Funky Boost Curve

[robboxr6t]

they told me they replaced the actuator, they didnt say anything about the solenoid.

I went to them because I was under the impression they were the best at it and they know the xr6t back to front. obvoiusly something is wrong if I have all of these mods and this problem?

[rob82]

I would say they have replaced the solenoid and not the actuator....

The wastegate is held shut by a spring, when the correct boost is achieved the solenoid opens allowing a vacuum to pull the actuator open which then pulls the wastegate open, The vacuum is drawn from the intake side of the compressor.

If the spring on the wastegate is cactus it will not remain closed even if the solenoid is shut..

<{POST_SNAPBACK}>

Close. Your right in saying that the wastegate is held shut by a spring however a vacumm reference is applyed to the top of the actuator in order to over come the cracking pressure of the wastegate spring. So in order for an 8Psi actuator to open and vent exhaust gas there must be at least 8psi of boost pressure on the top side of the acuator.

Now when you want to increase boost over the acuator pressure you must bleed the vacumm/boost signal to the top of the actuator. For example if you bleed 4psi from the vacumm/boost signal you now have 8+4=12psi of boost pressure. Remember this only applies to internally gated turbo's.

The boost control solenoid is able to bleed a certain amount depending upon its duty cycle and operating frequency and this is how the factory ECU controls boost.

This all said, I havn't come across one BA actuator that has failed.

[Adam]

The clicking solenoid issue should be long gone on an edited car. A new version of the software was released that fixed this problem, regardless it didn't produce a boost curve like that.

I'd say your problem is tuner related, stock actuator can hold more boost than that.

[Adam]

Elaborating I would say that's its going in and out of closed loop boost control, they probably have set the open/closed loop bounds large enough or not tuned the desired table correctly.

Who are you?

You must have something to do with the industry.

[robboxr6t]

what should I be expecting to run with my mods in regards to boost and power.

thanks heaps for everyones help

[rob82]

what should I be expecting to run with my mods in regards to boost and power.

thanks heaps for everyones help

<{POST_SNAPBACK}>

It should run around 280rwkw consistent with your mods at around 12pound if tuned properly.

[Romulus]

Elaborating I would say that's its going in and out of closed loop boost control, they probably have set the open/closed loop bounds large enough or not tuned the desired table correctly.

<{POST_SNAPBACK}>

I'd say you are on the money there.

[rob82]

Elaborating I would say that's its going in and out of closed loop boost control, they probably have set the open/closed loop bounds large enough or not tuned the desired table correctly.

Who are you?

You must have something to do with the industry.

<{POST_SNAPBACK}>

I work as an engineering programmer at Chiptorque on the Gold Coast.

[Adam]

Good stuff Rob!

I look forward to reading all the helpful info you have to offer us.

[Blonk]

Elaborating I would say that's its going in and out of closed loop boost control, they probably have set the open/closed loop bounds large enough or not tuned the desired table correctly.

Who are you?

You must have something to do with the industry.

I work as an engineering programmer at Chiptorque on the Gold Coast.

Well Rob if you are an engineering programmer, then you would know the force that pulls on the diaphram / actuator open, is not called boost but vacuum and is not neccesarily 8 psi.

Actually negative 8 psi would not even go close to opening the wastegate.

Also the solenoid has no logic, it is open or closed, simple.

I have heard of several faulty wastegates / actuators ...

I had the problem on my T.....

Replacing the actuator or wastegate is a major job not a 5 minute fix either....