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Thread: Need Help Troubleshooting...91 Spirit R/T

  1. #1
    Supporting Member II Turbo Mopar Contributor DOHCRT's Avatar
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    Need Help Troubleshooting...91 Spirit R/T

    Hey everyone, I have been messing with this thing for far to long and have hit a wall . The car has failed emissions numerous times, the last readings were: HC .92, CO 10.27 and NoX 2.75. It is currently failing for NoX by .25, but the other readings are just below the limits.

    Currently the car idles at 14.7 -15.1 which seems normal, but as soon as you touch the throttle, it goes dead lean for a second or 2 then swings to 9.5 - 10.5 and slowly makes its way back to 14.8. I tested the TPS and the voltage does not indicate a drop when the throttle is depressed, it acts like I expect. The plugs seem to indicate a rich mixture. While driving the wideband indicates 14.8 or so like normal, but when you lift off the throttle, it goes rich for a few seconds before it goes to fuel cut off.

    During my troubleshooting I have changed the following parts to verify what the OTC and wideband are telling me:
    Computer 2x
    TPS
    Throttle Body
    O2 Sensor (Mopar)
    Plugs (Autolite 65)
    Fuel Pump (confirmed bad initially)

    This car has not run since my ownership, I got it without a drivetrain. I installed a known good drivetrain and am observing the above problems.All systems are factory stock for now to aid in troubleshooting.
    Last edited by DOHCRT; 04-29-2019 at 05:02 PM.


    Vic in Phoenix
    dohcrt@cox.net

    91 Spirit R/T x4
    92 Spirit R/T x2
    89 CSX
    88 CSX-TIII
    84 Rampage TII
    97 Ram (Buzzin Half Dozen)
    69 Dart GT 'Vert

  2. #2
    Supporting Member II Turbo Mopar Contributor tryingbe's Avatar
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    Re: Need Help Troubleshooting...91 Spirit R/T

    Put in your VIN number and then print out the PDF of the entire emission dyno will really help as the things you noticed may or may not effect emission at all.

    http://65.82.88.69/AZDrvTce/rdPage.aspx?rdReport=TAGInq

    For example

    Click image for larger version. 

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  3. #3
    Supporting Member II Turbo Mopar Contributor DOHCRT's Avatar
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    Re: Need Help Troubleshooting...91 Spirit R/T



    Wow, I feel real stupid after that exercise. I guess I'm just used to modern day drag and drop photo attachments...
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    Vic in Phoenix
    dohcrt@cox.net

    91 Spirit R/T x4
    92 Spirit R/T x2
    89 CSX
    88 CSX-TIII
    84 Rampage TII
    97 Ram (Buzzin Half Dozen)
    69 Dart GT 'Vert

  4. #4
    Supporting Member II Turbo Mopar Contributor tryingbe's Avatar
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    Re: Need Help Troubleshooting...91 Spirit R/T

    I moved the NOX table up and combined the two pages.

    It looks to me the final acceleration from 26mph to 47mph at the 65 seconds to 80 seconds mark is what hurt your emission and it would appear your engine was running too rich judging from the HC level.

    It is very odd that all number went up at once.

    Any exhaust leak in front of the cat?
    How old is the cat?
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  5. #5
    Supporting Member II Turbo Mopar Contributor DOHCRT's Avatar
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    Re: Need Help Troubleshooting...91 Spirit R/T

    Brand new cat (2 years ago at the start of this ordeal, it was my first guess after the first failure), I checked for leaks and don't see anything obvious.


    Vic in Phoenix
    dohcrt@cox.net

    91 Spirit R/T x4
    92 Spirit R/T x2
    89 CSX
    88 CSX-TIII
    84 Rampage TII
    97 Ram (Buzzin Half Dozen)
    69 Dart GT 'Vert

  6. #6
    Supporting Member II Turbo Mopar Contributor tryingbe's Avatar
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    Re: Need Help Troubleshooting...91 Spirit R/T

    Quote Originally Posted by DOHCRT View Post
    Brand new cat (2 years ago at the start of this ordeal, it was my first guess after the first failure), I checked for leaks and don't see anything obvious.
    What brand is the cat?

    Stock ECU?

    Stock Injectors?

  7. #7
    Supporting Member II Turbo Mopar Contributor DOHCRT's Avatar
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    Re: Need Help Troubleshooting...91 Spirit R/T

    Walker? From Chris...Car is 100% stock


    Vic in Phoenix
    dohcrt@cox.net

    91 Spirit R/T x4
    92 Spirit R/T x2
    89 CSX
    88 CSX-TIII
    84 Rampage TII
    97 Ram (Buzzin Half Dozen)
    69 Dart GT 'Vert

  8. #8
    Supporting Member II Turbo Mopar Contributor DOHCRT's Avatar
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    Re: Need Help Troubleshooting...91 Spirit R/T

    One thing missing from the original post...Car knocks across all 4 cylinders at anything more than 5 psi, pulls equal amount of timing from each cylinder. Knock is audible, so not a bad sensor...


    Vic in Phoenix
    dohcrt@cox.net

    91 Spirit R/T x4
    92 Spirit R/T x2
    89 CSX
    88 CSX-TIII
    84 Rampage TII
    97 Ram (Buzzin Half Dozen)
    69 Dart GT 'Vert

  9. #9
    Supporting Member Turbo Mopar Contributor 2.216VTurbo's Avatar
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    Re: Need Help Troubleshooting...91 Spirit R/T

    I'm suspecting a faulty FPR, too high at idle, too low under boost, have you watched fuel pressure while driving? Also, is your airbox assembly all stock? Several TIII's have had that 90 degree inlet hose 'Suck shut' choking the motor under boost.

    AJ (no More Alan) 84 Rampage RT TIII/568 Quaife 87 GLHS dealer optioned Red 16V Masi/568/Quaife
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