oldandintheway

"Something might be keeping the stoichiometry,14.7 to 1 off. Might be EGR or Evap. Possibly the MAP sensor, or a small leak somewhere. Could also be dirty injectors. Might want to obtain your fuel pressure readings too."

But I should still see the activity of the sensors on the scan tool..correct? They are just stuck at 0.445 V. (Ive gone through 2 sets of new sensors, same ).

oilcanhenry

Yes you should. I am starting to think it's possible that your ECM is malfunctioning.

oldandintheway

Yup...me too...I broke down and ordered one yesterday, went out today,..it will be here by friday.. I will probably just wait until then and swap it out (its coming preprogrammed) before going back and revisiting all the measurements. From all the forum discussions and my own research..I only now feel that I sort of understand the O2 sensor system..so it will be alot easier for me to recheck things. I also ordered an O2 sensor extension cable which i will butcher to allow me easy access to line data 9so I dont have to back probe) so I can check directly the sensor output really easily.

I also went through wiring diagrams in detail so feel much better about that as well. I found where the relevant grounds are:
G101 and G119 for Battery, right front wheel house and right front of engine, respectively
G105 and G117 for Block, braided lines, right rear of engine compartment and right rear of engine, respectively
G119 - O2 sensor heater circuits right front of engine, Fig 52 Ground Distribution, Pg104,
G120 - PCM right top of cylinder head, Fig 36 Engine Performance,Pg 72, or G131 - PCM near thermostat housing, Fig 52 Ground Distribution, Pg 104 (there seems to be a discrepancy in the diagrams for the PCM C3 pins 17/18 ground pins from the document I consulted, unfortunately, its a pdf and the name/source of the document is not shown)

The only ones that were touched were those that went to the block, so I will likely check first if the new PCM doesnt solve things. And if not, I will confirm O2 sensor activity with the jumper myself. And then possibly figure out how to remove the cover from C1 so I can probe right at the connector while its still connected to see if any signal is making it back. In any case..will update.. thks

oldandintheway

Well....PCM arrived early, put it in, but now I cant get the engine to idle. It cranks, turns over but then immediately dies... (no issues with the old PCM starting, so I put that back in for now)..

followup: apparently I need to do a passlock procedure on it....in progress

So I got the engine working with the new PCM...and I saw activity on B1S1 and B2S1 for a little while in the scan tool. Generally, they were higher voltages... but then it stopped and read a solid 0.450 V

oldandintheway

Did another round of scan tool monitoring today. Watched sensor voltage graph as engine warmed up. I think same response as yesterday so maybe PCM is not getting killed. I get a very slow responding B1S1 followed by slow responding B2S1. Not really oscillatint..starting high (0.8v +) and then slowly meanders down. I think if I hit the gas quickly it will come down to below 0.45v but generally stays high and then after 5 minutes..it just sits at 0.45v steady. Didnt see activity out of B1S2 or B2S2.

oldandintheway

@oilcanhenry Well....my 3rd set of sensors arrived today. I was sort of waiting for them before getting back underneath as its just too frickin hot here. I waited until 11 PM and went out, swapped all 4 sensors (and added some 2 ft extenders to make my life easier in the future) and amazingly enough...precats were bouncing around full range... and system went into closed loop. It was the frickin sensors...had 2 sets of **** sensors..3rd ones had excellent reviews and are working fine. Tomorrow I will drive around a bit and see if I can get all my I/Ms to become ready so I can smog it...but major hurdle passed.

Sincere thank you for your sasistance and extreme patience with all of my ramblings. I was trying to be explicit, detailed and comprehensive in my postings for others in the future..
I guess one moral of the story is..when you buy oxygen sensors off eBay..make sure to buy ones that have excellent feedback.

oldandintheway

Well...looks like a spoke to quickly.. upstreams working.... downstreams now getting P0140 and P0160.. i suspect more bad sensors... if it comes down to it..I will start new thread based on those..

oldandintheway

new Bosch 13474 post cat arrived today..installed...seems to be working fine...after multiple sets of bad sensors..this thread is frickin closed !!