Forum > It's all about the Turbo...

Turbo Boost (lose)


The other day I posted a question regarding turbo boost.  I got no replies (no problem) but I did want to follow up. The question regarded my limited boost (10PSI) with  the Premium switch activated on a LA-3 computer.  Ideally I should have been getting 15 PSI.

Anyway, I tested the intercooler and hoses to 15 PSI without leaks.  I tested the wastegate and it was holding back pressure properly.  Eventually I found I had mis-routed a hose and as best I can tell the problem was either one of these two things:
1. The hose routing was really causing boost lose. Or...
2. I was getting 15 PSI boost, but the hose routing caused the gauge to read low.

I had relied on a hose diagram that is readily found on the internet.  In the hopes that no one else has my bad experience I'm linking to a representation of that WRONG diagram. Scroll down to the next post for a representation of a correct diagram.


thats good you finally go it fixed 8)
brad :)

So sould you tell the difference??? Or did I miss the answer?

Sorry about that.

 Ummm..., this gets somewhat complicated. I used a diagram that came up on a Google Image search.  When you click to be taken to the actual location of that image it doesn't appear.  You are taken to a page with another link to the  page . Yet that link comes up as a server error. Thus, no image.  If I just had people do a Google image search (like I did) the placement on Google would change over time based on how Google ranked the image.

I had made mention of this over at NATO and some guy posted the image in his post confirming it had errors.  So, I think, 'great, I'll just link to this NATO post and everyone can see (and confirm) what I'm talking about.' Ahhh..., No.  Unless you are registered at NATO and signed in you won't see the image.

Do, do Do, do - Doooo... I feel like I'm in the Twilight Zone!  For years (and ever a few days ago) I was referencing a hose diagram that had (unknown) errors.  Now when I try and warn people about it no one can see it!!!

OK, I'm going to log in at NATO, download the image and post it here.  The error (for me) was the green line that runs from the intercooler to the vacuum Tree.  That is incorrect. It should run from the intercooler through a number of one way valves and connect to the speed controller on a T/C.  I just eliminated the hose all together.  That is the only change I made and I'm now reading 15 PSI boost. So, either it was dropping boost, or just affecting the the gauge reading to 10 PSI when I did have 15 PSI.

Lastly, it was mentioned that there were other errors so just avoid using that diagram all together.

I can't remember which it was, but there is a vacuum Y fitting either on the 2.3T intercooler or on the compressor housing and one of those is what determines the "premium" boost level.

The 2.3T boost control method is actually a controlled leak in the wastegate line. Leave the controller shut and you have the wastegate's normal boost level of ~10psi. Open the controller and it bleeds off enough air to make the wastegate maintain 15psi instead. The Y fitting acts as the metering orifice. Opening the passages in it will increase the upper boost limit. Since the 2.3T EEC-IV uses vane air metering, the bled-off air has to go back into the metered air stream between the turbo and air meter.


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