EFI questions

[dzorde]

Hi everyone,

Been a while since I've had any questions so here goes.  Finally got around
to fitting an O2 sensor to my car (can say that on avgas it still works
after 20+ hrs of operation).  This car has a Wolf 3D running the engine
using MAP, TPS and associated temp sensors.   

Anyway my car has always been running with bright white tail pipes, hence I
figured it was lean.  With the O2 I have found something I can't explain.
The O2 is always around 0.82V going to 0.9V+ when accelerating (seems very
rich), however car runs beautifully. If you lean of the fuel maps to reduce
the O2 readings the car just won't run, seems like complete fuel starvation
as soon as you touch the accelerator (even tried hardwiring the heated O2
shell to the -ve battery terminal to ensure the voltage wasn't floating or
anything stupid).  Why can the car only run when rich (had it on a real gas
analyser and it said very rich as well) ?  Is it the high compression 12.8:1
(or so) ?

Another question, because the system is speed density, when you back of the
accelerator the engine unloads and picks fuel delivery for its new suited
map point (lower load range) causing the O2 to read almost 0V (very lean).
Is this normal for a speed density system ?  It seems correct to me as the
injection is based on looking up a base value in the map, but it doesn't
seem very healthy for the engine to lean of everytime you back of.  I have
been thinking this could be why I have white tailpipes as the car is
spending most of its time on and off the gas when racing.

Lots of questions, but this one has me puzzled.

rgds

Dan     dzorde at soanar.com.au