94zLT1

if my 02 sensors are both bad then to what extent can they do to my LT1. Would i throw an SES code.. i quess what im asking is how detremental are to malfunctioning 02sensors on the engine...also i thought the PCM does not read the 02 sensors at WOT?

OBE1 95Z28

As the O2 sensors age, they get coated with exhaust deposits and can't sense O2 content as accurately. You're car will run rich. A general rule of thumb is that they should be changed about every 50K - 60K miles. They are used to adjust your air/fuel ratio during part throttle driving. I believe an OBDI system will only throw a SES code if the sensors wires are open/shorted.

94zLT1

so since the PCM disregards the 02s during WOT what can the 02s tell you(by reading a log) during WOT?

shoebox

The PCM may ignore them, but that does not mean they don't work. You can still read them and get a general idea for a/f ratio. They are not so accurate as they only cover a narrow band of readings.

Injuneer

If, during part-load, part throttle driving, the PCM "learns" that is has to add fuel, because the O2 sensors are telling the PCM tha A/F ratio is too lean, the PCM will use what it "learns" (block learn multipliers) to calculate the fuel required for WOT (actually, its power enrichment - PE - mode, and it occurs at throttle openings less than "WOT", as a function of RPM)...... So, if you O2 sensors were causing a "false lean" at part-load, part-throttle, and adding fuel the engine doesn't need, it will continue to add extra fuel the engine doesn't need at WOT. That will make the already "too rich" target A/F ratios used in PE mode even richer, and knock the power down.

Additionally, if the O2 sensors are causing the PCM to add fuel that isn't needed in closed loop, it can foul the plugs, or even run so rich that is starts to wash the lubrication off the cylinder walls, which will obviously be detrimental to the engine, and power.

If they aren't working correctly, then need to be replaced.

RansZ28

Which O2 sensors can cause the "richness"?
Cheapest place to buy?
How to install?

joecool72

I believe it's the upstream 02s that cause the richness. I changed my 02s about 2 months ago and just recently changed my spark plugs. All 4 plugs on the passenger side had gaps ranging anywhere from .060-.065 whereas stock gaps are .050!

I got factory stock Delco replacements, too. I read about other brands being problems so I just stuck with stock. And you'll have to remove the starter to access the passenger side 02. And have a torch ready to remove them. The tech at my shop had to use it because they were frozen.

OBE1 95Z28

Your front 2 (left and right bank) O2 sensors adjust for the air/fuel ratio. The rear O2 sensors monitor you cat for failure. I recommend the AC Delco O2 sensors (original equipment), some people have had issues with Bosch O2 sensors. You'll need an O2 sensor socket to remove/replace your O2 sensors as the you need clearance for the wiring harness attached to the sensors. As stated above, it's common for the sensors to "freeze" in place. As stated above, a torch will come in handy. Buy the sensors from one of the discount GM suppliers like Dal, Team Chevrolet or Jason Cromer.

94zLT1

This sucks..i thought i could get at the passanger side o2 sensor to get it off without dropping the y pipe but it looks like i gotta drop the y to get at it..damn

btw..i have MAC headers and MAC y pipe