355 - Code P1448 Every 50 Miles | FerrariChat

355 Code P1448 Every 50 Miles

Discussion in '348/355' started by sgtpeper, Jul 19, 2020.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, Skimlinks, and others.

  1. sgtpeper

    sgtpeper Formula Junior

    May 4, 2004
    420
    Denver
    Full Name:
    Jeff
    Since purchasing my '97 355GTS, I have put probably about 150ish miles on it. Code P1448 seems to come on about every 50 miles... I just clear it with a code reader and move on.

    Here are the clues for diagnosing this annoying issue - some I'm sure are related and some not.
    1. I have aftermarket cats but the exhaust is stock otherwise.
    2. I did have mini cats put on - o2 extenders to try to fix the issue when I first bought it.
    3. I have a Forza bypass valve controller - but I leave it on auto
    4. I think my bypass valves open late?
    5. On the highway, even on a hot day the water temp only seems to get to about 1/4 up the gauge. In traffic it sits right at about 190 though.

    What do you all think the issue is and how do I fix it? And don't say remove the bulb! I have to pass emissions tests every couple of years here.

    Another photo of the car all paint corrected and ceramic coated for attention.

    Thanks!
    Image Unavailable, Please Login
     
  2. Beetle

    Beetle Formula Junior

    Apr 10, 2013
    776
    Possible thermostat issues with those temps, mine moves down a little on the open Rd compared to in traffic.Thermostat fixed a lot of those codes in mine. Are your post cat sensor extenders 90 degree type. I kept getting codes until i went 90 degrees. Good luck
     
  3. Qavion

    Qavion F1 World Champ
    Silver Subscribed

    Feb 20, 2015
    11,484
    Sydney
    Full Name:
    Ian Riddell
    I assume Auto leaves the bypass management to the Motronic ECU? Does the Forza system use its own relay to switch between modes? Do you have a wiring diagram for the Forza system?

    I see your earlier post and the debate that ensued

    https://www.ferrarichat.com/forum/threads/bypass-valve-opening-late.623824/
     
  4. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    12,661
    San Carlos, CA
    Full Name:
    Mitchell Le
    Your Non-OEM bypass valve is causing this code. Want to get rid of it, then you have to get a stock OEM valve.
     
    Beetle likes this.
  5. drbob101

    drbob101 F1 Rookie
    Owner

    Nov 26, 2012
    3,814
    Tinton Falls, NJ
    Full Name:
    Bob Ferraris
    Get the constant voltage sdecu. Problem solved
     
  6. sgtpeper

    sgtpeper Formula Junior

    May 4, 2004
    420
    Denver
    Full Name:
    Jeff
  7. Ferrarium

    Ferrarium F1 Veteran
    Rossa Subscribed

    Jul 28, 2018
    5,624
    Central NJ
    Full Name:
    Eric
    348/355 and even 360 tend to run cool on the highway unless it's mid 90s temperature and humid even then it runs cooler. In traffic 190 is fan switch setting to kick on.
     
  8. drbob101

    drbob101 F1 Rookie
    Owner

    Nov 26, 2012
    3,814
    Tinton Falls, NJ
    Full Name:
    Bob Ferraris
    its a sdecu that sends out a constant voltage that satisfies the motronics that all is well at the bypass regardless of your set up and issues.

    wbt is a member here and makes them. Hopefully someone will chime in with where and how you get one. It replaces your oem sdecu for that location.
     
  9. malex

    malex Formula 3
    Silver Subscribed

    Dec 5, 2007
    1,245
    FL
    #9 malex, Jul 20, 2020
    Last edited: Jul 20, 2020
    I don't know anything about the Forza bypass control, other than guessing that in "auto" mode, it bypasses the aftermarket circuitry and defaults to the Ferrari controls. With that caveat . . . have you bench tested the catalyst control unit (CCU) for the bypass (Motronic 5.2 cars have a right, left, and bypass CCU), if for no other reason than to just eliminate it as an issue? It should produce ~0.5v when cold and over 2.0v once the thermocouple is heated up to a dark cherry red. Ratarossa on Youtube shows the procedure for testing. That said, it's pretty straightforward. And by CCU, I'm referring to location 42 per diagram in link below:

    https://www.ricambiamerica.com/car-diagrams/ferrari/v6-v8/355-group/f355-m5-2-1996/air-injection-device.html?mode=split

    I ask because I had a p1448 issue in the spring. It took a while to diagnose but wound up being a bad CCU. When I first tested my CCU, it passed the voltage/heat test above and I reinstalled it in my '97 355. No CEL for a while then after ~30 miles of driving, the car produced a CEL and a p1448 once I scanned for codes.

