Rover75 CDTi variable boost
 

Good Day Everyone,

My 75 diesel boost is not stable. Sometimes I have a lot of power and sometimes I lack of boost. I already changed: O-rings, PCV filter, all other filter, new oil. I already removed the MAF sensor plug, but there was no change.
What I noticed so far: When I start the car in the morning the engine is running well, and have a lot of boost. When It's start to warm up I lost most of the boost. When the engine is on temperature I have all the boost over 2.2-3k, but there is only a little below 2k(around 1.8k), but here is the catch. When I stop so the car is in idle and I press the pedal I have boost again from low rev to high rev. even the wheels spin out. Also my UBP is kinda loud compared to my friend MG ZT diesel. If It's the ITP what type is in my car? It's the 5D330678

Thanks,
Devcore

Are you talking about boost or power ?

Sorry about that. I have boost over 2k most of the time, and I don't have power under 2k(so it rev up but no significant change in speed), but when I stay in idle for 10-30 sec, I'm get a huge amount of boost/power from idle to 3k. It's pull so hard even the wheel is spinning(notice it never did before, the car got on speed slowly).

fuel pump may be the culprit...

Thank you everyone for the help. Can be. I'm at 1/4 of fuel right now and it struggled. Tomorrow I will fill up almost full and if it's change than it's fuel pump. Notice: Today the under bonnet pump was silent. I will do the listening test today.

Just to close this topic. Today I filled up my tank and also do the listening test. It's fuel pump. Thank You everyone for the help :)