd put the resistor in the wire that leads to the âhighâ end of the pot.
When you increase the resistance of the pot to 250k, the currents get small enough in the pot that the circuit may not have enough current capability to work as designed.
By the way, going to a 500 mA PWM probably wonât help. The 500mA is a maximum rating. Once you have enough current to supply your load, the behavior (sensitivity, range, etc,) wonât change very much. If someone makes a controller with adjustable minimum and maximum duty cycle (pulse width), then that would be helpful.
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I could try a slide potentiometer and just physically limit the throw.
There has to be a better way to control this motor, though. I donât know the exact pin map for this TB but shouldnât this be able to be controlled by some sort of stepper controller that reads from the TPS?
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You could use an Arduino, or other microcontroller to implement a feedback controller. Read the TPS, convert to position, figure out are far you are from the desired position,change the PWM duty cycle, which changes current, which moves the throttle plate in the desired direction, then do it all over again until the TPS value and position is close enough.
You could let the microcontroller handle the PWM task, and just drive a power MOSFET or the like to drive the motor.
Easier said than done, but not easily said clearly, as I have demonstrated
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I might be better off just making a manual valve de la Wayne Keith and saving this throttle body if I ever get an LS motor that uses this style.
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