Removing rear O2 sensor on 01-newer PCMs -- Things you should know

if you have a older vs of hp it will read and flash a bin file. the new vs will not.

So, since someone bumped it. Anyone notice even with the diag tests disabled in TT that sometimes it'll still want to run the tests briefly? Unless it something else, can still randomly rise -10 to -20 ltfts gradually for like a minute then it drops back to normal. Literally only does it after I fill up, the car is warmed up, turn it off, fill it up, drive off, mile or 2 later ltfts rise then drop back to normal a couple miles more down the road.

that sounds like the evap it can mess with your ltft's. i deleted mine, it dont do that crap no more.

So it may have been discussed in this thread, but I cannot seem to find it. Will the O2-emulator (such as the one sold by ZZP) eliminate the cat-diagnostic check?? ZZP has free shipping today, and I may take advantage of that.

Sometimes it does, not always

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Originally Posted by SgtMarshal

Sometimes it does, not always

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Any idea why it would work for some but not others?? Seems like it would be an all or nothing deal, unless something else was screwed up in the PCM or secondary O2 sensor wiring??

Trannyman, aka Dave at TEP says the o2 sim won't fix the catalytic converter diagnostic

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Originally Posted by 97AutoXVette

So it may have been discussed in this thread, but I cannot seem to find it. Will the O2-emulator (such as the one sold by ZZP) eliminate the cat-diagnostic check?? ZZP has free shipping today, and I may take advantage of that.

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Don't think so. How I think it works is the test runs the car rich then it looks for the rear 02 sensor to see that then it stops the test. If there isn't an 02 sensor then it can't stop the test until it times out after so long.

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Slightly resurrecting a dead thread (but hey it's a sticky):

The temp for CAT Diagnostic Enable Coolant Temp should really be like 285 instead of -285. The diagnostic will run anyway if it's set to -285 because it will always be above that temperature. It would happen once every drive cycle for me until interrupted by hitting the gas hard or something (the wideband would go way rich, like .68 lambda). After it was interrupted, it wouldn't run again, but it was still annoying. Setting it to a high positive number has kept it from coming back.

I read the entire thing tonight. Do us newbies get any achievement awards? There was usefull information and as always there was a little drama in there but at least it was kept pretty civil. I'm so new to tuning I don't even have a way to hook my Commodore 64 up to my OBDII yet. Anyway, I'm looking for a paper (yes a book, with a cover, bindings and PAPER) back or hardcover book you suggest to read on tuning. I'm so new I had to look up ltft and stft. Hoping to get to know and learn from each of you guys.

https://calibratedsuccess.com/

https://www.amazon.com/Engine-Manage...ine+management

^ That's the book I have. Very good information. The best information for our specific platform is in this pcm tuning forum. Lots to read and absorb!! I'm not sure what you are planning to tune with but the Commodore 64 won't cut it! LOL