Ive got a ford mondeo 53 reg 130bhp tdci. It wont start of its own accord, it needs a very quick sniff of ether to get going. Once running its fine, injectors and pump have been stripped and tested twice to find all is well. Its had different rail sensors etc but all the same. Can anyone confirm which sensor is required for the initial starting, crank or cam?

Also the ambient temp sensor is misreading reads 49C at 19C but pretty certain this wont affect start up as its not the intake air temp sensor, which reads correctly and is part of the AFM.