Well, We've just about exhausted the possibilities.

Put in a new 4 wire AC Delco O2
Verified that we had good +12 V and good ground to heater wires
Verified that the ECM o2 low pinout was grounded to block
Tied the O2 sensor ground to block ground
Verified pin outs to the O2 hi
Unshrouded the O2 sensor by moving it in closed to the exhaust stream.

Still getting frequent O2 ready bit set low and resulting open loop.
O2 crossovers seem to get slow

Anybody have any other ideas?

Open to any guesses here.

Thanks
Steve

 

Application? car, engine, ecm?

 

Application: 1967 Chevelle
427 Big Block
730 Computer
Single O2 sensor in the Bank 2 exhaust manifold
right where the 3 bolt exhaust pipe flange bolts
on.
The car runs reasonably well and is not throwing any codes. I've got the VE table semi close as far as I can tell. However with the O2 sensor giving me fits, all bets are off there too. Any whoo my BLM's are in the 124 to 134 ranges.

Car will go CL intermittantly then revert back to OL. O2 crossovers seem slugish and O2 ready bit goes low and back to ol we go. If you pedal the throttle it will generate some crossovers and bang back to CL again for a little while.

Hope this helps. I'm really pulling my hair out here. Opps, I don't have any hair!

Thanks
Steve

 

Have you tried using a single wired O2? I read an old post about somebody having problems with a heated O2 and other ecms, the 730 and the 746 ecm if I remember.