Stepper

[Kev1976]

Hi all. Still quite new to TVR ownership but I'm having some idling issues. Today I have taken stepper motor out and have connected wiring plug back in. Turned on ignition nothing happens to stepper, turn off ignition and stepper jerks around quickly for coouple of seconds. Is this normal?
Thanks

[ianwayne]

At ignition off, the stepper motor drives all the way inwards ready for next engine start. This is correct.

[FoxTVR430]

Hi Kev1976 welcome to TVR ownship

The Stepper motor will try to control the idle speed, when the engine is running by opening and closing an air bypass valve.
As above every time the engine / ignition is switched off the stepper motor recieves from the ECU an amont of pulses to retract. Sometimes you can hear this as a buzzing sound when you switch off the engine.

There are quiet some post if you search for "stepper motor"
GOOD LUCK

[Kev1976]

Oh ok. I also thought that stepper comes out when ignition turns on. The issue I have is I seem to need throttle when engine kicks in to keep it ticking over until car warms, but the other day for the first time in a year the car cut out when coasting in neutral. Managed to bump it back in but car wasn't very happy for the next 5 mile or so. I'm sure everyone is fed up of stepper motor questions but I'm not really mechanically minded just love the cars

[Hedgehopper]

Kev, I have found that it's just as important to clean the seat as well as the stepper motor itself.

Also, don't use any force when tightening it up because they crack in half very easily!

[J400GED]

When the engine is absolutely cold - i.e. left overnight - unplug the AFM and then start the car. If it starts ok then that will point to a duff AFM. An easy check to carry out. Is your AFM an original Lucas 5AM or has it been replaced?