what now?

[wbaxter90]

span out in 1st and hit limiter, quickly changed up, seemed fine then got stuck in traffic, and with the clutch down it revs its self to 4500 then back down, over and over.
pulled in at tesco, got out the car and it was revving itself with no one in it!?
got it home, disconnected battery let it cool down, started it up and idled ok, tapped the accelerator a tiny bit and the revs shoot up to redline on there own and you have to quickly pull the key out to stop it.
so what now? idle valve?

[hayesey]

possibly an air leak somewhere? Check all the pipework in the engine bay

[wbaxter90]

ok will do, didnt realize a leak would make it do that!? when you say piping, do you mean boost pipes etc? or just everything?

[hayesey]

esp the pipes to the aux air valve I guess. An air leak below the throttle plate will make it idle high yeah, bigger leak, higher the idle.

[wbaxter90]

checked all the pipes i could see, had the boost pipe off, and tightened all the intercooler pipes, still the same, idles high and tap the accelerator and the revs shoot up quickly and you have to quickly pull the key out. do you have a pic of the pipes i need to check?

[hayesey]

no but they are under the inlet manifold, one goes from the top boost pipe to the aux air valve and then the other comes from the other end of the aux air valve to the bottom of the inlet manifold.  These pipes are about half an inch outside diameter.  It's not going to be the big boost pipes as they are on top of the throttle plate, a leak in one of those would cause a boost leak but shouldn't affect idle speed.

[wbaxter90]

orite ok, il have a closer look, i take it these are very hard to get to?

[wbaxter90]

had a good look and they seem fine? what else could it be?

[PeteG40]

inlet manifold or t/b gasket

[wbaxter90]

what are broken? what do you mean?

[vwmk3jon]

I've had this before. Ended up being one of the small White pipes popping off. Simple as.

Sorry I can't be more precise but was a loooooong time ago.

[wbaxter90]

white pipes? please please please can some one get me a pic or something, the cars for sale and then this happens, so really need to get this fixed

[scotsjohn]

Boost return jammed closed maybe?

[hardchargin40]

Boost return jammed closed maybe?

seen that before.

Although a jammed boost return valve wouldn't allow the car to rev up and down, only up.

Wayne, remove your boost return pipe and boost pipe and check your throttle body, even as far as removing it anyway and check for correct operation.  Possible your linkage for boost return aswell? 


Does sound like a vacuum leak.  Possible a split in your ISV valve/inlet manifold pipe underneath perhaps, ISV trying to overcompensate?  Or as pete has said, TB/manifold gasket.  Check white tube aswell from brake servo one way valve and correctly connected to your ECU, with no damage (ive seen one chaffed once, where someone incorrectly routed it).  How are your brakes btw?  I.E. one way vavle not knackered.  You can get a spray to check for vac leaks, goes purple or something.

[newt]

you would need asevere leak for it to rev that hgh, its not going to be just a small pipe or gasket, id be checking lnkage on throttle etc, or cable,
to check for leaks get your self an aerosol of "carb cleaner" and spray around all joins / pipe fittings BELOW throttle butterfly, if the engine note changes this is where the air leak is
just cant see it reving that high from an air leak, doesnt make sense, even if you take off completely the isv pipe to manifold it wouldnt rev to redline