weird idle..

[karlktm]

just been to test drive another 172, and it idles a little weird.

when started cold or warm it sits at about 1000/1100 rpm, but when you are coming to a stop the idle goes up to 200rpm and sits ther until you blip the throttle. what could be causing this?
the temp gauge sits on the dot below halfway all the time.. and the car is a ph1 172

 

[karlktm]

anyone

 

[b33fy172]

Sounds like it needs a new throttle cable. Mine does this and i've ordered a new cable costs about £20.

 

[markblack172]

could be the idle air valve
or sticking throttle body

 

[Spongebob 172]

mine does the same and ive been told its the throttle body that needs a good clean...gonna get it done this weekend

 

[karlktm]

how do you clean the throttle body? and pics would help..im a tad retrdent when it comes to that sort of thing

 

[sideways danny]

could well be the idle control valve being a bit sticky.

 

[ForceIndia]

Whereabouts is the idle control valve? Mine started doing this.

 

[ForceIndia]

Anybody?

 

[Fred@BTM]

have a look at the throttle body/round the back there

 

[Chrisjk]

Bolted to the back of the plenum, top right at the back.

 

[ForceIndia]

Cheers Hamburglar.

 

[Fred@BTM]

danke

 

[ForceIndia]

You motherfucka!!!!!!!!

 

[ijaen]

Just follow the main air duct from the filter to the throttle body, you will see a small hose attached to it that goes to a small electric motor with a connector on the top, that's the idle speed control valve, it only has a couple screws, detach it from its mountings and give it a good clean with carburettor cleaner...you should also clean the throttle body, specially around the flap...to prevent it from sticking...

 

[Jamesstone]

My old PH1 track cars throttle body after 90,000 miles


Before :

After :

Idle was all over the place, Cruise control didnt help either ( old dried throttle cable :rasp: )

Once it was all cleaned up & the new cable installed the idle was spot on!

When you remvoe the body you will need a new gasket as its not like the PH2's that have a re-usable rubber one