What would cause...

[shabs]

what would cause the car to rev at 1200 rpm at start and then after a minute or so go back to normal rpm like 750-800.

is it normal?

[Sam]

Dirty throttle body?

Have you got the choke pulled out still <big grin>

[Lex Luthor]

what would cause the car to rev at 1200 rpm at start and then after a minute or so go back to normal rpm like 750-800.

is it normal?

Classic duff CTS.
Reported once a week on these forums.

[shabs]

choke?

dunno, its a petrol!

[shabs]

Classic duff CTS.
Reported once a week on these forums.

whats that?

[nickynibbles]

What your experiencing is basically an automatic choke system. If your too young to know what a choke is, basically until not that long ago you'd have a lovely little lever that opened a butterfly or flap in the engine to allow a richer fuel/air mix, and basically increasing the idle speed. This was to allow the engine to run better whilst warming up, and you simply shut the flap once you'd set off or the engine was warmer, and so returning the idle speed to normal. Nowadays its all automatic and perfectly normal. Ironically enough modern sports bikes for all their 160+ mph capability still have a manual choke?!

[shabs]

cheers mate. nice one

[RickT]

Petrol engine..

More than likley it could be a split vacum hose which is casuing a drop, so the auto choke is bouncing the revs up to keep the car running..

i had it on mine..

Get your head under the bonnet and listen for escaping air..

if not this..

then a dodgy coil pack which has a slight misfire.. which is casuing the choke to kick in..


if you require for info please post.

RickT

[Sam]

Classic duff CTS.
Reported once a week on these forums.

coolant temp sensor?