    I pulled the CCU back out of the car and bench tested it several more times. Only then did I realize that it was giving erratic signals (i.e. sometimes tested ok, other times odd voltage readings, other times no increase in voltage even with a hot thermocouple). A 1x test wasn't enough to find the fault. I had assumed that if the CCU failed, it'd be a binary outcome, i.e. either it did work, or not at all. This assumption, and my laziness in not testing for repeatability, caused avoidable frustration. So if you're going to test yours, then I'd recommend running the test 10x or so. If yours does test as bad, I'd recommend an aftermarket replacement, www.technistrada.com, rather than oem Ferrari. I replaced my black potting compound CCU (likely original to the car) with a Technistrada unit back in March. Problem solved as I've had no p1448 issues since.

    Fwiw, the bypass thermocouple tested ok. As a point of reference, my car has a new Capristo bypass valve, new Fabspeed cats and an older Tubi exhaust.
     
    Qavion and f355spider like this.
  10. Qavion

    Qavion F1 World Champ
    Silver Subscribed

    Feb 20, 2015
    11,484
    Sydney
    Full Name:
    Ian Riddell
    Has anyone actually tried a constant voltage SDECU in the bypass position? According to some, it shouldn't work in the bypass position as they say it needs to show a temperature/voltage change with the valve open.
     
  11. f355spider

    f355spider F1 World Champ
    Owner Rossa Subscribed

    May 29, 2001
    17,913
    USA
    Your thermostat is stuck open from your description of what the water temp gauge is reading. I had the same thing happen and a new thermostat returned it to normal. I would drive on the freeway and couldn't get any heat in the fall/winter when the gauge was constantly at 1/4. Once I pulled into traffic, it would be straight up at the 12 o'clock position and I could get some heat from the HVAC.

    As far as you P1448, you might try some diagnostic steps offered here:
    https://www.ferrarichat.com/forum/threads/p1448-obii-code.319195/
    P1448 is related to your bypass valve. Either it is not opening/closing properly, or the catalyst ECU or thermoprobe for the bypass valve are defective.
     
    ernie likes this.
  12. drbob101

    drbob101 F1 Rookie
    Owner

    Nov 26, 2012
    3,814
    Tinton Falls, NJ
    Full Name:
    Bob Ferraris
    Yes.

    skipr is one that I know has a constant voltage box installed with positive results.


    We don’t know what the main Ecu is looking for to be happy but it seems like it doesn’t want spikes indicating over heating. I have videos posted of the real time output at this location with no cel and the voltage varies from .8v at warmed up to 1.4v at BP valve open.

    It seems that a constant 1.5v satisfies the algo.

    I’ll let some who have used goths constant box or wcb new one respond as mine works fine as originally designed with OEM BP valve, big daddy mini cats and hi flow cats
     
    Qavion likes this.
  13. Skippr1999

    Skippr1999 F1 Rookie
    Silver Subscribed

    Dec 22, 2009
    4,212
    I went round and round with 1448 and as many here know, the Goth constant signal box was the solution. I have a capristo bypass and straight pipes. It’s a temperature thing. Get the box however you have to. It’s the only likely fix and bypasses a **** load of grief !
     
    drbob101 likes this.
  14. f355spider

    f355spider F1 World Champ
    Owner Rossa Subscribed

    May 29, 2001
    17,913
    USA
    In some cases, that might be. Both times I got the P1448, I was able to fix it. First time was a bad catalyst ECU. By swapping positions with the right side one, I found the issue. The other time, it was a bad Bosch Junior Timer connector to the solenoid. When I inspected the connector and pulled back the cracked rubber boot, it was filled with water, and one of the wires had come loose from the crimped metal connector. I took it apart and replaced the pin, and installed a new boot, and all good
     
  15. drbob101

    drbob101 F1 Rookie
    Owner

    Nov 26, 2012
    3,814
    Tinton Falls, NJ
    Full Name:
    Bob Ferraris
    This topic has been beat to death and that thread is old.

    In a OEM set up with perfect cats and no mods it will be ok if the sensing components work. Ie. SDECU and thermocouples.

