Low Idle

Good morning all,

Bit at a loss here. I noticed my engine was revving low and when downshifting and clutch engaged, revs drop below 500 and the egine cuts out. Anyone experienced this?

I adjusted the idle screw which aleviated the problem, but then after a few days the idle would drop again and the engine cutting out would rear it's ugly head again!

Would anyone know what would cause the idle to drop, even after th adjustment? I've been advised instead of adjusting the idle screw, to adjust the throttle cable bolt to lock the throttle slighlty more open.

Thoughts?

(1989 MK1 GTI Cabriolet)

What would I do, adjust the throttle stop first, back off the screw, put a piece of paper in the gap and do the screw up until it just grabs it, do it up another half turn and lock it off.

Put a new 'O' ring on the idle adjuster and take it from there.

The stop is supposed to be to stop the butterfly hitting and wearing a dent in the throttle body, set at the factory. Not to adjust idle.

As above set it so its closed but not touching the sides of the throttle body and adjust idle using the screw and adjusting the mixture.

As per 'cedar', the first thing i would check is the 'O' ring on the idle screw, and any other vacuum lines for leaks.

vagdream said

As per 'cedar', the first thing i would check is the 'O' ring on the idle screw, and any other vacuum lines for leaks.

X2

Does sound like a vacuum leak somewhere. How does it run when you start it from cold?

Source for the idle adjustment o-ring - https://www.ebay.co.uk/itm/292537424199?var=591890553237