Rough !!!

4 wire . I think I had 12 volt on one of the wires but i dont recall. What i do know was the voltages were the same as the known good 02 sensor connector. Not sure how the 02 sensor works if i give it a sniff of brake clean. Short to ground is possible

on a four wire 02... one is the power wire, one signal wire and two for the heater circuit.

unplug the 02, with the key on engine off what is the voltage reading on B1S1 on your scan tool.

if I disconnect the o2 sensor the scanner shows 0 volts . there is no bias voltage or any backup. if I reconnect it shows the same low reading. when I had the harness probed there was 12 volt at the power wire. the other 3 wires I had some voltage just like all the other 02sensor harness connector .

It should have gone to 0.

this is a little tricky to do... with the sensor unplugged, back probe the signal wire with a T-pin. If the wire is close enough, touch the positive battery terminal with one finger from one hand and touch the T pin with a finger from the other hand. Moisten your fingers to help... do this test with the key on and read the voltage at B1S1 while doing the test.

If you cannot reach the T-pin, connect a jumper wire to it so you can. Hold the jumper wire between two fingers on hand and put a finger from the other on the positive battery terminal.

Don't worry, this will not hurt you or the PCM. The signal wire IS NOT the 12v wire... remember two same colored wires are for the heater, the other two, one is the 12v the other is the signal.

What voltage do you get.

This simple test can test the integrity of the wiring for the 02 if done correctly.

I will check it out and see what happens.

usually I see that in these cases, the owner has thrown a whole bunch of parts and done several other things at this point, however, I have not seen that here. What have you replaced and cleaned to date?

spark plugs and boots , plugs were worn out large gap , some weak coils showing 10k length on spark tester. cleaned maf sensor. o2 sensors were never replaced high miles on them replaced those. I tested and cleaned the electric throttle plate and it opens 100% command at wot. im assuming injectors are lean but havent had a chance to balance test them.

is your MAF an IAT and MAF combination? you will have more than 3 wires if so.

yes its combine.

many have cleaned the IAT thinking that the did the MAF when they are combined. Check closely and make sure you got the MAF. If you have MAF data, low Hz or voltage would indicate a dirty MAF. This causes more unmetered air to enter and a lean condition.

I looked at you scan data... your MAF voltage is below 1v at idle and at 3k RPM its only 2.9 then drops out... look closer at that MAF.

I see the maf sensor and cleaned it. I also see the iat sensor resistor. it still is the same rough idle stalling

their could be other issues but one thing is clear, that B1S1 02 is not operating at idle. You got it to come alive by putting the car in drive or reverse... this suggest to me that this is a wiring problem. The 02 does work.

Trace the wiring harness back. Look for contact points on the engine, trans, frame or even the shift mechanism.

Its evident that stress creates a good signal. You got voltage readings while probing the connector, the connection maybe a potential problem. Stress on the connector maybe causing a good signal when your probing. Start with the pins on the connector and work back to the PCM.

This is a pain staking process... you have to verify every step, it can be so easy to miss an open. I'm convinced, that wiring from the PCM to the 02 is the problem.

The odd thing is when it becomes active in drive or reverse , the idle is more rough to stalling if standing still . Why would it do that is odd. Put it in park and it wont stall but its rough

won't know until the 02 issue is resolved.

If you get the 02 working, clear all codes and memory. Let the engine run and put out new data. Will be able to diagnose as new data is available.

At best, things might clear up and run fine. If not, move on to the next set of data and resolve that issue.

I did the backprobe of the o2 with it disconnected. Wet my finger and touched battery it went to 1.2volts. I reconnected o2 and did it again 1.2volts while running all it did was went up to .35volts while downstream stead .045 cant drive it higher than .35volts with finger in battery. However if i put brake clean than it would go to 1 volt and slowly go back lean of .055

Maybe injectors

at least 1 volt is what was expected. trying to get it higher is not what the test is about, so you're good.

I still believe the harness has a bad connection somewhere. I would hook up my DVOM to the 12v wire and systematically move along the wire from end to end and see if I could get the signal to drop off. I would also do this to the signal wire.

this acts like a bad 02, but if you're 100% sure that swapping 02 had no change, then its the wiring. as you proved the 02 signal comes alive when moving the trans shifter. I think this happens as well when you pull on the wire when testing. if that 02 did not come alive at all, I would suspect the 02.

Even though the idle remains rough with the 02 working, other problems may exist. both 02 have to be working.

The 02 traces from B1S1and B1S2 should not be the same. this goes for B2S1 and B2S2 as well. upstream traces should oscillate between 100 and 900 mv and the downstream 02 should be fixed high. if traces from upstream and downstream 02's are the same, this is indicative of bad CAT's.

verify that the 02 connections are correct. pull the connector to each 02 one at a time and watch your scantool as you do this to make sure your connected to the corresponding 02. although hard to do, it has happened that a connector was attached to the wrong 02. I do not expect this but want to rule it out.

Sometimes its rough and unstable idle at atartup. During that time the throttle seems unresponsive. Instill the idle l becomes stable. Wondering if throttle is part of this issue . Electronic throttle

B1S1 is not heating up to operating temp... note that when you up the RPM's, 3k, the sensor starts to oscillate. this is because the 02 is being heated by exhaust gas.

because you have swapped the 02's and the problem remains on B1S1 the problem is in the heater circuit wiring... unplug the 02, on the harness side for the heater circuit, the two same colored wires, with key on engine off, one should have 12v the other is the ground. if no 12v you have an open circuit. if you have any voltage in the ground wire, you have a short to ground.

I recall that there was 12 volts at the harness when disconnected. the ground wire was very low if I recall. il check again.
some other checks that was done was a injector balance bank one cylinder 1 had 9.5 psi drop cylinder 2 had 9.5psi cylinder 3 had 10psi
bank two cylinder 4 had 8psi drop cylinder 5 had 9psi and cylinder 6 had 9psi

bank one is the lean bank and bank two is rich according to the fuel trims.

Been following this thread for awhile. Have they figured it out?

I had a problem but it was on my Chevy. The B1 S2 was stuck. Wouldn't change. Did the checks. Watched a Scannerdanner vehicle where he had a pickup of same Y.M. and he was diagnosing it at his friends garage.

He said he knew it was the sensor by looking at the Data as he wasn't about to get on gravel. I followed his lead and checked the data as he'd suggested and tested what he'd suggested there to the audience and wound up replacing sensor.

It had been bogging down and causing CEL @ times.

I know this is a different make and model but the wiring seems fussy as others have suggested. Normally if a O2 and dual bank I'll swap a sensor just as a quick way to check. I was rather surprised both of my bank 2 sensors came loose so easily on my 15yr old Tahoe

No torch, Mini Ductor or anything other than a little elbow grease from a sensor socket and spun right out.

Now time to go look at my washer and see if I get lucky as well.