Extremely rich idle

[3400-95-Modified]

Coolant temp sensor? Make sure its sending the right signal to the ECM, if the dash is right that doesn't mean the sensor next too the cooling neck is right.

[weba]

My daily 92 3.1 MPFI (stock) just bumped the emission test second time.

Just installed brand new cat converter on it, plugs and wires are 2 years old and in good shape.

It runs extremely rich at idle, everything else on the emission test passes with glory and with really good values, it just runs rich until gas pedal is touched. I can actually smell the fuel if standing still.


ALDL reader shows that o2 voltage jumps around crazy from 50 to 800mV all the time. BLM is 118 and INT 125. This is at 850-900rpm idle speed (it's COLD outside)


Are we looking at O2 sensor issue here or what? I have quite a hurry to get this fixed before it turns expensive because off the laws here.

Ideas appreciated.