    When cats are deleted or hi flow cats added or aftermarket mufflers or aftermarket BP valves or aftermarket BP valve controllers are added it becomes a mess.

    As I said, We don’t know what the motronics wants to be happy. I have tapped my outputs and I know what an output that doesn’t trigger a cel looks like but in vitro with mods it gets murky

    It seems that a constant voltage , maybe 1.5v, satisfies the motronics that all is well and thus no cel
     
  16. Skippr1999

    Skippr1999 F1 Rookie
    Silver Subscribed

    Dec 22, 2009
    4,212
    Wish Goth would share his design since he isn’t marketing these himself. I’m three years down the line with no further issues. It’s been very enjoyable....
     
  17. sgtpeper

    sgtpeper Formula Junior

    May 4, 2004
    420
    Denver
    Full Name:
    Jeff
    Where do I get this Goth box?
     
  18. Qavion

    Qavion F1 World Champ
    Silver Subscribed

    Feb 20, 2015
    11,484
    Sydney
    Full Name:
    Ian Riddell
    #18 Qavion, Jul 20, 2020
    Last edited: Jul 20, 2020
    As Skippr1999 says, it's no longer available.

    If you're looking for an available "constant voltage" (possible) solution, just fit Technistrada's plug.

    https://technistrada.com/355-360-456-550-575-f50-enzo/5-dummy-load-sdl-bypass.html

    For whatever reason, this comes with the warning:

    Not suitable for F355 bypass (3rd) centre ECU position. Only suitable for main positions (left and right) on F355 models.

    It may be because it doesn't give a warning if your bypass valve fails (The Goth Box, I assume, doesn't either)

    Technistrada's plug is also a useful diagnostic tool for the main cat temperature sensing system.
     
  19. Skippr1999

    Skippr1999 F1 Rookie
    Silver Subscribed

    Dec 22, 2009
    4,212
    Has anyone tried this product ?
     
  20. Qavion

    Qavion F1 World Champ
    Silver Subscribed

    Feb 20, 2015
    11,484
    Sydney
    Full Name:
    Ian Riddell
    #20 Qavion, Jul 21, 2020
    Last edited: Jul 21, 2020
    Do you mean in the bypass position?

    There is no doubt it works on the F355 in the main cat position, as does Technistrada's SDECUs. I made my own "dummy/no-cat/constant voltage" plug using identical components to Technistrada's when I had no cats (and it works). I'm not willing to test it in the bypass position however as I have a Goth's bypass valve and the valve hasn't exactly got a perfect reliability record.

    Having said that, you have to wonder how a normal SDECU even knows if a valve is broken if it's happy with a constant voltage.
     
  21. Beetle

    Beetle Formula Junior

    Apr 10, 2013
    776
    Mine has it Ian I made 3 off them. Never had a fault code with Cat system again. In saying that I put new temp probes in and mine had the green box ECU's that test perfect. Also have 90degree extenders and rebuilt CATs
     
  22. Qavion

    Qavion F1 World Champ
    Silver Subscribed

    Feb 20, 2015
    11,484
    Sydney
    Full Name:
    Ian Riddell
    Thanks, Paul. Is your system normal apart from the extenders?
     
  23. Badabing!

    Badabing! Formula Junior

    Mar 30, 2014
    731
    NYC
    Regarding temp concerns I suggest you get an OBD tool that is capable of reading PIDs so you can see what temp the ecu sees.

    The temp gauge in the dash is not accurate or reliable (in my experience) and the temp sensor for the ecu and the temp sender for the gauge are different.

    I use a Kiwi Wi-Fi 2 with the dash command ios app.

    Note I also have a Kiwi3 that for some reason has issues communicating with early OBD cars so I have to stick with the older version for the 355.

    They are up to version 4 and I do not know if they have resolved that issue.


    Sent from my iPhone using FerrariChat
     
  24. Beetle

    Beetle Formula Junior

    Apr 10, 2013
    776
    Yes mate
     
    Qavion likes this.
  25. pfbz

    pfbz Rookie

    Sep 25, 2009
    14
    Despite the CEL annoyance, your car looks amazing and drives wonderfully! Thanks!

    I'm no Ferrari guru, but the Technistrada SDL Bypass plug sounds like a good solution with perhaps a set of cat 'test' pipes to eliminate the small fire risk (can there ever be a "small" fire risk?).
     
    sgtpeper likes this.

Share This Page