[s-cars] Fw: Hoppen Stage IV - boost (or lack thereof) issue

[QSHIPQ at aol.com]

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I'm with the broken turbo.  This is NOT a motronic problem AT ALL.  If the
hoses are intact, then ck the turbo.  Remember, when motronic fails
(specifically the WGFV stays open all the time) baseline spring pressure
prevails (about ..3bar pressure - 1.3absolute).  Ck for codes, no codes?
Broken turbo.  IME with broken turbos, sometimes if the shaft breaks in the
center, it will still spin freely, and can pass the radial play test, btdt.
The first ck is to go maximum radial play while turning the cold side.
Scraping?  Also ck for aluminum (grey gunk) in the turbo outlet hose (this is
the aluminum shavings from the cold side).  Failing all that You may need to
pull the downpipe out a bit to see of both sides of the turbo spin together.

Ripped wastegates tend to whistle as the hi pressure air exits the WG cap
fitting, and with a turbo this big, you'd still have boost, just not a lot of
it.

HTH
SJ
In a message dated 9/15/02 8:28:46 AM Central Daylight Time,
rpastore at animalfeeds.com writes:


First step, pull codes -- they don't lie.  No codes?  Then check for
mechanical damage to the turbo.

Remove the hose from the maf to the turbo, and spin the turbo shaft by hand
and feel for excessive bearing play.  The shaft should turn easily, and a
only small amount of play is acceptable in the shaft bearing.

If this is ok, then remove the cover from your wastegate.  Move the top of
the valve up and down and make sure the diaphragm isn't torn.

Once you rule out a mechanical problem with these two, we are back into a
problem with Motronic control of the boost.