[Gmecm] Vortec L31 oscillating at idle

[Jake Tucker]

	Well, we're finally getting close to having a vortec injection
transplant running in an '84 Suburban.  We started with a fresh 350 with
vortec heads, and installed a vortec injection setup out of a '97 onto the
motor to replace the TBI system that had been running the motor.  There were
a few setbacks along the way, but now the motor is running and appears to
need just a little tuning.  The main problem now is that it is hunting at
idle.  Engine speed oscillates from 300 to 1000 RPM's for several seconds
before the engine dies.  This is especially a problem when it is cold, and
the engine won't stay running at all without opening the throttle a little.
In general, the engine runs, but doesn't give the power we'd expect at this
point.  It is a '75 block that was rebuilt with Vortec heads.  To do the
vortec conversion, all the sensors, intake, distributer, crank sensor,
harmonic balancer, and accessories were transplanted from a '97 vortec motor
with a cracked block.
	Any ideas what would cause the oscillating problem?  I would like to
watch the IAC motor counts, but I can't seem to find that data on the
software I'm running.  Right now, I'm using car-code 2 which is sold at
www.obd-2.com.  I also have the OBDII tuner by tunercat.  He has since sold
his design to Jet performance.

Jake