Good morning everyone. So yesterday I switched the tuning in the car from open loop back to closed loop after making some adjustments. Now before I go crazy here let me give you the low down... The open loop tuning was done with a wide band. Closed loop uses a heated NB for readings. I can view the WB reading in closed loop... so here it goes.

What I am noticing with the car in closed loop now is excessive fuel smell, confirmed by both BLM and the wide band reading. The ECM is commanding so much fuel added that idle is hanging around an 11:1 (.8 lambda) So I checked a few things this morning.

First the sensor wire to ground, I got 5.8Mohm between the connector and ECM so I will say the feed to the ECM is ok but I still need to get the car out of the garage to double check continuity on the wire itself and not to ground.

Second the sensor itself to ground and its wire to ground also check out. No continuity to ground from the wire and the sensor itself grounds to .06 to ground.

Third I confirmed 12v to the heater circuit key on.

Fourth, yesterday in my data stream my O2 voltage was a steady reading. Approximately 70-150 mV and not moving much between the two. This is what also prompted me to check all the above. The tune is a slight modification to a known good one that the NB didn't correct much this time last year. So I am figuring it may be an issue there.

At this point, I am going to assume that the vehicle side checks out and any issue is with the O2 sensor itself? I can see running open loop for a few months fouling up a non heated sensor but I would be surprised with a heated one. But I suppose it is possible. SO basically I believe the NB is toast... Any opinions otherwise?

 

Without seeing all of the data, I would say it's either the sensor, or you have an air leak in the exhaust stream that's diluting the exhaust. Low voltage is either a lean exhaust or a weak sensor.

 

Started it today and it's fine. Go figure. Wonder if probing the plug made contact again. Those pin type connections aren't the best. Oh well. Stupid things I tell you.

 

What brand is the recommended O2 sensor? Bosch or Delphi?

 

What is the difference in the brand of the sensor?

 

Just buy a name brand, and you'll be OK.

 

For the one wire style... I haven't seen it but a few guys more knowledgeable than myself have said the delco is better and that a bosch will do weird things... there isn't much of a price difference between them all so I'd just use the delco. Take that with a grain of salt though. Iirc that came from Bob over at dynamic EFI (the guy who created EBL flash and such)