News

355 By Pass Valve + Check Engine Light?

Discussion in 'Technical Q&A' started by FL 355, Aug 23, 2004.

  1. FL 355

    FL 355 Formula 3

    Nov 3, 2002
    1,665
    Ft Laud
    Full Name:
    Frank Lipinski
    I've been following the threads on wiring open the by pass valve.

    Did it last week and it triggered the check engine light. Just got the car back from Shelton today (for new airbag cover) and the tech removed the code.

    SD-1 Exhaust Bypass Temp Light due to by pass valve being wired open.

    Question: When you wire open the by pass are you elevating or reducing the exhaust temp? I think it lowers it, and the OBD is looking for a higher temp. Does anyone know for certain?
     
  2. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
    26,949
    Austin TX
    Full Name:
    Brian Crall

    The OBD is just using exhaust temp at the valve to determine if the valve is open or closed to monitor it's correct function. There is an ex temp probe used just for that purpose and has no other function.
     
  3. FL 355

    FL 355 Formula 3

    Nov 3, 2002
    1,665
    Ft Laud
    Full Name:
    Frank Lipinski
    Thank you Rifledriver!

    Makes sense. Someone posted that if you leave it open the temp drops and your cats wear out sooner than normal.

    The cats are not an issue for me as I'm upgrading the headers and going with a straight pipe instead...

    Thanks again.
     
  4. speeder37

    speeder37 Karting

    Nov 18, 2003
    91
    Chicago
    Full Name:
    Matt
    A couple of questions.
    1. My 355 begins rattling at startup and calms down as the engine warms. Does this sound like the notorius bypass valve?
    2. The car has a Tubi. When throttle is applied the exhaust sound grows noticeably louder. This evening, when applying throttle, the exhaust note would sometimes remain subdued. Will the valve sometimes not open at all?
    3. Will wiring the bypass valve open cease the rattling?
    4. Is the valve covered under the emissions warranty?
    Thanks,
    Speeder
     
  5. FL 355

    FL 355 Formula 3

    Nov 3, 2002
    1,665
    Ft Laud
    Full Name:
    Frank Lipinski
    Yes, by pass valve will "rattle" at cold start and go away after warm up. This is normal.

    When you accelerate and get over 3K rpm (depending on gear) you normally hear the sweet "Howl" or "bark" of the exhaust. That comes from the by pass opening. What you describe (no sound) means the by pass is stuck in the closed position.

    Do a search on this forum. The cause could be bad valve, vacum line to the valve, or vacum pump. Sometimes just moving it open and shut by hand will "free it up" - you can do this with a bent coat hanger. You can also blow into the vacum line to see it it opens up.

    Many here have wired open the valve to have the sound all the time and to reduce back pressure. I even checked with Shelton and they said it does no harm, other than a check engine light if your car is 96 or newer.

    I would do something with your car rather quickly or keep the revs under 3K because running with valve closed could turn out to be problematic.

    If you want to wire it open, it takes 10 minutes and PM me and I'll send you photos and instructions.

    Also - If your like me, I can't drive my car with a check engine light on - drives me crazy, so I figured out a way to "hide" the light.

    I really like the way the car sounds and drives since I wired the valve open. If I ever want to return to the "normal" operation, all I have to do is snip the wire.
     
  6. pino

    pino Karting

    Nov 1, 2003
    208
    South Central PA



    Electrical tape? Bulb removal?

    Do tell how you "hide" the light.


    Bothers me also.

    Best,
    Pino
     
  7. richard_wallace

    richard_wallace Formula 3
    Rossa Subscribed

    Feb 6, 2004
    1,950
    Cincinnati, Ohio
    Full Name:
    Richard Wallace
    FWIW - you can in about 3 minutes remove the bulb... 2 screws on the consel - remove toward the drivers door - snap out the bulb - save it to put it back in later - all done...

    I think I had a thread out there on how to do this... I took out my Airbag light -I had a fault and had a few months before my oilchange, checkup - where they could reset it... But it drove me nuts seeing it on.. So I took it out and recently put it back in since I had it reset...
     
  8. Merdav

    Merdav Formula Junior

    Apr 11, 2004
    971
    Avtually the by pass valve has a threaded adjustment on it (Usueally rusted) the adjustment must keep it tightly closed at idle, if it is open even a fraction it will rattle.
     
  9. f355spider

    f355spider F1 World Champ
    Rossa Subscribed Owner

    May 29, 2001
    17,058
    USA
    Full Name:
    Hugh G. Rection
  10. MITengineer

    MITengineer Karting

    Feb 18, 2004
    178
    Laguna Beach, CA
    You lose low end torque, and ultimately acceleration by wiring the valve open.
     
  11. speeder37

    speeder37 Karting

    Nov 18, 2003
    91
    Chicago
    Full Name:
    Matt
    I drove the 355 probably 150 miles today with valve wired open. No noticeable loss of power. The sound combined with the Tubi is great. The sound at idle is a drastic improvement. The Check Engine light did come on after a bit. At the end of the day, this is a nice improvement.
     
