Hey guys, looking for some info from anyone with extensive tuning experience.

Something I just recently started seeing is on tuned cars with p0410s and p0420s(etc) turned off that the cars are failing inspection. Because the PCM never sets the I/M flag to "YES/READY" becuase with the codes disabled it never runs the diagnostic and therefore never gets a pass result. Not sure if this is this result of the indiviudal tunes, the tuning suite used, or if this is just something that finally becoming apparent since newer vehicles requiring more ready I/M flags are finally coming up for inspection.

Any thoughts?

 

My car is tuned to ignore the absence of a Cat, and I passed NY State's "High Enhanced" Emissions Testing.

 

It shouldn't be failing an IM monitor. Turning the codes off only sets them to Class D no error reported. The DTC will still run the test, it just won't report if it fails. A good example of this is those who removed the cat and rear O2. P0420 and associated rear o2 codes can be shut off and the catalyst IM will still pass.

Edit: I see you are talking about p0420. I have yet to see a cat deleted car not set an IM for the catalyst to ready after setting the faults to no error reported.

Edit Again: If you are tuning cars with newer PCMs (LE5, GTOs, etc) and are disabling the post cat o2 ready check from running, this may be giving you problems. The DTC selection area should not fail an IM but the other parts in engine diagnostics that allow you to directly disable DTC programs from executing could fail/freeze an IM monitor.

If you disable tests on this screen, then yes you'll probably freeze an IM:



If you disable DTCs in this screen, it shouldn't freeze IMs:

 

So your saying that what I am seeing is then most likely a "tuner" issue, and these guys arent changing the DTC from an "A" status to a "D" they are simply adjusting the "run" parameters for the diagnostic outside of the normal operating range of the system. and then it never actually runs, so when you clear codes or flash the ECM it wipes the flags and they never reset.

Is modifiying the status of the code something most tuning suites use as the primary DTC eliminator?

Its pretty obvious whats going on then I guess, do you know which suites allow DTC parameter modification?


So I need to tell my customers to have their tuner change the STATUS of the DTC, not modify the PARAMETERS

 

the monitors still say ready, the codes just dont show failures.
All tuned cars should pass

 

Kind of. Its more with the software written onto the PCM. On an LSJ, its just a basic run of the mill PCM. When you delete the cat, change the code from A/B to D, all is well.

On a GTO if you delete the cat and physically remove the rear o2 sensors and change the codes from A/B to D all sorts of weird things happen, one example is it likes to enter a lean cruise mode for a while.

Most tuning suites do not allow modifying the DTC codes themselves, only setting which fault they report. I've found that the ones HPTuners allows you to modify are only there because removing those physical items associated with the DTCs yields strange results, thus the customers requested the ability to modify the DTCs in question and the result is what you have above.

If the tuner modifies the DTC program, its usually for good reason. Just having the ability to do it usually means theres a problem if you don't. A big generalization but sometimes you have to live with either the car having a quirk or two or not passing emissions. If you are dead set on getting them to run you could try and leave the rear o2s installed and simply set p04xx to class D and allow the DTC to run with no errors when they fail.

 

What I am telling you is that the flags DO NOT say ready. If it doesnt run the test, the test never passes, So it fails.

 

Some people have only tuned a limited number of models thus not aware of the ability to physically alter DTC programs and not just the class under which a fault sets.

I'm sure the ones you are seeing not set ready on IMs are the same generation PCM.

 

Im thinking he is referring to tuning it and right after sending it to the emissions check before they have completed the cycle. Your CEL may not light up during this time until it is ready, hence they may not have changed the DTCs.

just my 2 cents.