Quantum Syncro AWD L5-2226cc 2.22L SOHC (1987)
Engine Control Module: All Technical Service Bulletins
Engine Performance - Erratic Running/Lean Mixture
GROUP
97
NUMBER
87-08 December 21, 1987
MODEL(S):
Jetta, Quantum, all m..y.
SUBJECT:
Erratic running condition/ lean mixture
A lean running condition can be caused by stray voltage affecting the oxygen sensor signal.
To determine if stray voltage is present:
^
Disconnect the oxygen sensor lead (engine off).
^
Turn on the ignition (do not start engine).
^
Measure for voltage between the green lead of the disconnected oxygen sensor and the ground connection at the cold start valve: Voltage
should not be more than .55VDC (residual voltage for electronic circuitry).
If more than .55 volts is present:
^
Clean the grease from the fuel injection control unit plug using rubbing alcohol and allow to air dry.
^
Reconnect the plug to the control unit.
^
Repeat stray voltage test.
