Is their any reason to have manual stepper control?

Thinking like this:

Engine is setup to run the following items:

PTO winch that runs best at 1200rpm
Engine driven Endless Air with auto control
Very very low gearing meaning crawling at idle is an option
Hydraulical steering (or hydraulically assisted PAS box)

So you are pootling along in low first- get a bit stuck and want to winch out. Flick the manual stepper control and it raises the rpm to 1200 or so so that you have enough power to run all the engine driven stuff without any problems.

This would mean that you could crawl along without stalling- something that i find pretty dangerous at times. How would having the stepper motor on affect engine performance considering that i will be using a MAP sensor in the Megasquirt unit- therefore the stepper unit will only raise engine speed yes?

How would you actually control the stepper motot? do you supply either 12v or no volts and therefore it is totally open or totally closed- is this right?

MS can control stepper motors, they require a sequence of pulses to step them round one step at a time (as the name suggests ) so no you can't just connect it to +12v.

Maplins sell stepper driver kits for a few quid, or you could perhaps add a switch to the MegaSquirt that makes it step up the RPM's automatically. If there's not code to do it already I'm sure you can persuade someone to write it.

Easier option is fit a second on/off idle valve from another motor that lets more air in.

Check MSEFI.com for stepper driver info.

Dont think that will work, as when you open the second valve and the revs increase, the MS (or other controller) will close the original valve to bring the revs down to idle again.

If you cant find a sofware option in the MS, then you could do something that opens the throttle a tad, perhaps a cable control in the same way a manual choke works...
In fact is there a hand throttle kit for the Defender as there was for the series models...?

How about a bit of hose conected to the plenum chamber with the other end in the cab. Put a tap on that end and as if by magic, you can control the idle speed with the tap.

Si

James,

I can't help thinking with all your plans, if your engine stalls(gets wet) your totally fupped

Hoss - wrong I'm afraid. The MS will only use the stepper motor for raising the revs when the engine is cold, as soon as it's warmed up it closes the valve based on values you input to the warmup table. This is not closed-loop so there will be no interaction between the two as you suggest.

They may have written closed-loop idle stabilisation code for the MS by now, but as with anything in MS you can turn it off as required.

yeah that was a worry too les.

i have got round "i think" with the winch thing as i am going to install an electric pas motor which can be used in emergencies- as it is significantly more efficient than an electric setup i should only need one battery if i ever need to use it!

other than that i am following nige's route with waterproofind the engine using Megasquirt. We will see if it works- if not then i'm following nick with the diseasal route- although i would be very unhappy if i had to do that.

mmmm diesel

Ive got a variable baseline tickover actuator, works in either step mode or infinately variable, sits on the dash and uses negligable power to operate, and its totally waterproof

is it a small sprite?

nah - bicycle gear selector with a cable

i quite like that idea


might have to "borrow" it. I would never have thought of something that mechanical and simple- would have ended up with something very pretty and posh, but which didn't work very well!

just fit a choke cable onto the throttle butterfly arm.

pull, twist, lock. done.

Popular with Jeep owners I understand. They mount them on the gearstick as the foot throttle can be a little difficult.

Chris