Hi Guys
I have a 2002 406 hdi with siemens fuel system which is starting & running but seems to misfire and hesitate and is underpowered.Have had the car on diagnostics which showed a faulty MAP air sensor (now replaced, new) but is still the same.
There is some air in the fuel pipe from the fuel filter to the injector pump which seems to be worse after revving
it as the throttle is released.I heard the hdi is self bleeding but should there be any air in the pipe at all?

Grateful for your ideas!

dgfazer1000, April 2009

Thanks for your advice,will check it out at the weekend.

dgfazer1000, April 2009

id be looking at solenoid valves which are connected to the vacuum side of turbo. left hand side of engine near bulkhead. small black valves with vac pipes attached. lots of problems with these. if air is excessive in fuel try looking at all fuel pipes on engine and also under rear seat on top of fuel tank. sometimes they rub and let air in or connectors wear and let air in.

me, April 2009