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  1. #1
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    Default Cat delete be too loud?

    Will this be too loud on a 3.8 NA with stock resonator and mufflers still installed?

    Wondering if I should send it back and pay the extra 75 to get the high flow cat from ZZperformance?

    You might be wondering why I am going thru the trouble of a cat delete. Well, about 6 years ago I kept getting the P0420 code, so I replaced both up and downstream O2 sensors and still got the code. So then I replaced the cat with a magnaflow (Oriellys) and still would get the code every now and then. So I bought an O2 simulator for the rear and boom, no more code for 6 years. Then all of the sudden I got the code again out of the blue, cleared it and kept getting it. So I was puzzled why I would be getting this code because I have an O2 simulator on the downstream so I decided to replaced both up and down stream O2 sensors with Bosch and obviously got the code again. So then I looked at my fuel trims to make sure everything was good and I noticed my long term was slightly high (+4.8) so I cleaned my MAF sensor and now its back down to +2.0 with the short term bouncing around 0.0.

    So back to the stupid P0420, I'm no assuming that the O2 simulator no longer works again but is that possible? I did have it zip tied under neath the car and not up in the engine bay like most directions say to do. SO maybe all the water and salt spray underneath finally worked itself in there and shorted it out?

    I bought another O2 simulator from ZZperformance and will try that again I guess but this time I will put the sensor up in the engine bay to protect it from the road grime. Since I would be under there farting around I thought it would be a good idea to slam in a new down pipe from ZZperformance with no CAT but looking back maybe that was a bad idea and I should just return it and see if the new O2 simulator works.
    Last edited by scha0786; 02-15-2017 at 08:42 AM.

  2. #2
    Killa Bee Scottydoggs's Avatar
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    Default Re: Cat delete be too loud?

    you wont know its missing.

    but depending on your year you might set the cel, might need a tune for it the code not be there.

    98 Buick Regal GS, F body brakes, Caddy STS wheels, tinted tails L36 bottom end, lightly ported heads, 1.95 roller rockers, headers, 2.8, FSIC, 42 lb injectors, a BrandonHall rebuilt trans, DHP tuned and AEM water/Meth injection https://goo.gl/gpV5kW

  3. #3
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    Default Re: Cat delete be too loud?

    Thats what I thought because the one in there is already high flow and has a nice throaty sound already but not too crazy because the stock resonator and mufflers are still present.

    The year is an 2001 3.8 N/A. My last ditch effort to do away with this stupid P0420 is to send in my PCM to ZZperformance to get it flashed without the P0420 but don't like having the car down that long.

  4. #4
    Killa Bee Scottydoggs's Avatar
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    Default Re: Cat delete be too loud?

    being a 01 you need the cat test deleted, not just the code, not sure if zzp does that right or not, it can only be done right with DHP and tiny tuner, or TT with HPT, but most cant seem to make that work.

    with the hi flow cat or no cat your year car will over fuel the tune as it fails the test over and over.

    98 Buick Regal GS, F body brakes, Caddy STS wheels, tinted tails L36 bottom end, lightly ported heads, 1.95 roller rockers, headers, 2.8, FSIC, 42 lb injectors, a BrandonHall rebuilt trans, DHP tuned and AEM water/Meth injection https://goo.gl/gpV5kW

  5. #5
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    Default Re: Cat delete be too loud?

    so which cat do I need to run to not get this code. I have two (2) good O2 sensor and I am willing to return the cat delete pipe and O2 simulator back to ZZperformance and buy the correct down pipe with cat.

  6. #6
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    Default Re: Cat delete be too loud?

    holy crap, the OE GM cat is $900! All other chains only sell magnaflow or walker. I already have the magnaflow and that one throws the code. Is the walker one better?

  7. #7
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    Default Re: Cat delete be too loud?

    I believe you need at least a 400 cell cat to make it happy. A walker will be basically a stock replacement and should fix your P0420 issue.
    2004 Comp G. Pacesetter headers, 1.8 roller rockers, Wizair CAI, HPTuned, 3.4pulley, ZZP transmission, fuel pump and alt rewire, poly mounts/performance suspension, Impala front brakes drilled and slotted rotors.

  8. #8
    Killa Bee Scottydoggs's Avatar
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    Default Re: Cat delete be too loud?

    a factory cat needs to be installed to avoid the cel and over fueling issue.

    if your down pipe is stock still you can hit a junk yard and grab one there maybe, or off a member here maybe. when headers go on the stock crap gets tossed or saved. if saved they might sell it.

    98 Buick Regal GS, F body brakes, Caddy STS wheels, tinted tails L36 bottom end, lightly ported heads, 1.95 roller rockers, headers, 2.8, FSIC, 42 lb injectors, a BrandonHall rebuilt trans, DHP tuned and AEM water/Meth injection https://goo.gl/gpV5kW

  9. #9
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    Default Re: Cat delete be too loud?

