Reduced boost from 4000rpm when hot

[i-wonder]

Hi,

This is my first post so apologies for getting anything 'wrong'... My MY2007 Turbo has done 55k miles and is standard other than a BMC panel air filter. Recently I'm noticing a distinct loss of power from around 4k rpm once the engine is good and hot (typically after 50 miles+). Running in sport (overboost), the boost gauge shows the normal 1 bar (ish) up to around 4k then it drops off to about 0.6bar rather than staying at 0.9-1.1. Much the same happens if I run in normal mode (although no overboost obviously).

When the car has been parked up for an hour or 2 the problem doesnt immediately return, it takes 20-30 miles. All is fine below 4k rpm

Local OPC has recently replaced 1 actuator (car is under warranty) as a result of the usual failed actuator symptoms (i.e. boost all over the place at all revs) and the car was great afterwards for about 3k miles. Plugs are close to their 40k replacement and being done shortly but the car isnt misfiring.

OPC cannot find anything wrong, no fault codes. Of course when I took it in the issue didnt present itself because the car was parked up for 30 mins before they could run it...

Has anyone had a similar experience and can give me any tips as to what to get looked at?

Thanks.

Steve.

[s4quatt]

This sounds to me like heat soak.

How warm is it outside?

[therock88]

I would get those plugs changed and see if ir does not smooth out. As they age and when you get in that boost, strange things happen...Similar to what you describe...

Also as mentioned above, when it gets hot out, not the Turbo's best friend. Engine DME starts doing some things to the engine as it heats up and you may experience simiar issues.

Good luck.

DC

[V.D]

Had a similar problem w my 2009 turbo, changed the spark plugs and the problems gone.. But i'd recommend getting some performance spark plugs like i did (in order to build a basis for future performance upgrades, which eventually many of us do:) )