No throttle - idle sticks at 2000 rpm

[Dartmoor7]

As title, car initially fine but at some point in my regular 35 mile blat the idle starts to stick at 2000 rpm.

Bear in mind that my car is an early 1.4 SS and was fitted from new with the alloy, forward-facing throttle body. The throttle pot or whatever it is on the side of the TB has JZX 2963 marked on it.

Any ideas?

Reset already tried.

[Tony Whitley]

Did you try unplugging the IACV? Though the reset would normally correct that...

[tin duck dave]

Sounds like throttle position sensor to me.

[Stationary M25 Traveller]

Pedal pivot bush sticking ?

 

Disconnect cable from pedal .... see if pedal moves freely. See if cable moves freely through outer cable.

[Dartmoor7]

All mechanical operating elements are fine.

[Fyldeflier 1]

It could be the stepper motor on the right hand side of the throttle body(looking forward from the driving seat)

you should hear it re set when you turn the ignition on or off.

these sometimes get dirty and stick giving the symptoms you describe.

easily cleaned with a cotton bud.

try disconnecting the wiring to it ,go on your usual blat and see if that cures the fault.

If it does thats your problem.

in this warmer weather the car should start ok without it . use a tiny bit of throttle instead.

 

[Dartmoor7]

Thanks for that.

Which bit in this pic do I undo to clean it?

 

 

 

Edited by - Dartmoor7 on 15 Jun 2014 14:19:01

[Fyldeflier 1]

Ok

This is a bit tricky to explain but under the throttle cable quadrant there is a small fitting that rises and falls when driven by the stepper motor.

this is part covered by a small rubber boot to keep muck and water out.

However it does get a bit clogged and it can require cleaning.

you do not have to take anything to bits but it would be easier to get at with the wiring plug removed.

Looking at the picture it seems that the casting the wiring plug attaches to has been damaged and is held together with cable ties. This could be part of the problem and the wiring itself is known to break and cause issues.

[Dartmoor7]

Thanks again.

On mine access to this looks easy.

It is the little post shown here under the idle adjustment screw?

[Allen Payne]

Also worth checking that there's not a air leak anywhere else or the vacuum hose hasn't fallen off

[Fyldeflier 1]

yes thats the one!!

[Dartmoor7]

Fingers crossed, I've done a couple of blats and it seems to be OK.

I cleaned and lubed the stepper motor thing, cleaned the electrical contacts, and cleaned inside the TB.

One of these things has done the trick (famous last words - got a 130 mile cross-Devon round trip tomorrow so we'll see).

Thanks guys.

[Fyldeflier 1]

Excellent ! 😬