Reprogramming 355 ECU to lower idle speed | FerrariChat

Reprogramming 355 ECU to lower idle speed

Discussion in 'Technical Q&A' started by ExcelsiorZ, Jun 25, 2008.

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  1. ExcelsiorZ

    ExcelsiorZ Formula 3
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    I drive my 355 spider daily (w/Tubi) and find the high idle and noise associated therewith to be annoying (e.g., when sitting at traffic lights, etc.) It's my understanding the idle speed is controlled by the ECU. Anyone suggest a good re-programmer of the ECU to set the idle at a more normal 750-800 rpms w/out charging a fortune? (Of course, this will also boost the infamously bad 9mpg epa city rating for the F355 as well.)
     
  2. tbakowsky

    tbakowsky F1 World Champ
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    The car was degined to idle at 1000rpm. Leave it alone. It has alot to do with the flat plain crank design and the over all internal dynamics of the engine.
     
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  3. maranello71

    maranello71 Formula 3

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    Don't do it! You'll foul up the engine with carbon deposits, resulting in bad idling and reduced performance. You'll also starve the engine of lubrication and cause a whole lot of vibrations that it isn't designed for. It was designed for 1000/1050 rpm, LEAVE IT if you don't want to end up with a big bill sometime in the future.

    Besides, what do you care of 9mpg in town? When do you ever drive a F355 in town? Town driving is for the Prius!
     
  4. TopElement

    TopElement Formula 3

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    Leave it alone. The lightweight engine internals, and clutch/trans setup, along with a few other things require a 1k idle. In a 355, I don't know how anyone could dislike it. Especially with an aftermarket exhaust!
     
  5. cf355

    cf355 F1 Rookie

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    #5 cf355, Jun 25, 2008
    Last edited: Jun 25, 2008
    When you installed the tubi did you remove the bypass valve and install a bypass pipe?

    If so, re- install the bypass valve and the drone you speak of will be gone.

    I have a race tubi (read louder than the standard tubi) and I re-installed the bypass valve and the car is quiet at idle,,,,,,almost as quiet as the stock exhaust. But on wide open throttle she sings.

    One further note.....if you lower your idle speed you will also lower your charging rate and run down your battery.
    Years ago I lowered my idle speed by 50 rpm on a vette and with in an hour of city driving killed the battery. I subsequently boosted the car and restored the stock idle speed and never had another charging issue with that car.
     
  6. 285ferrari

    285ferrari Two Time F1 World Champ
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    #6 285ferrari, Jun 25, 2008
    Last edited: Jun 25, 2008
    Even with a secondary cat bypass pipe--the bypass valve stays on.... The only way to get rid of it is to upgrade to the new Capristo system that does away with the stock bypass valve and replaces it with 2 exhaust bypass valves built into the exhaust....
     
  7. eulk328

    eulk328 F1 Rookie

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    Nobody knows better where the warm idle must be set than the manufacturer and you certainly are not going to improve gas mileage by any noticeable amount by setting idle 250 rpm lower. It the engine kept running at an idle of 750 rpm the only savings would be when you are completely stopped and it doesn't take a great deal of fuel to keep it idling. Throw in a couple of engine re-starts because of possible stalling and any tiny savings are out the window. Then you have the other factors that have already been mentioned regarding battery charging, vibration etc.
     
  8. ExcelsiorZ

    ExcelsiorZ Formula 3
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    Hmmm. Not sure I'm in agreement here. First note, I do still have my by pass valve and it does work as the system gets nice and loud under throttle. If anyone out there actually drives there F355 daily then I think they'll appreciate what I'm speaking of. They are loud buzz boxes at idle. This flat crank argument I'm not on board with either. I had a 308 (also flat crank) and one of it's two digiplexes went out. The flat crank motor runs as essentially two four cyl motors. With one entire bank of cylinders not firing she still idled smoothly, even if only at about 750 rpms. Loss of battery charge? Most alts don't really kick in much juice until above idle speeds. A few moments stopped here and there will make no difference to the battery. Lubrication? I doubt a 250 rpm change will affect the F355 at all. In fact, by modulating rpms with clutch down to 750 rpms I noticed no real oil pressure differential.
     
