high idle?

[jono172sport]

hi all
got a problem.... car has started to idle quite high it fluctuates between 1500rpm and 3000rpm its as if its searching for revs? if you rev it, it revs fine then drops back to 1500rpm then increases and drops in between the 2. had this problem with a previous car ended up beeing the air flow sensor could it be this? any ideas?
any help appreciated
thanks
jono

 

[f0xy]

all vaccum pipes connected?

 

[jono172sport]

yeh they are, sorry to mention its a 2001 172 engine

 

[jono172sport]

any one?

 

[carrmrc96]

only think i can think of is the the vac pipes. I forgot to reconnect one of mine and had the same problems as you. if the vac pipes are connected then make sure there not split somewhere.

 

[f0xy]

or a leaking gasket on either part of the inlet manifold

faulty throttle body could also be the problem

 

[carrmrc96]

take off your elbow, start the car up and see if the butterfly valve is fully shut at idle.

 

[sideways danny]

cable throttle? seen this on a few recently, they dont shut fully unless you snap the throttle on and off again. could try cleaning out the TB thoroughly and then lubricate the spring mechanism. If not, start looking for a good/new one. Worth clenaing out the ICV too

 

[jono172sport]

cable throttle? seen this on a few recently, they dont shut fully unless you snap the throttle on and off again. could try cleaning out the TB thoroughly and then lubricate the spring mechanism. If not, start looking for a good/new one. Worth clenaing out the ICV too

its the newer engine mate with the fly by wire throttle i believe these dont have a icv?