Stepper Motor Tutorial???

[ElvisWedgely]

Can anyone explain to me what the stepper motor does exactly and how it does it.

I already know that it is a form of choke mechanism that extends and retracts, commanded by the ecu, but how does it create the choke effect for the engine?
Why is it connected to the plenum by a rubber hose? as well as having electrical connections?

The reason why I ask is because on my 3.9 hotwire this mechanism is totally disconnected. The wires are all connected up to the stepper motor in the usual way but the rubber hose has been removed and both ends bunged up. The car starts up fine first time and drives perfectly, the only drawback being that it takes time for it to idle smoothly until the engine warms up. That aside, everything is fine and I was wondering if it's worth reinstating?

Tony. TCB.

[blaze_away]

Try this, very good source of enlightenment on all things RV8

http://www.rv8r.co.uk/tickover.html

[Wedg1e]

It is actuated by the ECU to admit extra air as necessary to maintain the correct fuelling for idle - that's why it's called an Idle Stabilisaton Valve. Most modern cars use them, which explains why most cars (or vans) will merrily pull away and let you go up through the gears without using the throttle. Try it on the flapper V8 and you'll probably stall

[ElvisWedgely]

blaze_away said:

Try this, very good source of enlightenment on all things RV8

http://www.rv8r.co.uk/tickover.html

Thanks for this thread. It really explains the stepper motor in detail and has answered all my questions in one.

Tony. TCB.

[adam quantrill]

What - even the age-old question: "How's the Wedge treating you?"

[Jack Valiant]

All been said in the RV8R link which is an excellent reference, I used some of it for the Gredge conversion. I have found that regular cleaning of the stepper motor is essential for good reliable and quick returns to idle, here is mine for those not seen them:



Chris