    So ZZperformance cat is a 400 cell, I guess I send it back to swap it with the correct one.

  10. #10
    Killa Bee Scottydoggs's Avatar
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    Default Re: Cat delete be too loud?

    thats a high flow cat, instant cel.

    98 Buick Regal GS, F body brakes, Caddy STS wheels, tinted tails L36 bottom end, lightly ported heads, 1.95 roller rockers, headers, 2.8, FSIC, 42 lb injectors, a BrandonHall rebuilt trans, DHP tuned and AEM water/Meth injection https://goo.gl/gpV5kW

  11. #11
    SE Level Member 01Blackgtp's Avatar
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    Default Re: Cat delete be too loud?

    I've done all that and more and still got the p0420 code. failed spoofs, replaced cats, 02 extender, replaced 02s. I gave up and tuned out the damn thing.

  12. #12
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    Default Re: Cat delete be too loud?

    hmm....I give the local junk yard a call and see what they have laying around

  13. #13
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    Default Re: Cat delete be too loud?

    so what tune did you use?

  14. #14
    Killa Bee Scottydoggs's Avatar
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    Default Re: Cat delete be too loud?

    if you have no inspection i can send you a tuned pcm with a non matching vin#, 01 up pcm's wont let me change the vin. if you have inspection you could send me the stock pcm and i could tune it and send it back. the vin# stays the same this way.

    98 Buick Regal GS, F body brakes, Caddy STS wheels, tinted tails L36 bottom end, lightly ported heads, 1.95 roller rockers, headers, 2.8, FSIC, 42 lb injectors, a BrandonHall rebuilt trans, DHP tuned and AEM water/Meth injection https://goo.gl/gpV5kW

  15. #15
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    Default Re: Cat delete be too loud?

    Ok thanks, Ill keep that in mind. I will do some research on this first though. I see there is a thread in the PCM tuning section and would like to read that in full before i make a decision.

  16. #16
    Killa Bee Scottydoggs's Avatar
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    Default Re: Cat delete be too loud?

    you can try to fake the o2 sensor out, but tuning it out is forever and fool proof.

    98 Buick Regal GS, F body brakes, Caddy STS wheels, tinted tails L36 bottom end, lightly ported heads, 1.95 roller rockers, headers, 2.8, FSIC, 42 lb injectors, a BrandonHall rebuilt trans, DHP tuned and AEM water/Meth injection https://goo.gl/gpV5kW

  17. #17
    SE Level Member Keko's Avatar
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    Default Re: Cat delete be too loud?

    Well, my car has been running rich at times, I think this is probably why (high flow cat). I have access to my friend DHP, so maybe I can delete that test. Glad I ran across this
    [Daily] 2002 GTP 40th Ann - FSIC, dp+plog, 3.3", ported LIM, HAI, front+rear sway bars, poly mounts, zzp tune for now :/
    [Fun] 2012 mazdaspeed3 - dp, 3" intake, FMIC, HPFP, Custom tune, lots of other goodies

  18. #18
    Killa Bee Scottydoggs's Avatar
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    Default Re: Cat delete be too loud?

    Quote Originally Posted by Keko View Post
    Well, my car has been running rich at times, I think this is probably why (high flow cat). I have access to my friend DHP, so maybe I can delete that test. Glad I ran across this
    hes needs tiny tinyr vs 1.9 to see the cat kill part.

    change this.



    to this



    and change this




    to this



    save and rename the file, and your done.

    98 Buick Regal GS, F body brakes, Caddy STS wheels, tinted tails L36 bottom end, lightly ported heads, 1.95 roller rockers, headers, 2.8, FSIC, 42 lb injectors, a BrandonHall rebuilt trans, DHP tuned and AEM water/Meth injection https://goo.gl/gpV5kW

  19. #19
    SE Level Member Keko's Avatar
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    Default Re: Cat delete be too loud?

    You're the man. Thanks
    [Daily] 2002 GTP 40th Ann - FSIC, dp+plog, 3.3", ported LIM, HAI, front+rear sway bars, poly mounts, zzp tune for now :/
    [Fun] 2012 mazdaspeed3 - dp, 3" intake, FMIC, HPFP, Custom tune, lots of other goodies

  20. #20
    Killa Bee Scottydoggs's Avatar
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    Default Re: Cat delete be too loud?

    oh, and delete the rear o2 codes and the cat code if thats not done yet.

    98 Buick Regal GS, F body brakes, Caddy STS wheels, tinted tails L36 bottom end, lightly ported heads, 1.95 roller rockers, headers, 2.8, FSIC, 42 lb injectors, a BrandonHall rebuilt trans, DHP tuned and AEM water/Meth injection https://goo.gl/gpV5kW

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