Right bank killing O2 sensors?
02-01-2011, 08:28 PM
#1
Right bank killing O2 sensors? So I bought some AC Delco sensors online after my 3 year old sensors finally started getting really slow, then shortly afterwards the right bank started reading a false lean, leaning the BLM's out at 160 and 200 on the short term trims. My wideband of course is reading 10.0 and the engine then starts chugging and bucking bad of course from the excessive fuel. Swap the O2 to the driver's side, but it is already shot. So I put some new O2's in yesterday, it scans and runs great, running within 3% on the fuel trims, wideband staying between 14.4-15.3. However tonight, a mile from my house, once again, it starts doing it again, so they lasted about 100 miles of driving today. What could be killing my O2's on one side of the engine? Pulled the plugs on that side, they look fine, light brown, not oily, no specs of detonation. All the injectors were exactly the same resistance, plug wires checked out fine as well. I have some blowby at WOT, could that be killing it? This oil change I put in VR1 10w40 synthetic, could it be the high zinc ZDDP content be killing the sensors?
02-02-2011, 04:42 PM
#6
Didn't change the plugs, they weren't fouled, and still looked good. Just changed the oil back to some High-mileage Mobil1 10w40 and put in some new O2 sensors. Re-flashed the PCM tune with WOT BLM locked at 128, checked all of the header bolts, they were tight, the collector gaskets are sealed with copper RTV. Found no visible leaks on the headers that I could see, but then again, it is hard to see the whole pass side header from top or bottom. Drove around 50 miles so far, no datalogging yet, but it is running great. My LM1 wideband shows great near 14.7 a/f ratio cruising, city driving, and part throttle so far.
Going WOT, whether it be starting at low rpm in higher gear or higher rpm in low gear, it reads the commanded 12.1-12.3 on the gauge (I'm running E85) then all of a sudden, literally like a switch reads 20.1, which is what it reads in fresh air. The engine however sounds the same when this 'switch' happens and no noticeable change in the way the engine is running/pulling either, but of course, I back off the gas as soon as it shows 20.1, then when I touch the throttle again, it instantly flashes 10.0-10.2, then back to a normal approximately 14.7. What the hell is going on here??
Going WOT, whether it be starting at low rpm in higher gear or higher rpm in low gear, it reads the commanded 12.1-12.3 on the gauge (I'm running E85) then all of a sudden, literally like a switch reads 20.1, which is what it reads in fresh air. The engine however sounds the same when this 'switch' happens and no noticeable change in the way the engine is running/pulling either, but of course, I back off the gas as soon as it shows 20.1, then when I touch the throttle again, it instantly flashes 10.0-10.2, then back to a normal approximately 14.7. What the hell is going on here??
02-02-2011, 05:14 PM
#7
I think I may have found the wideband problem now. The wideband is installed at the y of the y-pipe, and with the engine running, with a bright led flashlight, I wasn't able to find anything at all on the pass side, but on the #1 primary slip fit, I noticed it had a slight leak there, with about 1/4-1/2" black mark on the top, it was previously sealed with copper RTV too, so it probably just needs a reseal, but it is too small, just larger than a pinhole size leak, to be causing the problem, plus it is on the driver's side, not the pass side.
The culprit of the wideband reading, I believe, is a leak at the ypipe to catback, it was pretty much chugging out exhaust from there, and is only a few inches after the wideband, so I assume once the airflow from the engine reaches a high enough point, it goes from reading the exhaust to sucking in the fresh air from the big leak at the end of the y. Is this an accurate hypothesis?
The culprit of the wideband reading, I believe, is a leak at the ypipe to catback, it was pretty much chugging out exhaust from there, and is only a few inches after the wideband, so I assume once the airflow from the engine reaches a high enough point, it goes from reading the exhaust to sucking in the fresh air from the big leak at the end of the y. Is this an accurate hypothesis?
