[Jagbuff]

Quick background, I have been working on building a more track focused 09 JCW based on a GP2 “clone” that I bought last year. The car has been great, but I felt that a little more horsepower wouldn’t hurt especially for my local track (COTA). I recently picked up another 09 JCW (non-running) at auction that happened to have few extra goodies including a much larger turbo (60mm impeller), larger intercooler and 3” downpipe. Initially I thought this was a very aggressive set up but decided to switch things out (before spending more money on a FrankenTurbo) and look at tuning it if it was drivable. Since the turbo wasn’t new, I replaced the bearings, tested the wastegaste, and added a new Forge diverter valve.

I completed the switch over (Turbo, IC, exhaust) and the car fired right up without any alarming noise. Took it for a spin and immediately sensed that something wasn’t right since the car had no power and quickly went in limp mode. Popped the hood and noticed that the wastegate wasn’t closing so I went though the vacuum hoses looking for a potential problem, everything looked ok. I jumped the vacuum pump to the wastegate actuator and it immediately closed…so moved on to the wastegate controller. Even though I was dubious it was the problem, I replaced it as I had a spare and the cleared faults. No change, wastegate still doesn’t close.

I am not sure what my next steps should be, I have tested the vacuum hoses, they look fresh (not collapsing), tested the vacuum diaphragm of the wastegate, everything open and closes as it should, vacuum pump works, no leaks….

At idle I can see a small pulsation of the wastegate actuator – very little or no vaccum at the hose…but does feels like it is pulsing.

Considering that my car was running fine before the switch out I am confident the problem is related to the turbo and wondering whether this the ECU driven situation which is seeing something outside of expected and keeping the wastegate open? Could a larger turbo create such condition? I do plan to take to car to the dyno but really don't want to waste the time if the turbo set up is way out of spec for an engine of this displacement.

 

[Astroboy]

The wastegate should be closed by default, it should only open when you hit your desired boost level. The preload of the spring in the actuator canister keeps it shut (or should).

 

[Wild thing]

What astroboy said, also try running a standard diverter valve for testing purposes to see what happens.

 

[Jagbuff]

Yes, I am aware that by default when the engine is running and the vacuum pump is operating properly, the wastegate should be closed (but is opened when the engine is not running). At start up, it closes if the system is in good condition - ie good vacuum pump, hoses, vacuum reservoir, and wastergate actuator. Therein my issue, everything appears to be tip top but the actuator appears to be venting to atmospheric so the wastegate is not closing and the care is not making boost. Trying to understand to logic - is it a closed loop at idle that would keep it open if the expected Manifold pressure is greater than 14.7psia? NB; I am not talking about the BOV/Diverter valve solenoid which is always closed unless actuated by ECU (I started with the stock diverter valve and had the same issue).

 

[Astroboy]

I must be missing something. Does the R56 turbo wastegate work differently to every other turbo i've ever heard of or seen? The wastegate is normally held closed by spring pressure and a positive boost source acts on the actuator can to open the wastegate against that spring pressure. Electronic boost control bleeds off some of this boost source signal to give boost above what normal spring pressure would be capable of

 

[Potpot79]

Spring pressure in actuator will open the wastegate when engine is off. Once started the engine vacuum will pull the wastegate closed until you equal the spring pressure with boost from the engine. Then with spring pressure and boost will open the wastegate.

 

[Potpot79]

Is it the same wastegate you are using or one from the new turbo?

 

[Jagbuff]

New turbo, however: the wastegate closes fine when I apply vacuum.

 

[Phil_McCrackin]

I must be missing something. Does the R56 turbo wastegate work differently to every other turbo i've ever heard of or seen?

Yes, it works off vacuum rather than pressure

 

[Astroboy]

Yes, it works off vacuum rather than pressure

Get it binned and fit a proper one

 

[Jagbuff]

Trying to avoid that..."proper one" probably wouldn't work

 

[Tigger2011]

Trying to avoid that..."proper one" probably wouldn't work

Remove the upper heatshield. Measure the distance from where the wastegate actuator mounts to the center of the pivot arm. It should be approximately six inches. Apply a hand vacuum pump to the wastegate actuator. Travel from fully open to fully closed should be approx 13mm. Wastegate should be fully closed at 9 to 10 inHg.