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Thread: High flow cats and CEL's

  1. #1
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    High flow cats and CEL's

    Wanted to open some dialog on adjusting tunes so that when one is running high flow cats, it doesn't trigger a CEL. Specifically this is for codes P0420 and P0430, Catalyst Efficiency Below Threshold.

    Basically these are triggered due to the amount of o2 readings downstream reading too close to upstream. I haven't looked within HP Tuners to see where one may set the threshold for these values or if it exists. I believe if this exists we may be able to eliminate the need for running foulers.

    Thoughts/ideas/recommendations much appreciated.

  2. #2
    Quote Originally Posted by wbt View Post
    Wanted to open some dialog on adjusting tunes so that when one is running high flow cats, it doesn't trigger a CEL. Specifically this is for codes P0420 and P0430, Catalyst Efficiency Below Threshold.

    Basically these are triggered due to the amount of o2 readings downstream reading too close to upstream. I haven't looked within HP Tuners to see where one may set the threshold for these values or if it exists. I believe if this exists we may be able to eliminate the need for running foulers.

    Thoughts/ideas/recommendations much appreciated.
    On a Ford there is a switch to disable rear 02's. Along with disabling that strategy go under engine diagnostics tab and turn off the codes p0420/p0430 and all bank 12 and 22 sensor dtc's. I some strategies there is a heater switch as well for the downstream sensors that needs to be disabled.

  3. #3
    Looks like in HPT they have the switch under ENGINE_GENERAL tab for rear 02 config and there is a catalyst test switch under ENGINE DIAGNOSTIC_MISFIRE tab. The DTCs will be under engine diagnostic tab as well.

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    Quote Originally Posted by Matt@MMP View Post
    On a Ford there is a switch to disable rear 02's. Along with disabling that strategy go under engine diagnostics tab and turn off the codes p0420/p0430 and all bank 12 and 22 sensor dtc's. I some strategies there is a heater switch as well for the downstream sensors that needs to be disabled.
    Quote Originally Posted by Matt@MMP View Post
    Looks like in HPT they have the switch under ENGINE_GENERAL tab for rear 02 config and there is a catalyst test switch under ENGINE DIAGNOSTIC_MISFIRE tab. The DTCs will be under engine diagnostic tab as well.
    This isn't disabling the rear o2's. It is leaving them on so a car can pass the monitor test for inspection. I should have clarified in the OP.

    If the codes are disabled I am not sure if they will pass the ready test. That is an unknown. I am looking for ways around that part.

  5. #5
    HPT Employee Eric@HPTuners's Avatar
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    I will be adding the parameters that control this in the next week or so.

  6. #6
    Quote Originally Posted by wbt View Post
    This isn't disabling the rear o2's. It is leaving them on so a car can pass the monitor test for inspection. I should have clarified in the OP.

    If the codes are disabled I am not sure if they will pass the ready test. That is an unknown. I am looking for ways around that part.
    my bad not used to States that test

  7. #7
    Senior Tuner mbray01's Avatar
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    The factory gm monitoring tests how fast the o2's refresh, when switching from lean to rich and pre designated intervals, ie a specific drive cycle. Not just sitting still, there is a specific set of variables that have to be met in order for the test to run, usually after a long drive with combo of city and highway driving, the test will run when coming to a stop at a red light. what it looks for is switch speed, slow switch = good, fast speed, like the front o2's = bad. high flow cats will always allow too fast switch speed. my experience has been unless they find a way to change the way the pcm calculates the flow rate of the cat, i either turn them off completely, or if you have to pass emissions, I install 13/16 spark plug non foulers. on big flow cats two stacked will do. drill the first one to accept tip, and leave second one that goes in exhaust alone. this slows the sensors ability see changes. basically fooling the pcm.
    Michael Bray
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  8. #8
    Senior Tuner mbray01's Avatar
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    and its cheap to do. We do this for our customers with older vehicles that want the cel off but don't' want a high dollar factory cat, we will install a universal cat and non foulers. problem solved, no cel, no excessive fumes, which don't bother me, but do bother customers sometimes.
    Michael Bray
    Rusty Knuckle Garage
    Slidell, Louisiana
    20yr Master Tech.
    Advanced Level Specialist
    Custom Car Fabrication, Customization, High Performance.
    GM World Class Technician
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  9. #9
    Advanced Tuner Witt's Avatar
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    Quote Originally Posted by wbt View Post
    This isn't disabling the rear o2's. It is leaving them on so a car can pass the monitor test for inspection. I should have clarified in the OP.

    If the codes are disabled I am not sure if they will pass the ready test. That is an unknown. I am looking for ways around that part.
    You're correct, to pass the readiness tests you have to change the thresholds for the cat and o2 response tests.

    They aren't like older fords where its a single value, there are now multiple tests involved, mainly so a quick response can be achieved after cat replacement to verify quickly that the new cat is working. The monitor uses a weighted value method as well to keep false positives from triggering the ses. The other brand software has 4 pairs of values that can be editted in 2011-2013 vehicles but haven't included them in the 2014 strategies.

  10. #10
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    Thanks everyone. I'll be looking out for the updated beta Eric.

  11. #11
    Advanced Tuner |V3nom|'s Avatar
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    any updates to this? is there a way to fool the pcm with out o2 extenders?
    2008 Sky RL

  12. #12
    HPT Employee Eric@HPTuners's Avatar
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    Quote Originally Posted by |V3nom| View Post
    any updates to this? is there a way to fool the pcm with out o2 extenders?
    Its still in my queue of things to do. Shouldnt be too long.
    Eric Brooks
    HP Tuners, LLC

  13. #13
    Advanced Tuner |V3nom|'s Avatar
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    thats pretty cool. ive seen this done for tacomas by an external controller box wired into the computer but theyre able to get away with no cats with it, although i think it does it different by sending a false signal that says the cat is good.

    will this work catless or will it only work with high flow cats?
    Last edited by |V3nom|; 06-11-2014 at 03:56 PM.
    2008 Sky RL

  14. #14
    HPT Employee Eric@HPTuners's Avatar
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    Quote Originally Posted by |V3nom| View Post
    thats pretty cool. ive seen this done for tacomas by an external controller box wired into the computer but theyre able to get away with no cats with it, although i think it does it different by sending a false signal that says the cat is good.

    will this work catless or will it only work with high flow cats?
    Lets just say... its flexible ;-)
    Eric Brooks
    HP Tuners, LLC

  15. #15
    Advanced Tuner |V3nom|'s Avatar
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    nice! might need this in the future!
    2008 Sky RL

  16. #16
    Have these parameters been added to the beta?

    Thank You

  17. #17
    HPT Employee Eric@HPTuners's Avatar
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    Quote Originally Posted by bad383ta View Post
    Have these parameters been added to the beta?

    Thank You
    A couple of definitions have these, but I need to go and add in into everything. If you need it in something specific, email support.
    Eric Brooks
    HP Tuners, LLC