Iac

Enhanced parameters are additional data that can be scanned from most late-model GM vehicles. The LS1 and L67/L36 support all of these listed below.

Enhanced GM Parameters: (may not apply to all vehicles)

Parameter	Description	Typical Value
BARO	Barometric pressure	Depends on weather. Typically
		29-30 inches of mercury. NOTE:
		Doesn’t work on all cars
FTC	Fuel trim cell	Varies with engine conditions. In
		general, numbers go up with
		load, except for cells 20-22,
		which may be used for open loop
		(including full throttle)
IAC	Idle air counts	20-60 at warm idle to 100 while
		cruising; higher when a/c is on
IDC1	Injector duty cycle, driver’s	1-2% at idle, up to 85% at full
IDC2	side & passenger side	throttle
IGNV	Ignition volts	12 volts or so with key on, down
		to 9.5-9.8 during starting, then
		13.5-14.5 with engine running
IPW1	Injector pulse width	2-4 milliseconds up to 15-20 at
IPW2		higher rpm’s and full throttle
KR	Knock retard	Zero to 3-4 degrees
		Ideally, should always be zero
MAFF	Mass air flow frequency	2200-2300 at idle, 9000+ at full
		throttle
MISP	Primary misfiring cylinder	1-8 if misfires present
MISR	Revolutions with misfires	0-10 revs is common; more than
		that may indicate problem
TFT	Transmission Fluid	Ambient to 200 deg F or so.
	Temperature	Above 225 and the tranny fluid
		starts to deteriorate.
TPSV	Throttle position sensor	0-5Volts; typically 0.5 volts at
	voltage	idle & 4.5 at full throttle

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