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The mkiv Supra Owners Club

Boost Again!


Tricky-Ricky

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Nope, even after highlighting your stuff in red I still can't work out what pipe was on what :)

 

As I read it, I think the boost source pipe is going to the wastegate actuator as normal. The other pipe from the wastegate actuator that originally went to the wastegate VSV had been extended and put directly onto the EGBV actuator in place of the one that went to the EGBV VSV. The pipe from the boost source that splits to the pressure tank and the EGBV actuator is in place as normal.

 

OK, I'm going to put forward my theory! :) I think your car is one of the supras that for a seemingly unknown reason doesn't overboost when decatted, either that or the restrictor ring is an incorrect size. My car has a 1.25bar restrictor ring but I only makes 0.9bar without input from an EBC. The reason you get 1.2bar with the mod you've done could potentially be due to a leak around the pressure tank area. This could be effectively working as a bleed valve in the hose running from the boost source to the EGBV actuator line.

 

I'd get the EGBV out of the circuit completely. Leave the IACV and EGCV wired open, block off the boost feed that feeds the pressure tank and the EGBV actuator, leave the boost feed that supplies the wastegate actuator connected and block the pipe leading from the wastegate actuator to the wastegate VSV. This completely removes the IACV/EGCV/EGBV, all the corresponding VSVs and the pressure tank from the system. If you still only get 0.8bar, remove the restrictor ring and see what happens. :)

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As I read it, I think the boost source pipe is going to the wastegate actuator as normal. The other pipe from the wastegate actuator that originally went to the wastegate VSV had been extended and put directly onto the EGBV actuator in place of the one that went to the EGBV VSV. The pipe from the boost source that splits to the pressure tank and the EGBV actuator is in place as normal.

 

That doesn't make much sense to me, the pipe from the wastegate actuator to the wastegate VSV is small and a bastard to get to, why on earth extend it all the way out of that area and across the top of the two turbos to the left of turbo #2 where the EGBV VSV is located?! That's crazy anyway as the EGBV actuator sees the same pressure reference as the wastegate anyway, I'm not sure what that setup would acheive?!

 

-Ian

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quote "I'm not sure what that setup would achieve?!"

1.2 bar LOL;)

 

The pipe in question doesn't need to be extended as there is the metal pipe that goes from the waste gate VSV to the EBV VSV,

and now that i have got to grips with just how the EGBV works, your right there was no need for it,

 

Steve i think you could be right about the restrictor ring, but not about the pressure tank, as when i first tried the TTTC mod it was using the swap pipe method, and the actuators where holding open the next day after a drive so no leaks,

 

As for your last suggestion, i'm pretty sure i would get 1,2 bar, but wouldn't taking the EGBV out of the system, be the same as i had it, as it would only have an impact on boost signal if it got high enough to open the actuator?

 

I think i am tempted to put it all back to sequential mode and take out the restrictor ring, and take it from there.

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Tricky-Ricky,

 

I had mine fully decatted with RSR exhaust and with the 'standard' 1.2Bar restrictor ring I only got 0.9-1.0 Bar. Spent ages trying to see why I wasn't getting 1.2 Bar and eventually took the ring out and added 6mm to the diameter (3 mm all the way round). Hit 1.2 Bar nicely after that. They're all slightly different and not all overboost madly, as Steviekid said...

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