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P0420 and O2 drama

I can't say that Bosch are junk, I have never tried them... but I've used Denso O2 sensors and not had any problems. A new Denso sensor will probably outlast the vehicle unless you have an unusual setup. No issues with them in any of the 4 3800 vehicles I have owned.

60K mile O2 sensor change sounds like throwing money away.
 


The non-fouler trick looks interesting. Not sure if I'd rather try this or just use a MIL eliminator. Seems like pulling the sensor out of the stream would have the opposite effect, but apparently not. I prefer to fix problems rather than mask them, but if the system is that particular, to hell with it. Anyone know the right size plug non-fouler is necessary by chance? Seems like there was an issue with the factory ECU that even the NA guys paid to have it tuned out, but I don't recall what exactly, maybe something with the trans strategy. It was a mail-in type deal where you sent in your ECU as a core and got another one back. I looked into it enough to know that I wanted a Blackbear tune when he was on tour instead of paying for the ECU swap, but I passed him up when he came through. I sent a buddy his was though with his GXP and that thing was like night and day. They tuned it on the street...hahaha.
 
MIL eliminator wont solve your Cat Diagnostics issue. Your car will need to think the cat is properly working.
 
A little insight here.
Stock AC Delco isn't what they used to be....literally. GM switched their supplier years ago, and if memory serves me correctly they're Denso on some.
For the older W-bodies, the O2 sensors that had the longer tip, with the long cut vented inlet in them were the best. They read better than the new ones that I refer to the "gun barrel" design simply because they were sensitive enough to read the actual exhaust pulses faster. The aftermarket ones as far as Denso and Bosch don't, and typically throw a P1133 code.
In the end, you just run what you can get. I'm more likely to go to the JY and pocket a used stock one than go fight with warranty at a parts store.
 
Reptile said:
A little insight here.
Stock AC Delco isn't what they used to be....literally. GM switched their supplier years ago, and if memory serves me correctly they're Denso on some.
For the older W-bodies, the O2 sensors that had the longer tip, with the long cut vented inlet in them were the best. They read better than the new ones that I refer to the "gun barrel" design simply because they were sensitive enough to read the actual exhaust pulses faster. The aftermarket ones as far as Denso and Bosch don't, and typically throw a P1133 code.
In the end, you just run what you can get. I'm more likely to go to the JY and pocket a used stock one than go fight with warranty at a parts store.
Click to expand...

I ran ACDelco in my 97 for over 23k miles and no issues. My 06 had Denso in it and that's what I put back in. No issues either
 


I wasn't even going to remove the cat, but isn't that what an MIL elim does is allows for this by altering the reading via resistor? Is the GM / Delphi setup different in this regard? I've dealt with the Delphi stuff before...Harley ECUs. They are quite the PITA and I don't think anyone has really even cracked the things "wide-open" yet. There are still either unused or unknown strategies in there.
 


Dammit, I just saw your post regarding cat efficiency...I assume this is a thing with these cars and explains the problem with MILs. I will try the non-fouler trick. Thanks for all the help!

At 170k could very damn well just be a failed sensor. Maybe I'll do a new sensor AND a non-fouler mod? Forgot to mention I removed the exhaust resonator a few years ago due to driveway clearance.
 
To my knowledge what the MIL eliminator does is sends back a "good" signal to the PCM that tells it the O2 is working. BUT then when the PCM runs cat diagnostics and the signal does not change it will think the cat has gone bad and will make the car run rich and set the P0420 code. [h=2][/h]
 
Iceman6669 said:
To my knowledge what the MIL eliminator does is sends back a "good" signal to the PCM that tells it the O2 is working. BUT then when the PCM runs cat diagnostics and the signal does not change it will think the cat has gone bad and will make the car run rich and set the P0420 code.
Click to expand...

No. I used the ZZP o2 simulator on my 97 and never had a p0420 code. The tune from Will hasn't given me a 420 code either
 


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