2004 1.8 Turbo ZT, revs bounce on idle

[Lav]

My 2004 1.8 Turbo ZT revs bounce on idle, the car drives fine but when idling, with the air con on or off the revs seems to bounce lower rather than higher?

Ive cleared the plenum drains to no avail.

Any suggestions welcome :lol:

[Phil]

How much do they bounce? My 75 1.8turbo revs probably bounce about say 100 rpm,

[Lav]

has to be a good few couple of hundred rpms, maybe a few hundred.

You can hear it in the standard exhaust too when the revs dips as it pulses.

[Alex30013k]

When its really really cold my 1.8 does that and feels like its going to stall if i tap the gas but then release straight away. - it only does it for the first 4 seconds after starting.

[Lav]

mine would do it after 4 hours of driving :(

[eVoHicks]

Hi,
probably not connected, but my rover coupe used to do this, especially when running alot of electrical stuff. Would stall sometimes when coming to a junction (engaging the clutch).
Andy

[Lav]

any other ideas on this folks?

Picture / Price of an Idle Control Valve and/or coolant temp. sender would be helpful :)

[Lav]

still stumped on this folks :(

suggestions welcome :)

[Christopher]

When my 1.8 did this it turned out to be a dodgy HT lead - once changed it was perfect.

HTH

[T-Cut]

Any suggestions welcome :lol:

Cam belt tension?

TC