EvilBevel

Before you ask: yes, I did a search, and read various threads for about 4 hours now, but didn't find a clear answer.

On my current setup, boost sometimes seems to be "stuck", giving only 0.2 bar up to about 4000 RPM, and then going to the normal boost target levels of 1.2 bar with a sudden sweep. I'm pretty sure it is a mechanical problem somewhere.

This is very intermittant: on some days I don't have the problem at all. I was first thinking boost solenoid/oil in pipes etc... but then we should see at least 0.5-isch bar if the solenoid stayed shut.

So I'm down to : sticky waste gate or a dumpvalve that doesn't close up properly (I have the Forge recirculating job). Problem started at the same time the Forge was installed IIRC.

To find out if it is the BOV, I would temporarily like to block (stick something in between ) the path from the intercooler to the BOV. This way, I could check myself if it's the BOV, or if there may be a problem with the wastegate.

Furthermore, I'm considering removing the BOV altogether, and hope the VF23 can stand the friendly abuse for a while

I tried to block off the recirc hose going back to the inlet tract, but that didn't really work, I could still hear the blow-off noises.

Would something like aluminium from a beer can inserted between IC and BOV do the trick, or is that not sturdy enough ?

Can someone help me out here ?

R19KET

Evil,

It would be worth checking the D/V itself. It's easy to remove, and open up. Check the piston for evidence of sticking, or scuffing, and that the "O" rings are greased.

Also check all the hoses associated with the IC, and inlet manifold. A common culprit, is the feed to the brake system (big hose on the inlet manifold, back right).

Lastly, it may be that the actuator has lost it's pre-tension. The TD04 has an adjustable rod (under the heat shield I'm afraid) that connects it to the waste gate. This may need to be shortened slightly.

Mark.

EvilBevel

Thanks for that Mark. I haven't been clear though - I run the VF23. Otherwise I think deleting the dump valve may be a bad idea for the standard TD04L, but I hope the VF23 can cope.

About the preload on the actuator. When I disconnect the solenoid (top connector), I get 0.5 bar boost as expected (unless the problem occurs of course), so it looks like it's behaving normally most of the time (am I right on this one ?). I'll have it checked in a week by the guy that normally works on my car (he's off for a rally).

I'll check out the hose to the brake system. Shame is: it's an intermittant fault, so difficult to trace, that's why I hoped there was an easy way to temporarily remove the DV out of the equition.

I'll open it up and see if my non-tecchie eyes can detect anything. Would it be a good idea to treat it with WD40 ?