Clio 172 revving up as you slow down by itself!

[billyclio]

Hi, Hoping someone can help with this sometimes embararassing situation!

Just bought my Clio 172 and when i slow down in traffic it will sometimes rev itself up! I say in traffic because this is the most noticable time, but you can sometimes drive without accelerating as the throttles sticking.

Ive open up the bonnet and the black platic round type thing (sorry for the discription) that the speedo cable is attatched to does seem to be sticking. I say this as you push it back it will return to normal idle. Also if it does happen all you have to do is rev the car up and it will return to normal revs. Ive sprayed it the spring etc with wd40 but still seems to be sticking, even worse in traffic...Does anyone know a way to solve this problem, i would be very greatful!

 

[RichMcc]

Get someone to pump the pedal while you spray it with WD-40,
Take the inlet hose off and spray the inside with carb cleaner there maybe deposits inside causing the butterfly to stick, if its really bad take the throttlebody off.
If its not that look on the plenum where the throttlebody connects to it, at the front there will be a little nipple, this should either have something blocking it or a black hose joining to the fual pressure regulator I think it is, anyway make sure its not just left open.

 

[billyclio]

Just followed you instructions. The butterfly bit seems to be sticking as if its too big for the carb! Any ideas now?

 

[charliezinn]

my chaps old fiesta zetec used have this prob as it turned out to be the actuator (small relay type switch) which was sticking momentarily when pulling up. small part fairly costly from ford(£80) not sure 4 172

 

[Saner]

Have you checked under the accelerator pedal itself? Directly connected to the pedal is the throttle cable which passes through the engine compartment bulkhead, they can (very rarely) wear and fray by rubbing on the edge of the hole in the bulkhead, if it has frayed it can cause the throttle to stick.

 

[billyclio]

But in the throttle body itself you can see amrk where the butterfly seems to be rubing. I'm getting the impresion that its rubbing as it heats up, when the metal expands. Could this be?

 

[Rob669]

Apparently it's a common problem. I've had it twice now (fnar fnar).

The first time it was sorted out by replacing the accelerator cable with a new one (costs about £35, fitted). If your cables old I suggest you do that first.

The problem came back for me after I fitted a modified plenum and therefore I had to take the accelerator cable off. I'm convinced this problem has something to do with how you fit the accelerator cable onto the throttle body (sounds daft though, I know).

I ended up taking the throttle body off and cleaning it with carb cleaner. I also took off the idle control valve and cleaned that with carb cleaner. None of these sorted the problem. I am told that it is caused by a weakness in the throttle body return spring. But I've more or less cured mine now. I just fitted the accelerator cable back on in a way that seems to suit it best (using the adjuster). I got my son to operate the pedal while I squired most of a can of WD40 over the spring. I also lubed the cable where it joins the pedal. Mainly though I drove it at over 130 mph (on a track at the weekend) and it seems completely fine now!

Cheers, Rob669