Wastegate control valve

[Vulcan Grey]

Looks like the correct Metri-pack 150 type to me.

 

SEALED METRI-PACK 150 SERIES CONNECTORS AND LOCKS Two-Way

WHITE PRODUCTS P/N		OEM P/N	DESCRIPTION
A	F150SS-2	12052641	Female Connector Assembly
B	150TPA-2	12052634	TPA Lock
C	M150SS-2	12162000	Male Connector Assembly

[Gjk]

Thanks for that Travis, you’ve put my mind at rest! I notice from your photo that you have a small piece of foam on the bottom of the solenoid, I also have that on my replacement part. Am I correct in thinking that is the “bleed” port?

grahame.

[Vulcan Grey]

Yes, that is the bleed to atmosphere

[Giniw]

On 03/07/2018 at 12:33, Escape said:

Yes, the wastegate control is only there to allow a higher boost when conditions allow. It does so by allowing part of the boost pressure to escape to atmosphere before reaching the mechanical wastegate.

Isn't it the other way round? To my understanding it's the wastegate capsule side which is vented to atmosphere, and the hose on the pressurised side of the turbo is kept air tight. It would a very bad idea to let the pressure escape.

The wastegate is normally closed, and it will open when the turbo achieves 0.65 bar of boost, because the pressure capsule is calibrated to move at that pressure. And to reach a higher boost pressure the ECU is preventing the pressurised air to reach the pressure capsule by closing the pipe and venting to atmosphere the capsule side.

Anyway, I may have understand either what you wrote or the workshop manual. But I think what I am writing makes more sense than letting the boost pressure escape to atmosphere?

[TAR]

I'll start by saying I haven't read the whole of this thread...

Under normal cirumstances (on any turbocharged car) the wastegate is mechanically operated when the boost pressure reaches a designated figure. As it's mechanical it will always open at the set pressure thus releasing any excess boost pressure to atmosphere. 

If you want to overcome the (default) wastegate pressure and achieve higher boost, you need to bleed some of the pressure seen by the wastegate so it doesn't open. This is done using the solenoid which sits before the wastegate. The ECU will read the pressure presented to the solenoid and depending on the programming, it will bleed some of the boost pressure to atmosphere allowing the rest to go on to the wastegate. The car is now effectively running higher boost pressure and the wastegate is still shut.

The solenoid is built to fail safe in that it is normally closed to atmosphere so the wastegate will always see all the boost pressure. Operation of the solenoid will open it.

I hope this makes sense.  

[Giniw]

OK thank you, I though the solenoid was isolating the wastegate side so that the boost pressure would not reach it.
That now makes sense as a fail-safe that the solenoid is actually maintaining a sub 0.65 bar boost at the wastegate capsule. It's a bit of a pity to let that precious boost escape and the turbo spin faster but I do understand it's nice as a fail safe indeed.

Thank you very much for the clarification!

[Escape]

Gini, you are right and my wording was not accurate. Sorry.

The solenoid does not vent the boost coming directly from the turbo, but the pressure in the line to the wastegate actuator, while the feed from the turbo is closed off. Because the solenoid is switched on and off rapidly (PWM), the result is lower pressure reaching the wastegate. So some boost is in effect bled off, but it's only a tiny volume, from the short pipe between solenoid and wastegate. Not enough to effect the turbo, but sufficient to keep the wastegate closed despite higher pressure.

The diagram from the manual paints a good picture.

Filip

 

wastegate.pdf

[sailorbob]

12 hours ago, TAR said:

Under normal cirumstances (on any turbocharged car) the wastegate is mechanically operated when the boost pressure reaches a designated figure. As it's mechanical it will always open at the set pressure thus releasing any excess boost pressure to atmosphere.

For clarity, the wastegate does not release or vent boost pressure to atmosphere, it allows the exhaust gases to bypass the turbine blades which in turn slows the turbocharger down and it is this which reduces the boost pressure.

[cammmy]

I'm currently trying to diagnose an overboost issue. Gjk, did you ever confirm whether the 214-474 worked? I use an aftermarket ECU that has a 3A circuit for boost control, so lower resistance shouldn't be an issue for me.