I've recently bought a my99 uk turbo, and i'm having a slight problem with the boost. Occassionaly on the motorway, i stick my foot down and the turbo pressure surges. It goes upto around 1 bar, then goes down to 0.5 bar, does this a few times and then settles in and sticks to just under 1 bar.

Its normally fine around town, but i noticed tonight that it occasionaly wont go above 0.5 bar

Anyone got any ideas on what might be causing this and how to hopefully fix it?

 

I'm new to this subrau lark myself but i had the same problem you are describing. I was going on a long motorway journey so i topped the oil up and must have overfilled it. What i found the problem to be was a small brass restrictor in one of the rubber pipes coming off the turbo had become clogged with oil, i think this stopped the wastegate from detecting the correct boost level so it didn't open and let the turbo create loads of boost until the fuel cut kicked in. I pulled the pipe off with restrictor in, cleaned it out and it cured the problem.

 

I'll be checking the oil level before i go out in it next then!

Cheers for the info, i'll give it a try and hopefully be sorted