Temp related low boost

[SuffolkD@aol.com]

Makes sense Taka,  Alt sensor:  thin lower boost to keep from overspinning 
the turbo..................Good point.
Makes me think my alt sensor is fine..................
-Scott by BOSTON 

> From: Taka Mizutani <>
> Tom:
> I experienced pretty much the exact same issue, with similar results-
> I don't know if your car is chipped or not, but anyway....
> With Lehmann stage I chipset, I would normally see 17psi with 19psi
> on 4th and 5th gear extended pulls. When I had an issue, I would see
> full boost until the engine was warmed up, then I would see a peak of
> 12psi with a very slow increase in boost to even achieve the 12psi.
> I replaced the MTFS, the ECU temp sensor on the back of the head, the
> plugs, plug wires, distributor cap and rotor, still no success. Finally, I 
> found
> out from my mechanic that the altitude sensor had failed- I don't really 
> understand
> how this failure seemed to correlate with temperature of the engine, but it 
> did.
> After replacing the altitude sensor, I never saw the problem recur. It's a 
> rather odd
> thing, never documented by SJM Autotechnik, or in the Bentley, but that 
> worked for
> me. I would go through the usual checks (VAG-COM is very useful to see what 
> your
> ECU values are cold and hot) in the Bentley before doing this.
>