MY turbo stops providing boost to my FL2

[jscuz80]

So i've had my FL2 for a year now and I love the car with one exception, when the engine heat get to about half way on the needle the turbo just cuts off and provides no boost, so if im out and about and I need to accelerate from say a round about, I get semi trailer levels of power, I first noticed it after I took it up the beach and after used a underbody wash that blasted the undercarrige with streams of torrential water, after that I had no turbo at all untill a few hours later I drove again and it was back. I have found that while driving if i turn the heater on full and blast full while driving till the engine heat lowers the turbo comes back on again, but this is AUS, I cant drive with the heater on in the middle of summer. is this an issue or just a LR feature, its sort of annoying especially when i need that little bit of extra power and its giving me simple dirty diesel power.
thanks in advance for any input

[theelms66]

Smoke test the intake system.

[woko]

Test the operation of the cooling fans

[jscuz80]

Test the operation of the cooling fans
yeah i did that drove it to work and back, without heater on, left it running for 10 mins in driveway and the fans never came on, but the heat gauge stayed at about 4/10ths and didn't move up the whole time. where as normal driving would see the gauge hit 5/10ths and that's where the turbo would stop working. someone else said the fuel filter if not an LR one can cause issues.