Remote control bypass valves- reliable ones? CEL? Other issues? | FerrariChat

Remote control bypass valves- reliable ones? CEL? Other issues?

Discussion in '348/355' started by andrew911, May 22, 2015.

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  1. andrew911

    andrew911 F1 Rookie Silver Subscribed

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    I've read some discussion on remote vontrol bypass valves for the 355- I have two inquiries: (a) are there any that are reliable and are the complicated to install or not recommended? (B) will they cause CELs or other engine damage?

    There were a couple of interesting posts by BCWAWRIGHT in another thread (one of which is below)- when you use a remote control bypass valve to keep the valve open, is the system looking for a readout from the post-cat o2 sensor that won't be there if you were to drive with the bypass valve open for any length of time? I presume the system is OK getting no reading while the bypass valve is open, but does it eventually look for a reading? Maybe not if the car were driven on the autobahn for instance the bypass valve might be open the whole time at high speeds/high sustained throttle...but not sure if you opened the valve and drove the car a bunch in conditions where the computer would normally think the valve is closed...

    Here is one of the BEWAWRIGHT posts from another thread talking about high flow cats + CELs:
    "High Flow" cats are great for single exhaust system cars(almost all cars are like this).

    There is no need for this type of cat on a 355 which has two exhaust systems.....any regular cat that is properly sized will be sufficient....do not pay a premium for a "High Flow" type, that is a waste of money.

    Another interesting twist on the 355(5.2) which is not like most cars(especially of its era) is the post cat O2(lamba) sensor's output can be used by the ecm/ecu to adjust the fuel/air ratio......how that effects the engine when you remove it from the exhaust stream with extenders or remove and use a simulator I will leave it up to you to determine.

    As for sound?......you have the perfect set-up on the 355 for the personality of a "Dr. Jekyll and Mr. Hyde". The DR J side is all about the Stoichiometric Calculations for its' EPA master...a little on the tame side, but do a WOT or kick it past a certain rpm speed and it is no holds barred MR H that lets out an F1 scream all the way to the speed limiter. It doesn't get any better.

    So unlike the single exhaust systems where one puts on a "High Flow" cat to improve performance and then has to walk a thin line and do a balancing act to prevent CEL's, the 355 can use a regular cat that doesn't throw a CEL and when you need performance(top end) it just kicks it up to the secondary unrestricted exhaust system.

    Hope this gives you a better understanding of how your 355 works.
     
  2. andrew911

    andrew911 F1 Rookie Silver Subscribed

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  3. f355spider

    f355spider F1 World Champ Owner Rossa Subscribed

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    Rifledriver is completely correct. I had Ferrari of Seattle put a remote bypass switch in my 355 a few years back. My car was a 5.2 Motronic. They were able to spoof the Motronic to not throw a code for the valve being open all the time (there is a thermal sensor at the bypass valve to detect if the valve it open or closed to ensure it is working correctly) , that was not to difficult for them. But, they found Check Engine codes and fuel trim issues when the car is on bypass constantly. The problem is not enough exhaust is getting past the pre catalyst O2 sensors (pretty much everything goes through the bypass), messing with the fuel trims. After much testing it was determined this cannot be successfully done like on later cars (360, 430, 550, etc), unless the pre catalyst O2 sensors are moved further upstream, probably at he merge collector on the exhaust manifold, prior to exhaust splitting to the cats, and the central bypass valve. If you look at how the later cars exhaust is set up, all the exhaust goes through the catalysts prior to reaching the bypass valves. The 355 does not do this. So any 355, 2.7 or 5.2 will have fuel trim issues if the bypass valve is left open constantly. I would not recommend doing so.
     
    Last edited: May 22, 2015
  4. andrew911

    andrew911 F1 Rookie Silver Subscribed

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    Excellent and helpful post Hugh. Thank you
     
  5. tres55

    tres55 F1 Rookie Rossa Subscribed

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    It is to my understanding that using the remote bypass for short periods (couple of minutes at a time) will have no negative effect on the operation of the car.

    Please correct me if I'm wrong?
     
  6. andrew911

    andrew911 F1 Rookie Silver Subscribed

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    My guess is that is so Nindia- but I don't think I want to take the risk just given the unknown. I would imagine the amount of time may be for even more than a few minutes- heck this guy must have had the valve opened for about 15 minutes on the run in this video (although maybe no cats?) :) It's one of those things we're you would probably be OK with selective use a few-10-20 miles at a time sort of thing, but I'm just guessing..

    https://www.youtube.com/watch?v=Xs-G30Vv7ug
     
  7. f355spider

    f355spider F1 World Champ Owner Rossa Subscribed

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    It will set a "check engine" light pretty quickly on a 5.2 motronic car, as the thermo probe monitoring the bypass valve function will throw the code when it detects hot exhaust when it should be closed. It probably will not mess with your fuel trims too much in the short run...say a few miles...but I really wouldn't know for certain. Bottom line, not recommended.
     

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