TD4 Freebie self revving

[tdi130dualcab]

Hi,

My folks have a TD4 Freebie that starts revving by itself at idle.

The revs will go up to 2500 rpm and move about around there.

If you put your feet on both the brake and clutch, the revs go down to normal idle (has to be both, not either all). Take one or both feet off and it starts again.

It does not happen all the time, but frequently (at least daily).

It happens both with a hot and cold motor.

Any one else had anything like this? and any pointers???

Cheers...

[101RRS]

Does the check engine light come on? If the ECU detects a fault it can increase revs at idle to compensate.

If the check engine light does not come on then the ECU is not detecting a fault so it thinks that things are normal so I would be looking at the throttle sensor attached the accelerator pedal as it may be sending a high reading to the ECU. Applying the brakes and clutch sends a signal to the ECU that the car is going to slow and cuts back fuelling.

Garry

[inside]

I have had a similar problem on my other car but not sure if it applies here. It maybe a leak on the inlet manifold or somewhere between that and the airfilter. This may also explain why it stops when you use the brake as it runs on manifold vacuum. But then I'm just guessing.

[PhilipA]

TD4 =Diesel= no manifold vacuum.
Speed is controlled by injector pump/ECU.
I do not know throttle linkage arrangement but assume fly by wire.
Is the stepper motor that drives the pump OK?
There are usually 2 senders at the throttle pedal end.

I really suggest getting error codes read as first action.
Regards Philip A

[tdi130dualcab]

Thanks for the replies.

I took it for drive yesterday, and when the high rev at idle is happening, when you are driving at 40-80 k's there are momentry losses in power and the engine light flashes on.
The engine light does not come on when it is high idling.

I guess I'll have to get them to go to the steeler to get the error codes read.

Thanks.................