  9. cf355

    cf355 F1 Rookie

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    I think your incorrect in all your assumptions......but its your car and you may do as you wish.

    Good luck.

    p.s. a properly charging alternater at idle will pump out min 14 volts (for the 12 volt battery).......it is charging the battery. I suggest you purchase a digital meter and moniter the output.
     
  10. Samy

    Samy Formula Junior

    Dec 2, 2005
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    I also don't think that a lower idle rpm would harm anything. The main point on setting the idle rpm is the running behavior. And the starving when you go from full throttle suddenly to a complete closed throttle. Ecspecially if its cold. The more valve overleap and the longer the cam opening durations are the higher the rpm. That are the factors the flat crank shouldn't be a problem a more moderate 4 cyl. with 60-90 hp/l displacement would idle just fine with 780-850rpm when its warm. Thats the normal idle on stock cars with such a engine. The 355 engines has more hp/l displacement and more aggressiv cams wich needs more rpm idle otherwise it wouldn't sound healthy and you could get problems with starving. But i would try it because it won't harm the engine and only is a comfort point. To setup another idle rpm you only need to reprogramm the ecu(s) there is a map inside wich has the target rpms depending on the water temperature in it. I wouldn't lower the idle rpm's for the colder temperatures but lower the ones for normal / hot running conditions and give it a try if the engine isn't starving on how you drive everyone drives different. Also your idle would sound inconstant , inharmonic. If you can find someone in your area knowing how to reprogramm your ecu i would give it a try. Reprogramming takes only some minutes if its not good just revert it back.
     
  11. ExcelsiorZ

    ExcelsiorZ Formula 3
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    Thanks for the good advice. I will have only the hot temp idle speed lowered.
     
  12. lusso64

    lusso64 Formula 3

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    Rather than risk damage to the engine, get rid of the tubi! That is the cause of the problem. I too had a 355 with tubi and did not like that idle drone. I sold the car so didn't really need to ever address the issue.

    Of course, the folks that have already responded, some of whom are very experienced Ferrari mechanics (without boasting of this fact) have basically given you enough reasons not to. Of course, your car, your money.
     
  13. jm3

    jm3 F1 Rookie

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    Purely from memory, the idle is supposed to be 1050 rpm. I looked in my manual and can't find it.

    You have not mentioned what idle you are actually at right now. I have noticed that my idle creeps up during the Summer, because if I start the car with the A/C engaged, it bumps up the idle for the next time. The same when I drive with my fog lights and parking lights on (home made DRL for a low silver car in a world of Soccer Moms who cant see). Eventually my idle will be setting itself at 1150 or so, every time.

    The only way to get the idle back down is to reset via the disconnect battery routine, although if I remember to turn off the parking lights and A/C before starting the car, the idle will trend downward but it might take 10 days so I just disconnect the battery.


    FWIW,

    Jay
     
  14. Aircon

    Aircon Ten Time F1 World Champ
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    can you explain that further please?

    what's it got, and how does it operate?
     
  15. cf355

    cf355 F1 Rookie

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    #15 cf355, Jun 30, 2008
    Last edited: Jun 30, 2008
    The capristo does not utilize the upper y-pipe (cat) and bypass valve.

    This exhaust is classified as a race (off road) only exhaust as the former upper y-pipe (which houses 2 metallic catalytic converters) is removed and in its place are 2 straight pipes which exhaust directly out the back of the car. These upper pipes also DONOT go through the muffler either (hence is emission & noise illegal /why it is classified as a race/off road only exhaust) but have vacuum valves on each of these upper pipes that only allow the upper pipes to open once 2500 or so rpm is reached (which is all the time).

    Now of course people will use it on the road but having half the exhaust exiting through a straight pipe has to be seriously loud.....but for some this is the desire.

