engine revving on its own??

[JayDot90]

Hi guys just bought a clio a 172 from a mate, everythings sound mechanically and its just passed its MOT but every now and again when idling (ie. traffic lights or junctions) it revs the tits off its self.
I asked the garage to take a look but he forgot . At first i thought it could be throttle body sticking but it happens without me touching the pedal.

anybody got any ideas or had experience with this in before?

Thanks, Jono

 

[scoop172]

Not familiar with clio's yet but sounds like an idle control valve is clogged up. In other makes i would say find it, clean with like a carb or brake cleaner and stick it back in.

 

[JayDot90]

Is that a something and nothing job or am i best getting it into garage?

bit of a noob where engines are concerned lol

 

[scoop172]

Dont know where it is on these cars but if its easy to get to to i would say do it yourself if you have some basic tools.

 

[VXR killer]

unfortunately theres no removeable idle control valve as the throttle body is electronic (not cable) and whole throttle body is a sealed unit. i would suggest taking it to a specialist and getting it on diagnostics. could be a faulty throttle body or faulty pedal at a guese. you can get a second throttle body off ebay from £30-70.

 

[JayDot90]

electronic throttle body makes sense, thanks mate

 

[jon_r]

It is a cable throttle, with an ICV, if it's a phase 1.

 

[JayDot90]

So new ICV first and then if no luck try a new throttle body?

 

[VXR killer]

if yours is a phase one then yes, but it just may want cleaning with carb cleaner as it may be carboned up.

 

[mark smith87]

It's the throttle body sticking. They need a good clean. Mine was doing the same sort of thing.

 

[Ex-User (19928)]

If it goes back down to idle and then back up afterward then it's definitely not a sticking throttle body.

As said, you have a phase 1, the ICV is on the side of the inlet manifold, I would just buy a new one.

 

[mark smith87]

Mine was the throttle body sticking. I had it cleaned and it stopped the idle from revving and dropping all the time. Mine is a phase one as well.

 

[Ex-User (19928)]

That makes little sense with respect. Think about how it works, you come to a stop, the idle settles because the TB is closed (this is at least true for a cable throttle setup). So now the only air getting to the engine is through the ICV. If your TB is sticking then the idle wouldn't go as low as idle.