p1448 OBII code | Page 3 | FerrariChat

p1448 OBII code

Discussion in '348/355' started by Labman, Apr 4, 2011.

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  1. PhilF355spider

    Jun 2, 2020
    12
    Full Name:
    Phil Wolejko
    The heat exchanger is new. Coolant is clean. Oil was fuming with gasoline. But as mentioned, after today’s cold start, new oil is in and no smoke with the exhaust disconnected.
     
  2. PhilF355spider

    Jun 2, 2020
    12
    Full Name:
    Phil Wolejko
    Not only the engine compartment, but after that first 30minute drive I took after rebuild, the leather seats and jeans I had on back then still smell of gasoline ;)
     
  3. malex

    malex Formula 3
    Silver Subscribed

    Dec 5, 2007
    1,245
    FL
    I should've mentioned that I had both p1448 and a SDL. Changing out two faulty CCUs and verifying all 3 thermocouples were functioning properly cured both problems since the one non-functioning CCU was for bypass.

    My right CCU gave inconsistent readings. When I first bench tested it (only once), it checked out fine and I reinstalled it in the car, along with the left bank CCU and the new Technistrada CCU (bypass). I cleared the codes. Started the car, went for a drive and both SDL and CEL were gone. Got home, scanned for codes - all good so far.

    So I took the car out again the next day for a longer ride with my wife. No SDL (since I had a properly functioning bypass CCU) but I did get a CEL. When I got home, I scanned again and saw the p1448 code.

    Up to that point, I "knew" (or so I thought) that I had 3 good CCUs, and 3 good thermocouples. I was confused (along with mumbling some choice words to myself) and decided to pull all CCUs and thermocouples for more bench testing (including checking the testing harness that I had made for continuity). At first, the right CCU tested fine (again). But during further rounds of testing, the right CCU then started delivering erroneous voltage readings (sometimes spot on, other times too low considering the thermocouple was glowing cherry). Solution was ordering a second CCU from Technistrada, which took a couple of weeks to arrive. Once I replaced the right CCU and cleared codes, it solved the p1448 problem (so far . . . crossing my fingers as I write this).
     
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  4. PhilF355spider

    Jun 2, 2020
    12
    Full Name:
    Phil Wolejko
    Thanks for your reply, malex, just to let you know, I was planning to take my wife out for a ride in the spider the next day...but unfortunately, it wouldn’t have been an enjoyable, smokey ride together, ha. Joke aside, did you have a rough running engine, smoke or other events, or just sdl, cel with no power loss?
     
  5. drbob101

    drbob101 F1 Rookie
    Owner

    Nov 26, 2012
    3,814
    Tinton Falls, NJ
    Full Name:
    Bob Ferraris
    Thr smoke and oil loss etc is unrelated to the sdl. The stl system shuts down a bank, period. It does not effect trim or anything else. It measures cat heat and protects the car by shutting down a hot bank.

    You will know when this happens as the engine is running on half power.
     
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  6. PhilF355spider

    Jun 2, 2020
    12
    Full Name:
    Phil Wolejko
    Thanks for your confirmation on this! And that’s what we are hoping for and now trying to check out. Would there be a possibility for the thermocouple (sorry, have been calling it a “thermoprobe”) to actually throw a signal to the ECU to change to rich mixture? Why would the car be spitting gasoline and smoking like a head gasket leak, but smelling like gas and burning crazy amounts of oil..??
     
  7. Ferrarium

    Ferrarium F1 Veteran
    Rossa Subscribed

    Jul 28, 2018
    5,624
    Central NJ
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    Eric
    No unrelated, it shuts the bank off when the cat gets hot, it does not adjust fuel, or air, or anything else, it shuts the bank off, that's it. Something seems off here.
     
  8. drbob101

    drbob101 F1 Rookie
    Owner

    Nov 26, 2012
    3,814
    Tinton Falls, NJ
    Full Name:
    Bob Ferraris
    Another point of fact.

    You’re getting a 1448 code which is a CEL from the bypass valve location. It is triggered by the SDECU and thermocouple there but As far as I know and the collective wisdom here, you don’t get a bank shutdown from this, just the CEL

    It is understood here as well that there is no mixture related compensation that takes place as a result of the 1448 code. Many have installed fake out circuitry for this SDECU location to get reid if the CEL, mostly in straight pipe and modified exhaust configurations that alter the exhaust flow and temps at the BP SDECU location triggering CEL 1448 annoyingly
     
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  9. malex

    malex Formula 3
    Silver Subscribed

    Dec 5, 2007
    1,245
    FL
    Just the latter. It ran fine even with the CEL and p1448 code. Once I got rid of the p1448 issue, I noticed no difference in how the car started, idled. performed etc.
     
