Hi
I ran into a new problem with my current manifold and "extended VEMS" project.
As the engine will have 6 ITB, did I design the manifold to use a Keihin NEMA14 steppermotor that come from a Triumph motorcycle. Instead of beeing a "air valve" do they simply change the butterfly valves, idle position in the TB's slightly (like 4% TPS in idle when cold)
But.... first of all the Stepper have 10ohm static resistance, så will draw ~1.4 Amp on 14v dc. The Stepper chip in Vems can only handle 1A continuously. So be aware of stepper resistance, must be 20 Ohm or higher to be safe.
Another topic, and really the biggest one. In the Vems software are the stepper variabel perhaps only 1 byte, allowing the "steps" to go from 0 to 255, most stepper motors are 200 steps / rev, equal 1.25 rev on the motorshaft. With a 1mm/rev lead screw in the Keihin motor, did it not really solve my application. The stepper it self is a captive type with 5mm stroke, so I designed the idle stop system based on 4mm travel.
So back to the drawing board, need a new motor with a 4mm pitch lead screw, and that most for NEMA17 or larger motors, and my application is designed based on a NEMA14. NEMA14 liniar motors mostly come with TR5x2mm lead screws.
Can anybody request the SW guys to look into the option og increasing the variable in the VEMS software, to increas the "step range" from 256 to eg. 1024 or higher. This will increase the usability of stepper motors.
I could imagine that the supercharged guys could use some more steps to control butterfly valves for blow of or bypass purposes, or even for controlling VNT turbos.
And building a PWM -> stepper controller in my netduino car computer can easily be done, but it can't be true that I have to continue doing work arounds on VEMS short commings :-) ( I already have a protocol debugger to drive the AFR meter in my dash, and is considering to build my own injector stagging setup as Vems can't drive 2x6 injectors)
And my wish, make the SW open source. And adding a new HW platform with a processor board, and stacked expansion boards in a modular setup.
