So, back in March I had the 02 sensors on my '92 replaced. As always, I specified AC Delco to my mechanic and of course he said there's no other choice but. In went two AC Delco AFS22 sensors to replace the originals from '92.

Around late May/early June, my car threw a code 63 (right 02 sensor circuit open). It would come and go, so I lived with it for a few weeks. A while later I then got a code 44 (left 02 sensor lean) and that prompted me to get ahold of my mechanic and see what was going on. Brought him the car back and after lots of testing, he determined the right 02 to be bad and replaced it with another AFS22. Less than a week later, another code 63. Same side he just replaced. Using my Auto Xray scanner, I could see that the ECM flat out refused to go into closed loop, even after 20+ minutes of driving. If it did go into closed loop, it was after a short full throttle blast, but it would go right back into open loop again a few moments later. At idle, voltages on the left would flip from lean to rich slowly and under acceleration they would drop down to 20-40 mV and STAY there. On the right, voltages would hang right around 450 mV, moving very little whether I was idling or accelerating. I was driving my mechanic nuts having him check other things such as ECM grounds and wire connections. Couldn't find anything wrong. He kept telling me there was something else wrong with the engine that was causing the weird 02 sensor readings.

Then, I came across this post: http://www.turbobuick.com/forums/tur...or-issues.html.

Without even giving it more than a minute's thought, I went ahead and ordered a pair of Denso 234-1001 sensors and had them installed last week. I've had the car out several times since then, with the scanner hooked up, and my 02 sensor readings are right on the money. I'm seeing BOTH sides now flipping lean to rich (100 mV - 900 mV) and doing it consistantly. No more codes either.

I believe '92 and '93 both used the same 02 sensors, as '94 went to a new heated design. Has anyone else out there with a '92 or '93 had any issues with their 02 sensors, in particular the AFS22 from AC Delco? Some of the folks in the thread I linked to are claiming AC Delco has been slipping in quality over the past few years. Man, I'd hate to think that.

Ron

 

Don't own a '92 or '93 but never had any O2 on any car go bad - maybe because the warranty out here is forever and a lot of the stuff you read is urban legend (or marketing by Bosch). If there was a problem, there'd be a long line at dealers for replacement under the emissions warranty or a recall - there isn't and never has been. But there are things that will kill an 02 - coolant from a blown head gasket; which will usually lean it out enough to spit the 44 before it's shot. Improper installation; particularly if someone slathers too much anti-seize on the threads. Other than that, signal wires get burned when they get too close to the Headers as do connectors. You mechanic needs to datalog to find if there's a good reason for the 44 - like a vacuum leak or busted header check valve and check compression - which in the old days we checked first and I wish shops would go back to doing that first (instead of thinking it's some sensor or the ECM).

 

I'm running an Accel DFI unit in my 85 and after a a few years had to replace the O2 sensor. I bought the Accel unit, it went bad again after a couple hundred miles, as did the next one, so I did some research, liked what I read about the Denso sensor, figured out which part number would work for my application, and it's worked like a champ since for several thousand miles now. I can't speak to the AC Delco unit, and I don't know who Accel gets theirs from, but I definitely am a fan of the Denso sensor!

 

I have a 93 and had a 92, never had that problem.

 

I'm currently running Bosch 02 sensors in my stock '92 and haven't had any problems. They were much cheaper than the O.E.M. Delco's and much, much, cheaper than the high-end Densos.

However, I have heard of LTx and L98 engines (particularly modded ones) that didn't well take to Bosch sensors due to calibration parameters markedly different than the Delco ones. Once the sensors were replaced with O.E.M., the problem went away.

Regarding sensor failure, I know problems can also occur if you get even a dab of anti-seize compound on the sensor tip.

Even oil or grease on your fingers that gets on the tip can cause them to fail early, that's one of the reasons why they come with a protective plastic cap.

 

I went thru the o2 headache earlier this year with my 94. the right o2 went bad and i repaced it with a bosch. It ate it in a month - i relaced it again with a bosch and it ate it too. Then i got a delphi and my car is happy with it. I know people have different results with different cars but mine likes the delphi o2.