Excess fuel in cat converter | FerrariChat

Excess fuel in cat converter

Discussion in '348/355' started by yelcab, May 21, 2018.

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  1. yelcab

    yelcab F1 World Champ
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    Mitchell Le
    #1 yelcab, May 21, 2018
    So, I have a couple of episodes now of my 1-4 right hand side stock cat converter on a 96 Spider glowing red. It happened first time six months ago and I put the car off the road for long term projects. Got it out of the garage a few weeks ago and drove it on a couple of drives without any incidents. Last weekend, the SDL came on and the cause was a glowing red cat converter. Which means, excess fuel is getting into the cat converter.

    So how many causes are there for excess fuel to end up there?

    1. Leaky fuel injectors (checked, they were sent out for rebuild)
    2. Running rich
    3. Failing fuel regulator resulting in hi fuel pressure
    4. Failing ignition wires (ohm resistance checked out, but that does not mean much)
    5. Failing spark plugs (They are new)
    6. MAF?
    7. Thermostat?
    8. Headers?
    9. ???
     
  2. INTMD8

    INTMD8 F1 Veteran
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    #2 INTMD8, May 21, 2018
    Cam timing?

    Don't think it would be a regulator or maf as that would affect both banks.

    Any difference in fuel trims from bank to bank? Codes?

    Could be plugs/wires but you would feel it misfiring.
     
  3. Wade

    Wade Three Time F1 World Champ
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    #3 Wade, May 21, 2018
    Or possibly a clog in the converter, thus restricting flow? Did it run okay otherwise e.g. no stumbling?
     
  4. Wade

    Wade Three Time F1 World Champ
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    #4 Wade, May 21, 2018
    9. O2 sensor
     
  5. SoCal1

    SoCal1 F1 Veteran
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    #5 SoCal1, May 21, 2018
    converters may be breaking up clogging, pull an 02 and have a look see before you do major damage
     
  6. yelcab

    yelcab F1 World Champ
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    #6 yelcab, May 21, 2018
    With your input, here is the game plan
    1. smoke test the exhaust for header leaks
    2. fuel pressure test at the rail for fuel regulator
    3. Inspect maybe change O2 sensor at the front
    4. remove / inspect cat converter
    5. inspect or change ignition wires
    6. Run, plug in real time OBD2 scanner and inspect LT / ST fuel trims left to right
    7. using OBD2 and hand-held laser thermometer to verify thermostat opening and coolant temp while running
     
  7. taz355

    taz355 F1 Veteran
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    #7 taz355, May 21, 2018
    I am with the group that thinks a plugged or likely partially plugged converter.

    This only because the obvious problems have new components that obviously worked for a while or until now.
     
  8. yelcab

    yelcab F1 World Champ
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    #8 yelcab, May 21, 2018
    Yes, but what would it be plugged with?
     
  9. Wade

    Wade Three Time F1 World Champ
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    #9 Wade, May 21, 2018
    Running too rich for too long and the internals melt, eventually clogging the converter.

    Lots of examples of Google.
     
  10. fatbillybob

    fatbillybob Two Time F1 World Champ
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    #10 fatbillybob, May 21, 2018
    It's bad Karma. You brought panzer to stoogefest. 355 is pissed off. Don't screw with Italian mistress.
     
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  11. taz355

    taz355 F1 Veteran
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    #11 taz355, May 21, 2018
    When I say plugged I mean restricked a lot, some chuncks of ceramic broke and are lodged sideways restricting flow, maybe meltd as stated above.
     
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  12. yelcab

    yelcab F1 World Champ
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    #12 yelcab, May 21, 2018
    . But that started with the running too rich ... not with the cat converter melting.
     
  13. Wade

    Wade Three Time F1 World Champ
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    #13 Wade, May 22, 2018
    Wouldn't you love to put pressure sensors in both sides of the exhaust system, upstream of the cats? The alternative is a visual, internal inspection. If good, I'd switch sides with the MAFs. But do a temperature reading before and after.
     
  14. SoCal1

    SoCal1 F1 Veteran
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    #14 SoCal1, May 22, 2018

    Yeuuup thats most common with them for sure, first the cats glow then bye bye headers :)
     
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  15. johnk...

    johnk... F1 World Champ
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    #15 johnk..., May 22, 2018
    Last edited: May 22, 2018
  16. Wade

    Wade Three Time F1 World Champ
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    #16 Wade, May 22, 2018
    Any updates? I was hoping you'd give us some pointers.
     
  17. yelcab

    yelcab F1 World Champ
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    #17 yelcab, May 23, 2018
    I have not made any progress due to other priorities, but I will start this debug soon. Will update as I go.
     
  18. SoCal1

    SoCal1 F1 Veteran
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    #18 SoCal1, May 23, 2018

    Now thats a "classic' ferrari 355 picture :)
     
  19. Wade

    Wade Three Time F1 World Champ
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    #19 Wade, May 23, 2018
    Yeah, should have been wearing my glasses, for some reason I thought you had a 348 Spider.

    Still, I'm interested in what you find.
     
  20. 8500rpm

    8500rpm Formula Junior

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    #20 8500rpm, May 23, 2018
    Running rich, wouldn't that cause black exhaust?

    I'm with the damaged catalyst crowd (you run Hyper Flow?), but looking forward to the diagnosis.
     
  21. yelcab

    yelcab F1 World Champ
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    #21 yelcab, May 24, 2018
    OK update.

    Fuel pressure is 55psi, on spec.
    No exhaust leaks from the smoke test.
    There is some intake vacuum leak at the sound resonator box. I still have that big ugly box. I need to change to a plug. Does anyone know what that replacement plug is called and where it is sold?
     
  22. taz355

    taz355 F1 Veteran
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    #22 taz355, May 24, 2018
  23. spider348

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    #23 spider348, May 25, 2018
    Same issue with my F355 years ago. #7 plug wire in my case. Replaced with a complete set of Kingsborn? wires. Resistance checked fine for all. No misfire noted. Wire had not completely failed, fired then random failure. Low cost fix if that is the issue. Good Luck!
     
  24. yelcab

    yelcab F1 World Champ
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    #24 yelcab, Jun 7, 2018
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  25. emac

    emac Formula Junior
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    #25 emac, Jun 7, 2018
    have you pulled any codes or checked fuel trim #'s?
     
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