Re: picked up the UrQ, couple things wrong...

[Orin Eman <orin@wolfenet.com>]

> hey all, i just picked up the UrQ from 2bennett...there are 2 things 
> wrong which i notice...

> 1.  Boost cuts out above about 4000-5000 RPM...It has the 1.95 bar chip 
> and wastegate spring, and the stock boost guage.  The boost seems to drop 
> from the 1.8 bar to 1.0-1.1 bar.  Keep in mind this is an 86 MC engine.  

You'll have to define this better... but, if it's not a fuel pump
cutout which is very sudden, the computer _CANNOT_ do this.
At most, the computer can drop boost to 0.1 or 0.2 bar below
that which the spring sets.

> Andrew bennett's theory is that the knock sensor is retarding the timing 
> because of bad gas, which is probably likely as the car has been sitting 
> for months now, and i dont know if the PO had put in supreme.  in 4th, 
> the boost cuts out, at full throttle around 4200and in 5th it will 
> usually last all the way through to 5000-5200rpm.  Its really frustrating 
> when this happens.  Does this sound familiar to anyone?  BTW, there are 
> no vacuum leaks, the car stalls as soon as the oil filler cap is 
> removed....

The knock sensor can make it feel like you slowed down, but again,
even if it goes to the regular fuel map and hits max retard, it
can still only drop the boost 0.2 bar or so below the spring.

Even with a stock spring, if boost drops below 1.3 bar, there
is something mechanical wrong...  Usually it's a split in the
Michelin man hose (the oil filler cap test won't reveal a split here),
or a loose hose clamp, but...

Gary Erickson had a similar problem.  Except he didn't only lose
boost, he went into vacuum!  It turned out that the airbox to
turbo hose was collapsing.  Yes, there is a slight vacuum in this
hose which gets greater the more air that gets sucked in by the
turbo.  There is a reason the factory used metal pipe and thick
rubber hoses on the MC...  If you have that orange spiral reinforced
hose, it _will_ collapse in that particular application as Gary
found out.

Orin.