Join Date: Sep 2005
Location: Honolulu, Hawaii
That's pretty strange. A car should only be in open loop until the exhaust / O2 Sensor reaches 600 degress and the PCM is ready, then goes into closed loop. Seems like your O2 sensor is going bad but there are ways to single out the problem. A dirty MAF can cause that problem too. Try getting a MAF cleaner that won't harm electrical components and see if the problem goes away. If there's a large vacuum leak, that could be a problem too. If you have a bottle of propane and a nozzle, hook up your scan tool and watch the trims while tracing the vacuum lines with propane but don't blast propane everywhere. If there is a leak, the trims will change from the gas being sucked in when you apply propane to the area. As for the O2 sensor, there actually is a way to "clean" that sensor. I know this sounds weird, but if you have a blow torch and something to clamp your O2 sensor with, torch the sensor until it's cherry red. The fire will "clean" the debris/carbon on the O2 sensor. Just don't burn the wires connecting the sensor. If you have a DVOM, probe the pins while you torch the sensor, constantly bringing in and out of heat. The numbers should raise and lower as you sweep the torch. Once your DVOM shows 0-900 mV, the O2 sensor is as good as new. If it doesn't, time to replace. Remember, O2 sensors use DC (Direct Current) Don't know if this'll help but it's worth a shot. If you happen to have a fuel presser tester, that would help out too. Test the rails for proper fuel pressure. And check the injectors. If you have a long screwdriver, place the tip of the screwdriver on an injector and the handle to your ear then listen to the clicks (acts as a stethoscope). If one sounds off, that injector may be dying. Should have sharp rhythmic clicks
Last edited by SpunkyB15; Mar 21st, 2013 at 10:05 PM.