XSeries-forum

2005 e53 3.0
Sometimes my turbo dosnt seem to come in, no pattern to it, not down to temperature, i can set off and she runs fine then suddenly shes as flat as a pancake, put your foot down and nothing, its like a loose wire playing up, could it be?

A common cause is failed vacuum hoses. Check all of the vacuum lines are intact and connected. There is also a small ‘reservoir’ on the offside that looks like a gridded plastic bottle with a thin line off each end. The hoses need to be intact there too.

An airflow meter on the way out can cause massive flats spots when pulling away, on earlier m57 engines you can unplug them and if it's then grand you know what the issue is. I can't say if this works on a 2005 model though.
Most issues are in turbo vacuum control of the vanes rather than an actual turbo internal fault and that vac reservoir is prone to cracking too I believe so worth a look.

Its also possible its the boost sensor located at the rear of the intake manifold, secured by a 10mm bolt...you really need diagnostics undertaken or you'll be chucking new parts on which are not required.

Thanks will get it looked at