Volvo Maintenance Hints for 7xx/9xx - Bill Garland's Nuclear ...

of if it stays above .2 volts, give it the 3,000 rpm treatment and try again.
● If no improvement, then the sensor should be replaced.
Test dynamic performance as follows:
● Reconnect the sensor lead and tap your meter into the signal wire
● Set the mixture to specification.
● Run the engine at 1500 rpm.
● You should see rapidly changing readings that average somewhere around .5 volt as the
computer keeps adjusting the blend. The sensor output should fluctuate around .5 volts.
If it doesn't, replace the sensor. Deciding whether or not response is slow enough to
justify replacement requires some judgment. A common rule of thumb for minimum
activity is eight trips across the rich/lean line in ten seconds, and sometimes you can find
specs for cross-counts.
Regina Diagnostics: [Bruce Young] The above apply, but know that:
● The white and red wires in one connector are the heater circuit; the black wire in second
connector is the signal.
● Red is +12V; white is ground
● Black (connected w/engine running) should cycle rapidly between 0.1V and 1.2V
● Black (disconnected w/engine running) should "after a while" rise to 1.2V
● Replacement is NGK 25002, not a "generic" sensor.
For more information, see the FAQ Engine Sensor section on Oxygen Sensors.
Air Mass Meter Diagnosis.
Setting Base Idle and Mixture on Bosch LH2.2 Cars. See the FAQ section above for tips on
base specifications.
Simple Functional Diagnosis of AMM. [Editor] The classic test of AMM failure is to disconnect it;
if the car runs better, then the AMM is at fault. But here are the OEM tests per the OEM manual
for Bosch 2.4 (the-016 AMM):
1. Check the ground point of the AMM:
● ignition off; disconnect AMM
● connect ohmmeter between ground and terminal 1
● should be 0 ohms
● if not 0 ohms, check the ground point on the intake manifold
2. Check signal from AMM: