5ktq and Boost isn't everything..turbo, cam, flywheel, 034efi..but still needs help.

[Ben Swann]

FWIW - I did pretty much everything you suggest down below except (3)
bypass the bypass which I just did and came to conclusion that the
brand-new Bosch bypass failed from day 1.

Ben

On Thursday, June 13, 2002 3:04 PM, Bernard Littau
[SMTP:bernardl at acumenassociates.com] wrote:
> [snip]
> > Now the disappointment has been that the engine no longer develops the
> > expected boost.  I played with the schrap.knob and even  resorted to
> > disconnecting any wastegate control whatsoever and the most I
> > have observed
> > is 1.7 bar(~11 PSI) and that is when going full bore over 5k reaching
> > speeds that ask to get thrown in jail fast.
> >
> > Prior to the work, I could easily dial in over 2 bar of boost and had
set
> > to around 15-18 PSI, and reached the set boost around 4k RPM.  A
leaking
> > exhaust manifold(small cracks) and gasket prompted me, or should I say,
> > gave me the excuse to perform this major undertaking.
> >
> [snip]
>
> Hi Ben,
>
> I'm coming in late on this, and have seen that I overlap much with
other's
> comments.  However, you need to make sure the ECU is not a factor.  This
is
> best done by disconnecting the lower waste gate hose.  I assume by your
> comment on removing waste gate control you mean the WGFV hoses.  Did you
> disconnect the lower waste gate hose from the waste gate, and plug it?
>
> If the lower waste gate hose is not connected, there should be no opening
of
> the waste gate, and the turbo should make boost like crazy.  With the
lower
> waste gate hose off, ECU control and WGFV are not a factor. If it does
not
> boost right up to 2.2 bar, then here are some possibilities:
>
> 1) Your measurement device is incorrect.  If you are using the ECU
> transducer, hook up a real pressure gauge to one of the manifold lines
and
> check that it too reads 1.7 bar.
>
> 2) Your waste gate is not shutting completely.  Try pulling a vacuum on
the
> upper chamber of the WG, and release it suddenly.  It should make a clunk
as
> it closes.  See: http://www.sjmautotechnik.com/10vwaste.html under LEAK
TEST
> THE WASTE GATE DIAPHRAGM.
> Your diaphragm should not be an issue, as when it goes, you get lots of
> boost.  Clunk the WG a few times to make sure it is closed, and try the
> boost test again keeping the lower Waste Gate hose off.
>
> 3) Your bypass valve is leaking.  Somewhere I have a picture of my bypass
> valve test fittings :-)  I took a 1" dowel and cut two pieces off.  Use
the
> two pieces to plug the hoses after you have removed the bypass valve.
 Run
> the Boost Test again with the lower Waste Gate hose off.
>
> 4) Your plumbing between the turbo exit and the intake manifold is
leaking.
> This is usually accompanied by some rich running.  Hard to tell normal
rich
> from way rich at high boost :-)  What kind of Intercooler are you
running?
>
> 5) Your turbo is leaking/broken.
>
> 2 & 3 are your most likely cases.  1 & 5 are reaching.  4 is a
> possibility -- I initially had my hoses, from turbo to IM, with the hose
> clamps as tight as I usually make them for the cooling system.  Below 1.5
> bar, this was an adequate tightness.  When I raised the boost, I kept
> blowing hoses until I made the clamps way way tight.  Sometimes the hoses
> blew off completely, sometimes they just vented under higher boost.
>
> Good luck,
>
> Bernard Littau
> Woodinville, WA
> '88 5ktq
>