[Mk2] [Turbo] Actuator problem?

[Jaspa]

ok, quick short story.

I've just come back from the Rolling Road and have a slight problem.

My boost gauge was only ever showing a peak of 0.8Bar but seemed to pull reasonably so put it down to an iffy MBC (sorry tim )

Anyway got the graph. Down on stock boost and graph is showing a peak @ 0.8bar @32k revs and then dropping by 38k to around 0.6 and slowly dropping to 0.4

Chappies at the RR have suggested it is probably the Actuator. Does this seem a fair guess?

Obviously TVIS is disconnected so will be lower than stock with the MBC disconnected, but doesn't the granger type controllers confuse the actuator (so to speak) to over ride it?

Any other thoughts?

Thanks in advance

Stuart

[Slarty]

Just a thought, but if the actuator fails, you should see higher than normal boost no??

It might be a leak elsewhere in the boost pipe, ie turbo - intercooler or intercooler to throttle body.

hth.

[Jaspa]

No idea, I had a quick look for leaks at the weekend but couldn't find anything obvious.

Any other thoughts?

[Slarty]

Well the job of the actuator is to actuate (surprisingly enough lol) the wastegate. The wastegate then diverts exhaust gases away from the exhaust turbine and a set pressure (what's call stock or actuator pressure). This maintains the boost pressure at a certain/set level.

If you're losing boost, it can't really be the actuator at fault (unless it's stuck open, and in that case it'd just take longer than normal for your boost to come up to pressure) so by that it "has" to be a leak post turbo.

I'd have a good look round for perished/split hoses after the turbo but before the throttle body. If they are ok, it may possibly be in one of the (many) smaller boost carrying pipes (bov etc)

May not have fully answered your question but hopefully it's given you an idea of how things work

[solmansoft]

You may be able to help me here!

I find that my Turbo starts off boosting fine, then sometimes it ends up taking ages for the boost to build.

So if the actuator is sticking, does that mean I'd need to get a replacement or can it be fixed?