  10. Carmellini

    Carmellini Formula Junior

    Jul 16, 2019
    814
    So, my 1448 code is a byproduct of installed Fabspeed bypass pipes and Nouvalari Sport muffler allowing more heat to migrate to the bypass TC probe?

    I have been chasing 1448 and swapped all three probes, all three TCUs, removed, cleaned and tested bypass valve and still after a reset, code comes back within 10 miles. The only thing I have not done is inspect and clean the connections at the solenoid valve, but with your anecdote, that won't matter.....??

    Originally, I had 11 valid codes that were all remedied with applicable solutions fairly easily. I really would like to get rid of the annoyance of 1448.

    There was a thread, by Gothspeed, where he states you can eliminate the code by capping off the probe fitting at the bypass valve and simply allow the probe to remain connected to the TCU, and let dangle in the wind. Sounds a bit too simple; can anyone confirm this?

    Does anyone make a dummy bypass unit specifically for the bypass valve TCU?
     
  11. drbob101

    drbob101 F1 Rookie
    Owner

    Nov 26, 2012
    3,814
    Tinton Falls, NJ
    Full Name:
    Bob Ferraris
    There is a guy in NZ who makes those. Maybe someone can post a link. He is on here as well
     
  12. Carmellini

    Carmellini Formula Junior

    Jul 16, 2019
    814
    Technastrada is the guy who makes bypass units for the main CATs, but not for the secondary. I think Goth made the secondary ones? anyone else?

    https://technistrada.com/

    I just tried the dangling probe test, and it does not work...LOL. Same amount of time for 1448 to come back. So is the TCU now seeing a temperature that is too low? A bit curious that the code is being trip in the same amount of time; I would have suspected some variance if plugged in it is too hot, and unplugged too cold? Could there be something I am overlooking?
     
  13. johnk...

    johnk... F1 World Champ
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    Jun 11, 2004
    10,629
    CT
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    John Kreskovsky
    Is you bypass valve working?
     
  14. Carmellini

    Carmellini Formula Junior

    Jul 16, 2019
    814
    yes, perfectly. I have taken it out, vacuum and visual test, smoke tested upon reinstall and works as it should. Seems 1448 is a bit common? for some.. or many...LOL There has got to be a way to resolve this?
     
  15. johnk...

    johnk... F1 World Champ
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    Jun 11, 2004
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    What I mean is are you sure it is working in the sense that it opens when the proper conditions are met.
     
  16. Carmellini

    Carmellini Formula Junior

    Jul 16, 2019
    814
    Valid question and best I can answer is yes, because I can hear the roar at higher RPM, but pretty sure that would not hold up in court....no way to place a camera for complete verification

    something is not making sense: I swapped all of the TCs, and the TCUs with no change. In addition, the problem did not move to the left or right TCUs. No SDL and no other CELs. So can we put the green TCUs and the probes in the rear view mirror? I think so. My bypass valve tests fine with no leaks, opens and closed smoothly, smoke tests show the area to be leak free, and I can hear and feel the power when the valve opens.

    Very confused about the dangling probe test. Can we determine for certain, that with the probe in proper position, is seeing higher than acceptable temps? The code is thrown after only a few miles, so nothing is really hot? Or, is the probe seeing lower thancceptable temps? Why did capping the bung and allowing the probe to hang result in nearly exact timing to throw the code?

    Could it be an improper vacuum routing issue? How can I determine if my vacuum connections are correct?
     
  17. johnk...

    johnk... F1 World Champ
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    Jun 11, 2004
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    John Kreskovsky
    I don't know exactly how the system works but common sense would say that since the ECU knows when to open the bypass it also knows when it should see a hot (open) or cold (closed) signal from the TCU. If you let it dangle then it would always see cold and thus the ECU thinks the bypass is not opening when you have throttle down and the RPM hits the required level. This would cause a cell. Also, if you have the TC correctly mounted and the bypass isn't opening it would also always see cold and you would get a (legitimate) cell. (Note: by "COLD" I mean below the threshold temperature the system expects when the bypass is open.)

    If the bypass seems mechanically ok perhaps you could check to see that the solenoid that controls the vacuum to the bypass is working.
     
  18. Carmellini

    Carmellini Formula Junior

    Jul 16, 2019
    814
    Agreed...this is my next plan of attack....... Tomorrow......Not exactly sure how to do that, but that is the final frontier?

