Technical data of the Digifant system (VW Transporter T4)

Engine letter designation	AAS	AAF
Engine power	84 hp.	110 hp.
Maximum speed	5300 rpm	5500 rpm
Idle speed	800 ±25 rpm	800 ±25 rpm
CO content	0.7 ±0.2 vol.% (up to 5/93) 0.3 ±1.2 vol.% (up to 6/93)	0.7 ±0.2 vol.% (up to 12/92) 0.3 ±1.2 vol.% (up to 1/93)
Idle speed stabilization
Valve resistance	2 – 10 Ohm	2 – 10 Ohm
Control current
Coolant thermostat plug removed	420 + 30 mA constant	420 ±30 mA constant
Coolant thermostat plug is on	420 ±30 mA fluctuates	420 ±30 mA fluctuates
Depending on the load, if electrical consumers are turned on	400 – 1000 mA	400 – 1000mA
Throttle lever idle position	5 – 30	5 – 30° (up to 9/91) 0° (from 10/91)
Throttle lever position at full throttle	not less than 100°	not less than 100° (up to 9/91) not less than 80° (from 10/91)
Fuel pressure regulator
Fuel pressure at idle speed:
- vacuum hose is on	about 2.5 bar excess pressure	about 2.5 bar excess pressure
- vacuum hose removed	about 3.0 bar excess pressure	about 3.0 bar excess pressure
Holding pressure after 10 min	not less than 2.0 bar excess pressure	not less than 2.0 bar excess pressure
Injection valves
Injection jet
Resistance on each valve	Same for all valves	is the same for all valves
Connection resistance for all valves:
– 4 valves in good condition	15 – 20 Ohm	1 5 – 20 Ohm
- 3 valves in good condition	3.7 – 5.0 Ohm	–
- 2 valves in good condition	5.0 – 6.7 Ohm	–
– 1 valve in good condition	7.5 – 10 Ohm	–
– 5 valves in good condition	1 5 – 20 Ohm	3.0 – 4.0 Ohm
LED indicator test
Test conditions: Hall sensor is in good condition, injection valve plug is removed, starter is on	The LEDs are blinking	The LEDs are blinking
Potentiometer CO
Resistance between contacts 1 and 3 Note: The resistance depends on the position of the CO adjustment screw	0 – 2 kOhm (up to 5/93)	0 – 2 kOhm (up to 12/92)
Idle switch
The throttle valve is closed	max 10 Ohm (from 6/93)	max 10 Ohm (from 1/93)
The throttle valve is open	Resistance is endless.	Resistance is endless.
Throttle damper
Gaps
- verification	1.5 – 2.5 mm (up to 5/93)	1.5 – 2.5 mm (up to 12/92)
- adjustment	2.0 mm (up to 5/93)	2.0 mm (up to 12/92)

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The text has been checked: Orlov Dmitry

Previous articles
Checking the intake air heating
Temperature sensor resistance value
Idling switch
Checking injection valves
Injection valves — removal and installation
Throttle body Shock Absorber

Next articles
Diagnostics of faults of the fuel injection system Digifant

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