Remember my post about a malfunctioning O2 sensor? Well yesterday I swapped a known good single wire O2s from my 92 Z28 into the 89RSconvtZZ4TPI motor. I really can't remember the exact sequence but before I did the install I checked the wiring path to the ecm. I took and first grounded the O2/ECM wire, 4mv. I then ran 12 volts thru my fingers to the O2/ECM wire, 996mv. With the car running and O2 sensor still not getting hot enough I gave it a quick shot of 12volts and BAM! She started working properly, mv's as high as 780/800 and dropping as low as 4mv when you let off the gas after a quick stab of the throttle.
However if I turn the car off and let is sit, it seems to need the 12 volt shocker to kick start operation. Could this be a faulty O2 sensor ground coming from GE15 on the ecm (tan/wht wire)?
It also seems to function properly as long as the car is sitting at idle. If I start to drive it, the O2 sensor degrades to the 300/400mv range after awhile.

I have found my painless harness does not have a Tan/wht wire, probably tan/black. I am gonna investigate the ecm ground. I did a test of the header, hooked my multimeter up to the back of the alternator and tested for ground on the header. Good ground everywhere, even thru the coating.
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