[801coppertop]

911sc 1982 - CIS + Lamda
Recently Rebuilt - JE 9.8 compression, headers, 2in 2 out GT3 muffler; everything else stock

WUR pn - 090 Fuel Distributor pn 0 438 100 077
Vacuum test results - No leaks
Compression all w/in 3psi
WUR & AAV voltage correct - Both working as expected with about 3-4 minutes to heat bi-metalic strip
Decel Valve - Performed TSB and closed by 1mm
Fuel pump volume- Over spec
System Pressure - 4.9
Control Pressure Cold - 2bar - (@17.2c)
Control Pressure Warm - 3.5bar
Pressure after 20 mins - 1.9bar
Air Sensor Plate set at .5m below venuri line
All injectors have great spray pattern and are injecting within 5% volume of each other

Lambda System -
W 15 deg grounded - 65 Duty Cycle
Lean stop 02 Grounded - 90 Duty Cycle
Rich stop - 13.4 Duty Cycle
35 deg grounded - enrichment occurs for 2 seconds to 75 Duty cycle for 2 seconds
New O2 sensor verified working and in spec; even have tried to use my MTX-AL wideband as a narrowband emulator and had more or less same results
Lambda system seems to functioning as it should.

Ignition -
MSD with MSD blaster coil - Clewett Engineering 8mm wires - New Cap & Rotor - New Bosche Trigger wire (Wired correctly, verified by Oscilloscope)

AFR set to 14.3-14.4ish while


Here is the issue as best as I can define/pinpoint it.
Engine runs well as it is warming up. Even into closed loop (a bit of oscillating idle but runs ok)
Once engine is fully warm/heat soaked engine runs lean, starts to backfire a bit off idle.
Runs well at speed and under load, with the occasional stumble.
The main lean off idle has been happening in varying degrees since I can remember. It seemed to get worse after a recent rain storm where
fuel went very lean (o2 sensor had taken water in) I was able to drive home in Open loop with o2 sensor unplugged. Recently the car has driven its best
with the o2 sensor unplugged and a bit rich.

Need some CIS wizards advice, to this point I have studied and read many of the available books on the subject, including
Porsche Fuel injection manual; Probst - Fuel injection and Engine Management: Watson - How to tune & modify Bosch fuel injection - and many many many responses to others CIS woes...
Im having a hard time seeing what has changed to make the engine running characteristics different once fully warm.
Control pressure stays the same - No leaks (Even smoke tested while hot) - Lambda seems to be functioning as it should..; the level of patience I have for continuing to mess with CIS is dawning.