Bov Troubleshooting Discovered Boost Controller Issue

[mikel]

My R33 GTST factory BOV started to not fire over a period of several weeks and I got an increasing amount of flutter as the pressure went back into the turbine.

I replaced the BOV with another 2nd hand factory unit, but tested the spring on the old unit and it worked exactly the same as the "new" one, so knew as I was installing it that I was probably wasting my time - and of course the new unit didn't work any better.

I then started checking the vacuum lines which is where I started to discover issues.

I have a HKS boost controller (EVC iv). The instructions off the web say Port 1 connects to the plenum after the throttle body, Port 2 should connect to the turbo output before the intercooler, port 3 connects to the internal wastegate actuator, and port 4 unconnected and blocked off.

On mine the line from port 1 went to the BOV only, with a closed off T that probably should have gone to the plenum.

The factory vacuum line from the plenum was also closed off.

Port 2 is connected the the inlet pipe after the intercooler but before the throttle body (as opposed to the instructions which say it should connect to the turbo outlet before the intercooler).

Port 3 connects to the wastegate actuator as per instructions.

The car was tuned last on the dyno and the shop said the HKS boost controller was working properly (not sure how?) and the current boost is supposedly 1 bar (apexi FC and HKS 2530 turbo)

I disconnected the line from port 1 of the boost controller, closed it off, and connected the vacuum line from the plenum to the BOV - hey presto the BOV works again.

This raised several questions:

1. why would the BOV firing slowly degrade - I've changed nothing since last tune?

2. without port 1 of the boost controller being connected to a decent vacuum signal from the plenum how would it do its job and control boost ?

3. would I have a potentially damaging scenario with the wrong connections (eg too much boost etc)?

4. If I connect port 1 of the boost controller to the plenum as per instructions with a T to the BOV, will that affect the vacuum signal to the boost controller ie should I have a separate vacuum line from the plenum for the BOV?

5. the instructions say port 2 should be connected before the intercooler - currently mine is connected after the intercooler - what difference would this make?

5. if I connect everything to spec will it need another dyno?

I'm planning to put all lines back to where they were following the last tune and take it back to the tuning shop and ask some questions as to why it's set up as it is, but would greatly appreciate your thoughts/opinions.

cheers,

Mike

[DECIM8]

You have raised several good questions .. to which I can only answer .. I have no idea.. sorry dude at least its fixed g.l!