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EGT Turbo Gauges,

In message <349B523C.7F32@sprintmail.com> Mike Zamikhovsky writes:

> The sad point in EGT setup for our beloved cars is that the data that we 
> get is only academic. We can't easely readjust our fule and ignition 
> systemst to compensate for lean mixture. Yes some of us modify and 
> upgrade fule destributors and wormup regulators but we still don't get 
> accurate performance. I once saw 10V Turbo using MB 8 cylinder fule 
> destributor. It ran rich at idle. There is no win with CIS. Installing it 
> and learning to interprite info is good experence.

The main problem is a lack of understanding of how the ECU intervenes _all_ the 
time.  All of its interventions are against a background of basic assumptions 
about the engine design to which it was originally matched - change the cam or 
gas-flow the head and you _MUST_ change the ECU.  Unfortunately, most (if not 
all) of the 'chippers' restrict themselves to changing boost and timing tables, 
and one or two on this list have shown that this is not enough.  Some of the 
ECU's actions (especially but not only fuel frequency valve operations) are the 
result of complex (hundreds of lines of code) calculations in the ECU using all 
sorts of inputs - even including battery voltage.

On a modern-ish engine (MAC11B and later) there is almost nothing you can do 
that will not unbalance the engine in some way.  Even raising the boost level 
by zapping the tables will almost certainly cause the engine to run lean at 
high boost because of mechanical limits in the air mass sensor.

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