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Check oxygen sensor for lean condition... Posted by walt [Email] ![]() ![]() In Reply to: Runs Hot: Any *positive* test for water pump pressure?, tEd:P, Sat, 16 Apr 2011 13:40:06 Members do not see ads below this line. - Help Keep This Site Online - Signup |
If you have an analog needle type voltmeter with a 1 volt full scale setting, lean condition can be checked by looking at voltage from green wire from engine computer while it is connected to black Oxygen sensor wire. Reading close to zero volts indicates a lean condition. This test works when the engine has warmed up enough for oxygen sensor to output a voltage and for fueling to go into closed loop mode. If sensor is cold or bad, engine computer will ignore it and run using other inputs. Good warm sensor will oscillate around 0.5 volts. Some causes of a lean condition can be a distributor rotor that has blown out its internal 1 kohm resistor, plugged fuel injectors, un-metered air (vacuum leaks), bad ignition timing, or a bad air mass meter. If you think impeller is loose on water pump shaft, you can remove big radiator return hose from rear of pump and see if you can turn impeller. Sometimes water pump doesn't turn because outer part of harmonic balancer pulley on crankshaft is slipping. This usually makes a squealing noise right after starting engine and can cause low charging voltage, since alternator is driven by same belts as water pump and alternator. If you mark the outer A/C pulley against the double waterpump/alternator pulley using whiteout correction fluid or white grease pen and the marks move, the double pulley is slipping.
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