engine revving when starting engine

[juany]

Hi everyone here is a strange problem and any help would be very much appreciated. i have been driving this car for ages with no problems at all and parked up and switched off the engine and got a coffee and when i went to start the car it just turned over like there was no petrol but a 1/4 tank of petrol was showing, so i called the breakdown and a mechanic came out and tried starting the car with no avail then he changed the fuel pump fuse to see if that was the problem then the car started BUT when it started it went into full rev mode like the accelerator pedal was pushed down after a while the mechanic said it seems the throttle body has jammed. I called my mechanic and he has looked at my car yesterday and said the throttle body was working but seems that the auto choke solenoid was stuck open so i managed to get another solenoid and fitted and the same thing happened just went into high rev mode. The mechanic then plugged his computer into the car and did a full diagnostic's and no fault came up no error codes nothing everything showed normal even when the engine rev fully the computer showed no faults.

 

any ideas on this please

1.6 16v petrol 2002 focus hatchback

many thanks

  

[juany]

Someone has said about clearing the ecu by either taking out a fuse or disconnecting the negative battery terminal for a few hours 

Any suggestions 

Many thanks

[Dan62]

Check the pipes around the inlet manifold, one has been knocked off or it has split.
For the engine to rev you have air entering the manifold other than through the throttle body or IACV.

This engine has a mechanical throttle body so resetting the ECU is not relevant.

Good luck.

[Marineboy]

Good call Dan.  I had a bike that was doing this, letting air in on the vacum side of the carb years ago.

[juany]

Someone has said about clearing the ecu by either taking out a fuse or disconnecting the negative battery terminal for a few hours 

Any suggestions 

Many thanks

 

I've checked all the pipes and connectors and all good, replaced the throttle body and the car is still doing the same on full rev and plugged my diagnostic computer and nothing is showing a fault and no engine management is showing, 

 

[Dan62]

Not sure then. The Fiesta has a pipe behind the manifold attached to the engine and that then connects to the lower left hand side of the inlet manifold.
This pipe eventually splits and causes what you describe. Not sure the Focus uses the same arrangement but again you must have a vacuum leak for the engine to have high rpm.

[juany]

I have replaced all the pipes around the engine and same as before the engine revs high and again I've connected a diagnostic's machine and no error showing and I've spoken to 2 ford engineers and they cannot tell me what's the problem as they have no idea