1998 yukon Mystery p0300 and rough idle still

[OilBurner2003]

Are O2 sensors new? Denso's work good on these and are cheaper.
Did they fix the burned wiring? Still chasing P1351?

02's are brand new, couldn't remember the model that we got for the life of me, I think they were Denso's. They didn't tell me it was burned wiring, that's just what I'm guessing. Man, the loops I've been through. First I'm told it's a bad O2 sensor which was throwing the code, then I'm told it's being caused because of a exhaust leak. I suppose I'll see what I'm told next!

 

[Fless]

I can't hear it, Mechanic says I have a big one somehow. Replaced the whole exhaust myself and sprayed with soapy water afterwards, couldn't find anything. B1S2 has no reading, stuck at .450V. Maybe I messed up at the flange and it's leaking there, would be news to me. It had a p0140 even before I changed the exhaust, wonder if it's either the leak or a burned/Shorted wire. Looks like it's a upstream sensor before the cat. Or maybe not...I had this all memorized a couple months ago. Other sources tell me it after the cat, which again, is brand new.

B1S2 is the post-cat sensor. Driver's side, 2nd sensor.

 

[exp500]

I was referring to post 267 about the burned wiring.
At this stage, you have done everything but test drive while monitoring live data for misfires. I'm really thinking Ignition miss. I would test drive at 25/35/45/55 just to verify it is not one specific cylinder. I'm thinking plug wires/ coil wire.

 

[OilBurner2003]

I was referring to post 267 about the burned wiring.
At this stage, you have done everything but test drive while monitoring live data for misfires. I'm really thinking Ignition miss. I would test drive at 25/35/45/55 just to verify it is not one specific cylinder. I'm thinking plug wires/ coil wire.

I've done a lot, sir. Those Included. It is beyond my limited knowledge at this point. But I do agree with you on ignition miss, I just don't know what else to check. Everything spark related is basically replaced, and I'm not sure how to check PCM wires, (Which is where that charred part of the harness is.)

 

[exp500]

Post pics of the damaged harness, we may have you open it a little to look at individual wires.
Do you have your old plug wires? Try changing the coil wire.

 

[OilBurner2003]

Post pics of the damaged harness, we may have you open it a little to look at individual wires.
Do you have your old plug wires? Try changing the coil wire.

Trucks not currently in my possession, will post pics when it’s back.

 

[OilBurner2003]

Post pics of the damaged harness, we may have you open it a little to look at individual wires.
Do you have your old plug wires? Try changing the coil wire.

Post pics of the damaged harness, we may have you open it a little to look at individual wires.
Do you have your old plug wires? Try changing the coil wire.

What a morning. Long story short, got the truck back. Said he didn’t have time to look at it anytime soon. Got it back home and already tore the damn thing apart, I’m just too curious. In the picture is part of the wiring harness that has a burn underneath, I’d have to take off that wire Loom to get a pic. Not sure how to either.

 

[east302]

Did you get that loom opened up enough to see what’s going on?

 

[OilBurner2003]

Did you get that loom opened up enough to see what’s going on?

Yup, couldn't find anything.

 

[east302]

Just the outer plastic loom was melted - didn’t burn through to the wires?