gordkent

I am looking for a bit of advice on the ecm I am working on, 16168625 with memcal BHAZ (1993 Chev half ton 5.7), the problem is the engine has been modified with camshaft, block has been decked and flat top pistons, what is happening now is that once in closed loop at idle the engine will stall out, I set up the idle parameters to 700 with ac on and off and this has helped a lot but once in closed loop will stall sometimes,
I have wideband monitoring and seems like when it stalls it is running quite lean as well above stoic (15.9).
if I unplug o2 sensor to prevent it from going into closed loop the engine does not stall and engine runs nice, much nicer than when in closed loop but the afr is around 11.9 or 12.2, goes up and down a bit.
If there was an easy way to set a parameter to prevent it from closed loop only at idle or any suggestion would be greatly appreciated.

Schurkey

WHY is that thing running lean in closed loop? Is that a defect, or a tuning screw-up?

Get a scan tool connected so you can read the data stream. What is the coolant temp sensor telling the computer? What are the short- and long-term fuel trim numbers at idle? What is the O2 voltage at idle? Can the computer accept a wideband O2 sensor output instead of the OEM sensor? Any EGR at idle? Does the Idle Air Control valve work? How about the TPS voltage?

What is the fuel pressure?

What is the cranking compression of all eight cylinders?