|87-88 4.1L VIN 7 MFI
||Oxygen sensor voltage stays between 0.35 and 0.55 volts for 60 seconds
during closed loop operation after the engine had been running for 2 minutes
and the throttle angle was above 4%.
||Coolant temperature sensor signal indicates a temperature of over 275°
F for 3 seconds.
||Coolant temperature sensor signal indicates a temperature colder than
-47° F for 20 seconds.
||TPS voltage was above 4.3 volts for 10 seconds when the MAP sensor signal
showed manifold vacuum above 15 pounds, or TPS signal voltage was over 4.5
||TPS voltage was under 0.25 volts for 3 seconds when the engine was running.
||Manifold air temperature sensor signal showed an air temperature of -31°
F for 4 seconds after the engine has been running for 8 minutes.
||When engine speed was between 1400 and 3600 RPM and throttle angle was
less than 2%, the MAP sensor signal showed low voltage (High manifold vacuum)
for at least 5 seconds.
||Manifold air temperature sensor signal showed an air temperature over
293° F for more than 3 seconds after the engine has been running for 4 minutes
and a vehicle speed was present.
||EGR open command did not change the fuel mixture when the command was
given during off-idle operation.
||MAP sensor signal was too high (low vacuum) for 2 seconds when throttle
angle was less than 2%.
||MAP sensor signal was too low (high vacuum) when engine speed was less
than 600 RPM, or MAP sensor signal was too low (high vacuum) when throttle
angle was over 20%.
||Engine idle speed was either below or above desired speed by 300 RPM for
||Faulty or incorrect MEM-CAL.
||The EST signal did not change when the ECM applied bypass voltage to the
||Knock sensor voltage was either above 3.5 volts or below 1.5 volts for
||Oxygen sensor voltage was under 0.2 volts for 60 seconds of closed loop
||Oxygen sensor voltage was over 0.7 volts for 30 seconds in a closed loop
when throttle angle was between 3% and 45% and engine had been running for
at least 1 minute.
||Charging system voltage was greater than 17.1 volts for 2 seconds. Repair
||Fuel pump signal voltage was less than 2 volts for 1.5 seconds.