I've tried searching the threads for help on this so...

I Installed an Interceptor gauge a couple of weeks ago and when I brought up the o2 voltage for bank 1 and 2, bank 1 was all over the place from 080 to 900 or so whereas bank 2 was at around 450 consistently. So I replaced both sensors with factory sensors and that resulted in zero change. I have a Nelson tune with the rear sensors turned off. I also have Dynatech headers with high-flow cats. I am trying to figure out where to start looking to find the problem. Is it electrical (pinched harness from a trans rebuild, or bad coil on that bank), mechanical (bad cat), or fuel (something with the injector(s))? The o2's that I pulled out were BLACK. Is bank 1 cyl 1-7, or cyl 2-8? I've had a problem with #5 and 7 primaries burning plug wires, so I use sleeves along with wrap on the prim. and wires. I can't really think of anything else that might help figure this out other than I live in Colorado at around 7000 ft elevation (tune causing a problem?). Any help would be great...thoughts anyone?

 

Anyone?

 

In closed loop your o2's should be all over the place. 90 to 900 sounds very good actually. Long story, but your pcm is looking for 14.7:1 and that's in the middle (pretty much) so the up and down is your pcm "switching". WOT, it should be steady.

The dynatechs, or any set of headers where your exhaust stream cools down some, you might notice some poor code issues, or mileage issues due to the inconsistent switching cuz the exhaust stream is cooler.

Bank 1 is 1,3,5,7 and Bank 2 is 2,4,6,8

 

Well if that's the case, then the other sensor must be outta whack, cuz it is at a steady 400-450 all the time. I'll have to check tomorrow to see if the other one steadies itself at WOT. So I have bank 2 steady at around 450 and bank one all over the place. What does that mean? The distance from the heads and the o2's on both sides is about the same distance. Oh, and bank two long trim was about one point higher than bank one...or bank one was one point lower....I guess it depends on how you look at it. hahaha

Thanks for the input, btw. I didn't know that there was that big of a range sweep from the o2 sensors. That was my guess re: which side was b1, but I figured I'd better double check before I tore something apart. I'm used to inline-four motorcycle engines...only one bank to choose from.

 

Mine does the same thing, I think because you are interrupting the voltage to that sensor with the gauge. If the O2 system is set up to monitor wide band vs narrow it may act a little different. I may be wrong but that seems to be plausible... But, bouncing all over the scale is correct,until as said before, you are at WOT. My bank #1/ sensor #1 readings do seem to be lower than the others all the time after installing my gauge though and I don't have a wide band O2 setup yet...

Post up if you get it figured out...
Later

 

Check for a bad wire on the bank 2 sensor somewhere if its new. With the B2 o2 staying at 450, your truck is staying in open loop, probably why you are burning so rich.

 

Bank 2 was at 450 with the old sensor and when I installed the new sensor nothing changed, it stayed at 450. Open loop sounds reasonable, but do the banks operate independently from each other in that way? Bank 2 had quite a bit more soot than bank 1 did, so that does make sense. If that is the case, then what's the fix? Is it in the tuning or an electrical fault somewhere?

As far as wideband goes, I'm not set up for that at all. The old sensors were the original factory parts and the new ones are oem from the dealership. I wonder if other people are having the same results with that gauge (bank 1 reading lower)? On the oil pressure setting it reads 65523 but doesn't change at all with rpm. hahaha I've unplugged and replugged the obdII connection to make sure that wasn't the problem.

You should be able to choke your truck just like a disobedient wife. hehehe

 

Not sure either, maybe someone else will chime in with some useful info...

 

I think it is actually the scangauge. I know one of the o2's on my scangauge (don't remember which one) always reads 450 no mater what is happening with the motor. The other's switch like there supposed to in closed loop.

 

There was a post about this here or ls1truck about this. IIRC, the pcm reads one side live (080-900) and the other as stoich (450). You can switch the O2s and wiring and nothing will change. It is along the lines of what Redhot was saying about the voltage interrupt.