    One unscientific thing to report; I pulled the connector at the secondary TCU, started the car and cleared the 1448 code. IMMEDIATELY, the code reappeared. Did this a few times. Next, reconnected the plug, cleared the code and it stayed cleared. This tells me the TCU is properly communicating with the ECU, and there is something "telling" the ECU to throw the code.

    Agreed, again............only reason I tried this is because I read a post where Goth said this would solve the issue. Made no sense
    on paper, and made no sense when it didn't work...LOL
     
  19. f355spider

    f355spider F1 World Champ
    Owner Rossa Subscribed

    May 29, 2001
    17,913
    USA
    I had the P1448 two times, one was a bad catalyst ECU (replaced) and the second time it was a bad wire to the solenoid that operated vacuum to the bypass valve. (wire came off the connector to the solenoid, I crimped a new pin on the connector).
     
  20. f355spider

    f355spider F1 World Champ
    Owner Rossa Subscribed

    May 29, 2001
    17,913
    USA
    I believe this is correct, the ECU is looking for the valve to correctly open and close, so it needs to see the proper high and low temps for confirmation.
     
  21. f355spider

    f355spider F1 World Champ
    Owner Rossa Subscribed

    May 29, 2001
    17,913
    USA
    #71 f355spider, Feb 18, 2021
    Last edited: Feb 18, 2021
    If swapping catalyst ECUs and thermoprobes is not eliminating the P1448. You need to definitely confirm the bypass is opening and closing properly. Get a buddy to mash the throttle so you can watch and confirm.

    If it isn't opening, check the vacuum hoses and the wiring and connector to the solenoid.

    If it is opening, then I would start checking your wiring specific to the thermoprobe and catalyst ECU to the bypass valve. Start with the connectors, pull back the boots and ensure the pins are good and clean. If those are good, you may need to trace from there back to the main ECU connector behind the passenger seat. You'll need the wiring schematic and check for continuity.

    Trying to spoof the motronic with a dummy isn't going to work if the wiring it bad. And you don;t want to spoof the motronic if indeed your bypass valve is not working.
     
  22. Carmellini

    Carmellini Formula Junior

    Jul 16, 2019
    814
    Another test that Goth suggests (i wish I could find the thread) is to disconnect the vacuum line to the valve. He stated this will eliminate the code; I guess because the probe will not see any low or high temp? He also says not to do this for an extended period of time.

    My thought is, if I remove vacuum and I still get 1448, then I can eliminate the valve and the probe? Would the solenoids still be in play?

    That would be nice, and easy

    I don't think lightening can strike 6 times?

    Since I know the bypass valve is in good repair, and if it sounds like its working, (lets assume its working) can it be a timing issue where it is opening and/or closing at a time the TCU does not like? back to vacuum and/or solenoids?
     
  23. johnk...

    johnk... F1 World Champ
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    Jun 11, 2004
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    Bottom line.

    1) The TC must be good.

    2) The TCU must be good.

    3) The bypass valve must be good.

    4) The solenoid must be good.

    5) The vacuum lines must be good.

    6) The wiring must be good.

    7) The main ECU must be sending the signal to open or close the bypass valve.

    8) The exhaust gasses must be hot enough to trip the high temp limit the ECU is looking for when the bypass is open.*

    *This last thing is just a thought because there may be a possibility that the exhaust gasses are further heated by the bypass cat and w/o the cat the temperature doesn't high enough. (Never heard this before but it just crossed my mind. Trying to think of every possibility.)
     
  24. Qavion

    Qavion F1 World Champ
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    Feb 20, 2015
    11,484
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    Ian Riddell
    The ECU can't read the solenoid position directly (only from the temperature), but I guess it may be able to check the continuity of the solenoid (55 ohms resistance)

    Why wouldn't it see low (with the valve permanently shut)?

    There are just too many varied/contrary opinions on what the ECU is looking for (high temps, low temps, delta temps). Some say a happy medium temperature will not trigger the message.

    Perhaps the logic is something like this:
    Low temperature is defined by a specific range. High is defined by a specific range, but there is a small overlap. A change from low to high range is required for "no fault", except in the small overlap range.

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  25. johnk...

    johnk... F1 World Champ
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    Jun 11, 2004
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    John Kreskovsky
    Again, common sense (and the WSM) says if the ECU is telling the valve to open it expects a voltage from the TCU greater then some threshold value (higher temperature). If the valve is supposed to be closed, less than the threshold voltage.

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    From hanging around here for many years I see people always trying to make things more complicated than they are.
     
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