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new guy here looking for help.
have an 08 cobalt ss with a zzp tune I got into the file and they have a some stuff disabled like all the bank 2 02 stuff ( there is no o2 sensor there or cat) im not sure how much im allowed to say but ill start with im using this car off road but would like all the monitors to show clear and passed for my own piece of mind. how do I go about doing this I have an MPVI2 thanks
Do you have a check engine light? If you have no cat the second o2 isn't going to be good for monitoring anything. Turning the related dtcs off would remove a CEL if you had one. It sounds like the tune is what you would want for a no cat set up. The second o2 monitor just makes sure the cat is doing its job. If there's no cat and no o2 sensor, you can't really monitor and there isn't anything to monitor, right?
I understand what your saying I'm pretty sure there's a way to make the computer believe that test have been run an monitors are set even though they are not doing anything.
I think I get what you mean. Like to appear in data form that the test is being run and no check engine lights. I'm sure there is a more modern way but I know you can put a spacer in with the O2 sensor as an old school approach but that would require the second o2 sensor and a place in the exhaust for it. Hope that made sense. If there is a more modern approach others may chime In.
With the specific codes you mentioned being disabled, the emissions readiness tests will not cycle. You will need to re-engage the codes, install a downstream 02 sensor and go through a few drive cycles.
There is no spoofing the rear 02 to show it's OK when it's not OK.
Like fella above said, you have to install the rear 02 after the cat and do a couple drive cycles for it to complete the check.
If you have no cat, then the rear 02 will fail the emissions check.
If you have no cat, but disable the DTC for it, then the emissions monitor will say "Not Ready" and with just 1 monitor being Not Ready you will still pass state emissions.
If 2 monitors are Not Ready, they will not pass state emissions. At least that's how it works most places.
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Originally Posted by ZeroBoostBuick
I agree for the most part except you can use a spacer, for example a drilled out spark plug antifouler. It screws into the o2 bung and the o2 sensor screws into it. Essentially it moves the o2 sensor out of the direct stream of exhaust tricking it. It's an old school technique that works with no cats while leaving the emissions testing in place.good tip on the one not ready still pass info. Didn't know that. The spacer would be useful for those without tuning capabilities or if any state has different rules. Otherwise, just turn the dtc off like zero describes
You can try a potentiometer, it's a 3 terminal resistor that will control the readings to the ECM. You can manually adjust it to fool the ECM, if it works right you won't need the cat or rear o2 sensor. Google it for a description of how it works. You can wire it in at the ECM just follow the wiring diagrams. If you do this hide it so inspectors can't see it OK?
Thanks for all the info..
Carotene. That's a good idea I'm going to give that a whirl. Very disappointed with zzp telling me they have no emissions problems when it obviously could never pass with the way they tuned it. I come from the VW world and all my 1.8t's and 2.0t's were tuned with no downstream o2 or cat and never had an emissions problem.
To be honest I personally don't think the second o2 sensor would ever be needed if the engine is tuned right in the first place. It's not easy to get it close to perfect but when you do the numbers would be great.
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Originally Posted by carotene
Agreed, I think the second o2 is just to protect the cat and make sure it is working. Runs better without it in my opinion -no cat protection enrichment and cat restriction :)