[s-cars] help - no boost...

[Theodore Chen]

Figure out if the problem lies with boost control or with boost itself.  I'd start off by disconnecting the N75 valve from the wastegate, leaving the wastegate port at atmospheric.  Plug the N75 port so you don't have an air leak.  This should result in lots of boost.  Be careful when test-driving, because the ECU can't open the wastegate to reduce boost.

You could also try the output test, but even if the N75 passes the output test, it's no guarantee that the N75 is still good.  The output test only actuates it about once per second.  Mine passed the output test, and I wasted a bunch of time testing other stuff before coming back to the N75.  I tested it with a function generator, and it worked fine initially but failed at higher duty cycles.  A new N75 fixed the problem.

By the way, make sure the hoses connected to the N75 aren't kinked or significantly longer than stock.  I had some boost issues when I set up my GT2871 with a new aftermarket MAF to turbo hose (needed because the GT2871's intake is larger than the K24's), which had the connection to the N75 on the front rather than the side of the hose.  I couldn't put the N75 on the front of the hose because the plastic intake snorkely was in the way.  II had to run a connecting hose to the N75 and used a 90 degree plastic hose barb.  The stock setup has the N75 plugged directly into the hose.  I had problems with low boost, which went away after I shortened the hose as much as possible and used a smoothly bent piece of copper tubing to make the turn.




----- Original Message ----
From: james McCarthy <jjssmccarthy at yahoo.com>
To: s-car-list at audifans.com
Sent: Sun, December 27, 2009 8:50:32 PM
Subject: [s-cars] help - no boost...

So replaced the head gasket and placed a New 034 wagner em and oem rs2 turbo - lots of replace hoses... now NO boost.
N75 is plugged in - car runs fine but ZERO boost... thoughts?
What could I have left unconnected or connected incorrectly that would result in zero boost???
thanks
-jamie


      
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