MB engine overboost.

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

In message <199801011957.OAA00524@urq.East.Sun.COM> Robert Houk - SMCC WorkGroup Server Firmware writes:

> Ah yes, the most fun kind of problem, the intermittent one!

Hmm.

> Are all of the problems in the warm-up period? (I still suspect the
> ECU; but I can't imagine it disabling the boost check when cold; if
> anything it should run *underboosted* when cold)

They were, until Joe Lowe reported it happening recently on long runs.  On 
mine, the danger point was when the coolant temperature display was on the 
segment below "N".  My car always runs solidly on the "N", only popping above 
it occasionally if I get forced to slow dramatically after a high-speed run.

> Experiment: What is the "failure" mode of disconnecting [unplugging
> the wires to] the WGFV -- does the boost run uncontrolled (overboost),
> or do you get minimal boost? If the disconnect behaviour is to run
> overboost, then this nicely tallies with the observation that the
> problem tends to go away when you start poking and proding, looking
> for it -- flaky connector in the cable makes erratic contact. Very
> typical Audi!

Don't know - waiting for access to Joe's car.

> I fully sympathize with how many weeks it can take to finally capture
> an instrumented sample of an intermittent problem ("fond" memories of
> weeks driving around with the passenger seat full of meters alligator-
> clipped into the dashboard...).

Yeah.  We may just have to leave some of the gear hooked up for a while.

-- 
 Phil Payne
 Committee Member, UK Audi [ur-]quattro Owners Club