(Fwd) RE: Erratic Manifold Pressure: Please help

[quk@isham-research.demon.co.uk (Phil Payne)]

In message <199805140642.CAA07166@coimbra.ans.net> "Renier Meyer" writes:

> To make sure that I was looking at the actual manifold pressure and
> not being fooled around by the WGFV, I disconnected the WGFV and
> bypassed the function.
>
> The boost is controlled by two valves and the WG is set to open at
> 2.0 bar. The erratic manifold pressure starts happening from 1.2 -
> 1.4 bar.

Very small tear in the turbo -> intercooler hose or the intercooler ->
throttle body hose.  Only opens under pressure, but is small enough to
be overcome by sheer flow.  If it's right at the end of one of the metal
fittings, engine sway relative to the chassis will open and close it
too.

One of the less likely alternatives is a loose impellor nut.  Therefore
the first recommendation - pull the hose from the turbo to the
intercooler.  Check for hose integrity, the presence of a retaining
nut on the turbo, and metal splinters in the hose.  Wear an old shirt -
there's sometimes a _lot_ of oil in there.

Pulling this hose is one of the first things to do in cases like this.
Not because the problem is common - but it's easy to do, and the
downside of turbo impellor destruction is metal filings going up the
inlet manifold.

--
 Phil Payne
 Phone: 0385 302803   Fax: 01536 723021
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