Cold start idle issue

[RS555]

Hi, have a MK6.5 Fiesta 1.25 and have had an idle issue with it for some time (last 2 years). When it is started from cold and the automatic choke comes on it sometimes randomly drops idle speed (usually within the first minute of starting) considerably to around 400 rpm then will return to normal but will only ever do this the once and not every time. It seems to do it more during cold damp weather but will never stall and always correct itself. This issue will also show itself if you start up and immediately drive off by the engine becoming rough and unresponsive. Has anyone heard of this one before?

[Tdci-Peter]

On 17/09/2016 at 8:19 PM, RS555 said:

MK6.5 Fiesta 1.25 and have had an idle issue with it for some time (last 2 years). When it is started from cold and the automatic choke comes on it sometimes randomly drops idle speed (usually within the first minute of starting) considerably to around 400 rpm

These engines usually have an electric motor operated throttle body. So there is no choke or idle valve, it is all controlled via the one valve.

Once plugs & leads are eliminated, this unit is usually the next suspect. It can be the valve, the motor, or the position feedback sensors, all part of the throttle body, or the wiring or connectors to this unit.