Weak wastegate/actuator symptoms

[merc85]

Ok various issues wiv the t5 , checked pritty much everything, Coming to the conclusion the actuator is getting weak.

But is the usual Symptoms of this?

intial High boost then a decrease?

Or just not reaching desired boost at all?

Intitial Over boost then followed by a stable boost alot lower?

What are the symptoms?

Best ways to test for a weak wastegate?

Any info much apreciated

[jardon]

When mine was knackered it wouldn't hold boost or reach target. I added 5 turns of pretension and it held fine for about a year then the same problem returned so I fitted a Forge one. To diagnose I would inspect visually and use a pump to see what pressure the actuator just starts to move at - should be 4-5 psi. What I actually did was just add a turn of pre-tension to see what happended when I drove it - more chance of bent rods so your risk there. What is your boost doing - we need that profile if we are going to help properly. If your 15g is peaking at 1 bar+ it will drop off naturally as revs rise ie: A 15g/downpipe/cat back and decent map will hold 1.3 bar to ~4400rpm, 1.2 bar to ~4600rpm, 1.1 bar to ~5000rpm and 1.0 bar to ~5300 rpm. A 16t will hold a little longer but only ~100-200 rpm.

[M-R-P]

It's also worth checking the w/g spindle that goes through the exhaust housing. If it's sticking, you'll get initial overboost then a sudden drop in boost as the pressure builds in the actuator. The spindle can also stick in one place (usually part open) you can test that with a pump - if the actuator backs away from the rod rather than the rod moving away from the actuator, that's a stuck w/g and can be cured with a load of plusgas and a small hammer.