Results 1 to 12 of 12

Thread: Converter bad? need help on diagnosis!

  1. 03-09-2012 #1
    Jochen
    Jochen is offline
    Tuner in Training
    Join Date
    Sep 2004
    Location
    Munich Germany
    Posts
    48

    Converter bad? need help on diagnosis!

    Good morning!

    Really hope somebody can help me on this one:

    A while ago i had a bad missfire on my 07 Escalade, followed by a flashing MIL. Searching the problem i found two badly dammaged spark plug wires. Guess some martens were hungry...

    A few days later i got a permanent MIL with DTC P0420, pointing to catalytic converter problems... even more

    I replaced the wires, deleted the DTC, but it came back a few days later (after the ECU ran all the tests a few times to find out something isn´t right)

    I think the missfire lead to too much fuel in the converters, destroying one or both of them, giving me the P0420.

    Does anybody has an idea how to use HPTuners to find out if one of the converters is bad? What PID´s would be best to use (i guess all O2 Sensors should be scanned...) and what i have to expect to see if something is wrong with a cat?

    ANY help is highly appreciated!

    Thanks and have a nice days!

    Jochen
    Reply With Quote Reply With Quote
  2. 03-09-2012 #2
    realcanuk
    realcanuk is offline
    Advanced Tuner
    Join Date
    Jun 2011
    Location
    Montreal, Canada
    Posts
    758
    ALthough codes and symptoms can point you to the converter, the only way to really know for sure is to disconnect the pipe and take a look.

    Ask me how I know.......

    2007 Corvette C6 Vert. A6
    LME LS402, Pat G custom cam, ATI 10% OD Damper
    Circle D triple disc 2600, 3.42 Diff
    YSI, 3.0 pulley, ID 1000's
    Alky Control Meth,
    ARH 1 7/8 headers,
    1009 RWHP @ 7000, 817 RWT @ 6000
    Reply With Quote Reply With Quote
  3. 03-10-2012 #3
    Jochen
    Jochen is offline
    Tuner in Training
    Join Date
    Sep 2004
    Location
    Munich Germany
    Posts
    48
    Wow.... what did you do? Dropped a granade in it?

    Well, today i scanned parameters from which i think might be important to emissions and O2 Sensors and could help on finding the fault...

    On the pictures you can see data from all four O2 Sensors and Cat temperatures. The first screenshot looks OK. Its taken during the engine was still cold, during warming up. No big difference on what the four sensors are showing, cat temp. is similar.

    The second picture is a different story, and that is how the data looked for about 90% of the scanning time! On Bank 2 sensor No. 2 reads most of the time a value around 750mV, while Sensor No. 2 on Bank 1 is still variable between approx. 60 and 800mV.

    According the P0420 a problem occured on Bank 1 in the system. Does that mean the steady readout of 750mV from Sensor 2 on Bank 2 is normal, while Sensor 2 on bank 1 should not change that much?
    The Sensors should be OK as all data were normal during warm up cycle...

    Can somebody help on diagnosis?

    Many thanks!!!

    Jochen
    Last edited by Jochen; 03-10-2012 at 08:28 AM.
    Reply With Quote Reply With Quote
  4. 03-10-2012 #4
    realcanuk
    realcanuk is offline
    Advanced Tuner
    Join Date
    Jun 2011
    Location
    Montreal, Canada
    Posts
    758
    I can not help with your diagonosis from that data. That happened to my cats after a wiring problem caused some missfiring. I assume excess fuel did it.
    2007 Corvette C6 Vert. A6
    LME LS402, Pat G custom cam, ATI 10% OD Damper
    Circle D triple disc 2600, 3.42 Diff
    YSI, 3.0 pulley, ID 1000's
    Alky Control Meth,
    ARH 1 7/8 headers,
    1009 RWHP @ 7000, 817 RWT @ 6000
    Reply With Quote Reply With Quote
  5. 03-10-2012 #5
    Jochen
    Jochen is offline
    Tuner in Training
    Join Date
    Sep 2004
    Location
    Munich Germany
    Posts
    48
    Thank you!

    I did some research... As far as i could find out: The Sensor No.2 should show asimilar curve as the Sensor No.1 on that bank.



