cutting out at junctions

[T_Pot]

Ive cleaned the stepper (not sure how well, but looks clean)
changed plugs and leads, but occasionally when the clutch is in and revs drop, she cuts out. or even the revs drop as if about too at times


any ideas?

[RedCabbage]

Did you clean the seat in the plenum where the stepper sits?

Alternatively careful use of PTFE could seal up any airleaks down the stepper thread.

Try unclipping the electrical block of the stepper motor while running the engine to see if it gets better or worse.

[T_Pot]

RedCabbage said:

Did you clean the seat in the plenum where the stepper sits?

Alternatively careful use of PTFE could seal up any airleaks down the stepper thread.

Try unclipping the electrical block of the stepper motor while running the engine to see if it gets better or worse.

no i didnt clean the bit the stepper goes into, and i didnt think about an air seal i have to admit.

will try this

do you mean disconnect the stepper then drive it or just have it tick over?

[RedCabbage]

T_Pot said:

RedCabbage said:

Did you clean the seat in the plenum where the stepper sits?

Alternatively careful use of PTFE could seal up any airleaks down the stepper thread.

Try unclipping the electrical block of the stepper motor while running the engine to see if it gets better or worse.

no i didnt clean the bit the stepper goes into, and i didnt think about an air seal i have to admit.

will try this

do you mean disconnect the stepper then drive it or just have it tick over?

No don't drive it. If you can get the car to idle on its own I would try unplugging the electrical block. The engine will probably die but at least you will know the stepper was active.

I have experienced problems when the stepper motor was cleaned but not the seat, shine a torch in there you'll probabably find it is very sooty.

When I had an air leak down the thread it hunted rather than cut out but it is worth removing this from your suspect list.

[thegman]

did it always hunt?

i find it only tends to hunt when very hot?

[blitzracing]

RedCabbage said:

No don't drive it. If you can get the car to idle on its own I would try unplugging the electrical block. The engine will probably die but at least you will know the stepper was active.

If the engines ticking over OK when you disconnect it, it should stay at that RPM, as the stepper will simply stay in its part open position without power. You will have trouble keeping it running when its cold with it disconnected however.

Mark

[Aubrey]

I'd clean the inside of the plenum, see if that helps, worked a treat on mine.

[GreenV8S]

Get the engine up to temperature and idling steadily at the right speed, disconnect the electrical plug from the back of the stepper motor, and take it for a test drive. If you still get the problem, you know it's nothing to do with the stepper motor and associated logic. If the problem goes away when you do this, it could be that the stepper motor is sticking but could also mean the engine is out of tune, as Blitzracing explained a few months ago.

[nicktowe]

This happened to me and it was as simple as ythe airflow meter multiplug having been left undone by numpty mechanic