Stepper idle motor and the Crank-to-Run Taper Time

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B1ack_Mi16
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Stepper idle motor and the Crank-to-Run Taper Time

Post by B1ack_Mi16 »

Having problems with the Crank-to-Run Taper Time functionality.

Take a look at this video, I've tried several settings, but it seem to me there is no delay in the idle stepper and it goes as fast as possible from the cranking position to the "running" position. This makes for a bit funny idle after startup.

Have anyone else successfully used this with a stepper motor, what can possibly be wrong? Might it be that my setup is that closed valve = 255 and fully open is 0 steps? That the software doesn't calculate the decay rate correctly when the idle stepper is set to Homing direction: Closed?

This small movie shows the problem:
http://s428.photobucket.com/user/B1ackM ... sort=3&o=0
CRSTune
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Re: Stepper idle motor and the Crank-to-Run Taper Time

Post by CRSTune »

It would be much easier to view with a datalog so we can see all the data.

Your cranking RPM is too high (750rpm). Every time your RPM drops below that number, the ECU assumes the engine is cranking, not running, even if it already is. 300-400rpm is a more typical threshold. That means it's flip flopping between the cranking tables and your actual running tables.

Homing direction determines whether the homing steps you choose indicates a closed or open valve. For your settings, after homing for 255 steps, the valve is closed at 0 steps with larger numbers indicating a valve that is more open.

Your cranking and running steps are rather odd. The running steps are higher than the cranking steps when in my experience, the cranking steps is typically higher than the running steps. The theory is that you want the engine to flare up on start up to a relatively high rpm. Then, as the ECU goes from cranking to running, it will lower to your target rpm. In your case, it would start and progressively increase in RPM.
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B1ack_Mi16
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Re: Stepper idle motor and the Crank-to-Run Taper Time

Post by B1ack_Mi16 »

Nothing odd with the steps really. 255 is fully closed, 0 fully open, thats just how it is set-up. I just wired the MS3 Pro into a factory stepper setup.

The problem is that the software states it should fade beteen cranking step at approx 70-80 to running steps more like 150-200 depending on coolaant temp.
This fade procedure should in this case take 15 secs.. well it doesn't. It does the operation as speedy as possible it seem, hence my problem. If I set cranking speed lower, revs fall even faster and it goes to a complete stop instead of how it works now.
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Re: Stepper idle motor and the Crank-to-Run Taper Time

Post by jsmcortina »

:msq:
I can repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

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B1ack_Mi16
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Re: Stepper idle motor and the Crank-to-Run Taper Time

Post by B1ack_Mi16 »

Ok, sorry about that, here is the msg.

https://drive.google.com/open?id=0ByGjL ... W51RURBM1k

How do I log the stepper motor response, maybe I need the registered version of TunerStudio first? I'm really not much into the software yet. Just barely logged some trigger data yet.
jsmcortina
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Re: Stepper idle motor and the Crank-to-Run Taper Time

Post by jsmcortina »

Datalogging is fully supported in the standard version. See the Forum Help Page.

Sounds like your stepper is running backwards. More steps must equal more air for more RPM.

James
I can repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

My Success story: http://www.msextra.com/forums/viewtopic ... 04&t=34277
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New users, please read the "Forum Help Page".
B1ack_Mi16
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Re: Stepper idle motor and the Crank-to-Run Taper Time

Post by B1ack_Mi16 »

Ok. I'll look more into it. Firstly I'll rewire the stepper if there is a requirement that more steps = more opening.

If so that might be solving all the issues, maybe even the other issue I have on the closed loop that's not possible to get enabled at the moment.
B1ack_Mi16
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Re: Stepper idle motor and the Crank-to-Run Taper Time

Post by B1ack_Mi16 »

I rewired it and now the crank to run taper works, it smoothly moves from cranking to running position.

But I can't see why it sohuldn't work with the wiring the other way around too? It would be more failsafe to make sure the crank to run taper time actually works with both setup's?
jsmcortina
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Re: Stepper idle motor and the Crank-to-Run Taper Time

Post by jsmcortina »

The code is designed for more steps = more RPM. The calcs don't work the other way around.

James
I can repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

My Success story: http://www.msextra.com/forums/viewtopic ... 04&t=34277
MSEXTRA documentation at: http://www.msextra.com/doc/index.html
New users, please read the "Forum Help Page".
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