    Anymore ideas?
    Reply With Quote Reply With Quote
  6. 03-10-2012 #6
    carlrx7
    carlrx7 is offline
    Advanced Tuner
    Join Date
    Jun 2008
    Location
    Charleston, SC
    Posts
    969
    switch the sensors around. i have an some cats and sensors i can send you from my 06 ls2 vette, but shipping isnt going to be pretty
    Reply With Quote Reply With Quote
  7. 03-10-2012 #7
    Russ K
    Russ K is offline
    Senior Tuner Russ K's Avatar
    Join Date
    Dec 2005
    Location
    Regina, Sask.
    Posts
    4,214
    A bad cat will cause the rear O2 sensor to oscillate like a front O2. As you can see your bad cat's Bank 1 Sensor 2 graph is the same as the front O2's. And the graph of Bank 2 Sensor 2 oscillates less or not at all.

    Also if you don't have any rear O2 codes, P0420 is always the driver's cat.

    Russ Kemp
    Reply With Quote Reply With Quote
  8. 03-10-2012 #8
    flame
    flame is offline
    Advanced Tuner
    Join Date
    Apr 2009
    Posts
    613
    The bank 1 cat is not doing anything hence the B1S1 and B1S2 readings being almost identical. The rear sensor should be fairly constant like the B2S2 is showing. The cat temp is pcm calculated so it is no indication of function.
    1997 Trans Am WS6 - LS1 swap - TR224 - Pacesetter Longtubes - Yank SS3600
    - 3.42 Moser 12 bolt - Wilwood Brakes - HP Tuners tuned - P1SC-1 Procharger
    Reply With Quote Reply With Quote
  9. 03-12-2012 #9
    Jochen
    Jochen is offline
    Tuner in Training
    Join Date
    Sep 2004
    Location
    Munich Germany
    Posts
    48
    Thank you for your help. Well, looks like i need a new converter...
    Reply With Quote Reply With Quote
  10. 03-12-2012 #10
    Jochen
    Jochen is offline
    Tuner in Training
    Join Date
    Sep 2004
    Location
    Munich Germany
    Posts
    48
    Should i stay with the OEM Cat System or can someone recommend a weld in type universal catalytic converter? I did some pipe welding before and i guess i might save a couple hundred bucks by just exchanging the catalists....

    What would be the right size catalytic converter for that truck?

    Best regards,

    Jochen
    Reply With Quote Reply With Quote
  11. 03-12-2012 #11
    IDRIVEAG8GT
    IDRIVEAG8GT is offline
    Senior Tuner IDRIVEAG8GT's Avatar
    Join Date
    Aug 2010
    Location
    Roswell, N.M.
    Posts
    1,956
    Quote Originally Posted by Jochen View Post
    Should i stay with the OEM Cat System or can someone recommend a weld in type universal catalytic converter? I did some pipe welding before and i guess i might save a couple hundred bucks by just exchanging the catalists....

    What would be the right size catalytic converter for that truck?

    Best regards,

    Jochen
    You would have to adapt them but I am extremely partial to SOLO Performance Hi-Flow Cats.

    There are some other good ones too.
    Gray Ghost- The abomination. 2007 Chevrolet Silverado CCSB. 98mm turbo, nitrous, 428LSX, Rossler 80E with a brake. Finally finished. 23 psi, no numbers, Slow as hell.

    PBM G8- Aluminum 364, twin Precision 67/66 turbos, 6L90 trans swap, CTS-V/Vaporworx fuel system, slowly making progress.

    Dads 2011 CTS-V- Stock bottom end, stock heads, LS9 cam, pullies, ported blower, ported TB, D3 goodies, and lots of nitrous.
    618/618 motor
    906/862 spray

    Caterpillar 50 Forklift- Duramax swap
    Reply With Quote Reply With Quote
  12. 03-13-2012 #12
    Jochen
    Jochen is offline
    Tuner in Training
    Join Date
    Sep 2004
    Location
    Munich Germany
    Posts
    48
    Thanks!

    I just had a look at the pipe/converter section. The diameter of the OEM style pipe is approx. 2.5 inches. One converter has straight in/straight out pipes - easy to work with an aftermarket cat. However, the other site pipe enters the cat at an angle and the cat itself has a big dent to accomodate the not straight in pipe... so a bit more difficult to get a "straight design" cat welded in correctly...
    Reply With Quote Reply With Quote
« Previous Thread | Next Thread »