I have just joined here. I have a 320Cd convertible diesel on a 2005 plate, E46. I had recently been experiencing a gradual reduction of power and fuel economy used to get about 50 mpg now getting 36 mpg on the motorway. Any 320 Cd owners out there who can cross compare their MPG?
I noticed that the rev meter when stationary/parked on idle would move noticeably slightly up and down especially when starting in the morning. I also noticed that the mpg display on the dash when driving on the motorway would also waver quite a lot feeling like its hunting. As well as this the mpg meter shows very poor figures for a few seconds even when im braking, it feels like the mpgs drop when for a few seconds when im coming to a stop which is the reverse of what you would expect since my foot is off the gas.
Anyway, I decided to change the air mass meter buying a new original bosch unit, although the rough idling has improved when stationary the power and economy are still the same. I also cleaned out the EGR valve which was pretty dirty, the valve was still pretty hard to move with a screwdriver with some force after cleaning it? is this normal?
Ive ruled out that it cant be the air flow meter, are there any other sensors which could be causing this? How would i go trying to resolve this? I have read somewhere there is a pressure sensor and crank/cam position sensor could this be causing the problems?
Ive also noticed that the external temperature reading on my dash display changed erratically at times like today it was about 10oC outside and the dash was showing -1oC! This temperature moves up and down quite a lot and does not seem accurate. Could this external temperature sensor reading have any effect on the power and fuel economy?
I have no engine management light come on (it did come on when i disconnected the flow meter but switched off itself when i plugged the new one in).
Any ideas to help me check to get my car back to normal?