I have been trying to resolve a stalling/cutting-out problem on a P. reg MK4 Fiesta, 1.3 (EFI engine).
So far I've replaced (with new parts) the air flow meter and the air mass control sensor, which all seemed to resolve the problem for a while- but within a week or so of fitting these, the same problem re-occurs. It has a tendency to simply cut out at low speed (crawling along in traffic, or slowing down at approach to a junction)..and has a hesitance to 'pull' at speeds between 50 to 60 (as accelerating from third to fourth). So far the Ford dealer has not been able to find any fault on the diagnostic m/c. I'm toying with the idea of replacing the throttle position sensor, but have had info that it could be a speed sensor on the gear box at fault! Anyone out there got any sound advice? (other than getting rid of the car).
thanks

MC

Mike Croll, September 2008

Hi Mike, you might of already done this, but I would check all the vacuum pipes that connect to the inlet manifold for any holes/splits listen for a hissing with the engine running, try flexing the pipes, there is also a vacuum pipe that runs from the top of the bulkhead to near the petrol tank where the carbon cannistor is fitted, it might also be worth taking the idle control valve off and cleaning it with "spray carb" cleaner don't use anthing like WD40 as the oil in it will gumm the valve up even quicker, the throttle position sensor can be tested on the diagnostic reader (it does on mine!) nige110162@hotmail.co.uk

nigel, September 2008