  12. FL 355

    FL 355 Formula 3

    Nov 3, 2002
    1,665
    Ft Laud
    Full Name:
    Frank Lipinski
    A total non-issue and many threads on this. I de-cated and free flowed an exhaust on my PTurbo and, yes, did notice loss of bottom end.

    On the FCar I really could not tell or feel any loss. Additionally, FCars are not street racers from a standing start. I never run it hard from a dead stop. Once you get rolling and run up to redline, each up shift keeps the tach in the upper rpm powerband, so you never are in the lower torque curve...therefore, any potential loss of torque in lower range is a moot point IMHO.

    Put a lot of miles on her this weekend and the sound is sweet music - she also seems to breath better...at idle and lower rpm it feels like you took a load off the engine. Very pleased with the results.
     
  13. matkat

    matkat Formula 3

    Mar 18, 2003
    1,840
    Scotland
    Full Name:
    Dave McGuire
    Frank could You post the pics please,if they are to large could you PM them to me?
    Thganks
    Dave Mc
     
  14. SCarFan

    SCarFan Rookie

    Sep 22, 2004
    28
    Las Vegas, NV
    Full Name:
    Carlton Geer
    By "Hiding" the check engine light, you suggest removing the bulb. Does any one know how to reset the faulty light without an SD (at home) or without removing the bulb or taking it in for service? This light is a nuisance and does drive me crazy so your help is appreciated...
     
  15. FL 355

    FL 355 Formula 3

    Nov 3, 2002
    1,665
    Ft Laud
    Full Name:
    Frank Lipinski
    CGear...

    What I did originally was pull the panel. Look at the light cluster and you will see that it snaps into place. A small knief will pry it open, then remove by hand. A piece elec tape fits perfectly from the inside, snap back in.

    I latter went to the dealer and they programed the computer to ignore signals for by pass temp - that way light is operational in case something else triggers it. Cost was 1 hour labor.

    Unfortunately, you can not do it at home. Turning off the battery and recycling the sytem will still keep it in memory.

    Is your light from the by pass or is there something else?
     
  16. SCarFan

    SCarFan Rookie

    Sep 22, 2004
    28
    Las Vegas, NV
    Full Name:
    Carlton Geer
    The check engine light came on about 6 weeks ago. I took it in for service and it indicated that one oof the smog blowers was not working (which I can hear so I know it was a false reading).

    The check engine light came on again 2 days ago. I have not altered the by pass valve or any other emmission item from stock.

    The check engine light is, I believe, giving occasional false signals, and, although I don't want to bypass it in case it signals an actual problem, I hate looking at it. (By the way, I gassed up the night before the light came on so I've tightened the gas cap, etc. - ridiculous!)

    After reading a few of these technical comments, I've determined my best approach may be to buy an Innova # 3100 and read and reset the signal myself. Unless someone else has a better idea...
     
  17. FL 355

    FL 355 Formula 3

    Nov 3, 2002
    1,665
    Ft Laud
    Full Name:
    Frank Lipinski
    That's a hard call... I would have it checked one more time to see if its the same fault reading before buying the 3100. Connectors are notorius for bad connections and some cleaning with stabilant might do the trick. I would also reset the system with a power shut off and the 10 minute power up procedure. If you continue to get the same false signal over and overe again and can't find the cause, you could always have the dealer program the unit to ignore the smog pump signal, as they did with my by pass signal.
     
  18. SCarFan

    SCarFan Rookie

    Sep 22, 2004
    28
    Las Vegas, NV
    Full Name:
    Carlton Geer
  19. SCarFan

    SCarFan Rookie

    Sep 22, 2004
    28
    Las Vegas, NV
    Full Name:
    Carlton Geer
    Thanks for the advice. Your comments make sense as I do want to know if there is a real problem; however, I just bought an Innova (it was hard to find) and I'll probably keep a log of the readings as I erase the code. I'll have a ferrari mechanic review the log for problems. I feel confident this is a false fault and I can't stand to see the CE light.

    The car is running beautifully and I was just thinking the night before this light came on that it had been a while without this kind of annoying nonsense interrupting the pleasure. I use my 355 B F1 as a daily driver and expect service issues. But these lights are distracting ...
     
  20. FL 355

    FL 355 Formula 3

    Nov 3, 2002
    1,665
    Ft Laud
    Full Name:
    Frank Lipinski
    Good Idea... I'd just pull the bulb then... Likewise, I know my car well and know if something is not right....your log is a good idea. The only thing that may start going bad without warning to the driver is the cats, in that case you would get the "slow down" light instead.
     
  21. SCarFan

    SCarFan Rookie

    Sep 22, 2004
    28
    Las Vegas, NV
    Full Name:
    Carlton Geer
    For those who don't know, the cats are warranteed for eight years. The passenger side cat was replaced for free earlier this year on my car (a '98 355B).

    Thanks for all the help and advice..
     

Share This Page