i recently had my engine coils leads and sparkplugs changed but i have the engine management light come on again it seems the same problems as last time car jumpy and loses speed going up hills the garage says might be fuel injectors on computer it comes up coil four but he says they are ok. could it be the injectors or is it the coil. the car is a ford fiesta zetec 2003 plate.
If you've had the coil pack replaced its unlikely to be that....unplug the connectors to the fuel injectors and measure the resistance of each one. They should all be exactly the same - about 16 ohms.
