Hi all, I'm new here, I bought a 92 Pintara Executive in January with only 81000 km on the clock. You beauty!
I've looked extensively through these forums and have found the advice very informative. I'm so glad this resource is here. I'm sure I'd be lost without it!
Now, I've had a problem with the car running rich and burning a hole in my pocket. The ECM reported a code 13 (oxygen sensor), so I went ahead and bought a suitable replacement from Repco. This was before I had read extensively through these forums and the UA Corsair fsm. When driving in field service mode, after the car warms up, I'm assuming the mixture ratio feedback from the O2 sensor to be in a closed loop most of the time. Is this correct? Because I'm finding that the ECM light is flashing rapidly (open loop) all of the time except when I'm decelerating, in which case the light stays solidly on, indicating it's now in a closed loop but running rich.
I'm going to test the water temperature sensor tomorrow but I can't see it as being the culprit. If it was reporting the engine temp as under 60 degrees, I'd expect the system to run in open loop all of the time and not going into closed loop every time the car is slowing.
From the fsm.
The mixture ratio feedback sensor does not operate (i.e. open loop) under the following conditions:
when starting the engine
when the exhaust gas is cold
when the engine speed is above 3800 rpm
when the engine speed is below 3800 rpm but the engine load is above a predetermined rate
when engine is idling for more than approx 20 seconds
when throttle position changes faster than a pre-determined rate (i.e. acceleration / deceleration)
The only thing I can see that is consistent with what I'm seeing (closed loop only when decelerating) is that the ECM is receiving feedback that the engine is under too much load, even when idling. It senses the load is acceptable when decelerating because the engine is being pushed along by the car's momentum rather than the engine pulling the car along or simply overcoming frictions from within the engine, from the belts and the torque converter. Does this sound reasonable?
The million dollar question is, how does the ECM know how much load the engine is under? Does it determine it from one or more sensors and which one(s)? I may have to resort to taking the car to an auto electrician if it all becomes to difficult to determine with a multimeter.
Thanks in advance to anyone who responds. Cheers!