    Now in the post by 285 Ferrari, he mis-understood my prior post to which he was responding....I was not referring to the y-pipe when I mentioned the challenge bypass pipe......
    The challenge bypass pipe is simply a little pipe that is installed on the challenge cars. You in fact leave your factory y-pipe on the car and simply remove your bypass valve and install the challenge pipe in its place......thereby leaving the y-pipe to exhaust to the factory or aftermarket muffler all the time. No bypass valve to fail and your cats/manifolds ect run a little bit cooler and the car has a more powerfull sound.
     
  16. f355spider

    f355spider F1 World Champ
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    Is there any data to support that assumption?
     
  17. cf355

    cf355 F1 Rookie

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    #17 cf355, Jul 2, 2008
    Last edited: Jul 2, 2008
    1) with the bypass valve open all the time the exhaust is less restrictive as the exhaust is split through 2 sets of cats (the upper cats are LESS restrictive) so the manifolds will run cooler.
    I have noted personally on my 355 that with the bypass valve installed (WITH BRAND NEW FACTORY CATS) on the car that the cats have a blue hue on the front intake side of the cats. With the bypass valve removed, replaced by the challenge pipe the blue hue dissappears after a few strong runs and the cats return to the bronze colour. I could use a thermal scanner but its obvious that the blue colour identifies a much hotter cat.....and everything upstream (manifolds) are hotter as well as you can see more blue hue on the manifolds. It is normal to see the blue heat hue on portions of your manifolds because the stainless pipes in places are right next to the heat shielding.
    2) more powerfull sound? well all you have to do is temporarily wire open your bypass valve open and take the car for a drive.....your idle will have a much deeper drone and driving and w.o.t will be a much stronger sound (again the same sound when the stock bypass valve opens).

    If I decide to remove my bypass valve again I will use my thermal scanner and scan the manifolds and cats and provide this 'data' to the fellow chatters.
     
  18. Targatime

    Targatime Formula 3

    Feb 22, 2014
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    *old thread alert*

    Wondering if anyone has tried the OP's idea? If it was easy, and there was no downside, I wouldn't mind dropping the idle to 800-900. I find the stock idle RPM....busy, is I guess the word I'd use. Or frenetic. I don't buy the idea that you'd have low oil pressure or carbon buildup or battery charging problems (on 993's when you convert to an RS pulley, the alternator charges the battery more slowly at idle but this just isn't a real-world problem).

    I do buy the possibility that intake reversion caused by 355 cams may necessitate a higher idle (anyone know lift/duration/lobe separation specs?). I also would buy the possibility that Ferrari just made the idle 1050 rpm's as exotic car theater and it would do just as well at 850. Curious if anyone knows.
     
  19. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    You're solving a non-problem -- the idle speed is higher on a 355 vs a 350 small block chevy mostly because the stroke on a 355 is shorter (the maximum idle piston speed is about the same on both engines).
     
  20. ExcelsiorZ

    ExcelsiorZ Formula 3
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    I don't think that's the key data point. Fact is when the idle was 150 rpms or so lower the interior when stuck in traffic was a more comfortable/enjoyable place to be and less frenetic.
     
  21. Targatime

    Targatime Formula 3

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    I don't follow the logic here. My early 911 has a 66mm stroke (vs the 355's 77mm) and idles beautifully at 750rpm's.
     
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  22. windsock

    windsock Formula 3
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    My guess is your car is not running properly now. The 355 uses 8 individual throttle bodies that must be properly synched. If they are not you will get a lot of vibration. Another area I would consider is the camshaft timing. The 355 due to its high output per liter and the 5 valves per cylinder is extremely sensitive to even small inaccuracy's in cam timing. Balancing the throttle and comparing the amount of throttle opening per bank will give you an idea of the balance in the cam timing between banks. The last area I would focus on is the condition of the dual mass flywheel and the motor mounts. There is no reason this car wont run properly and smoothly.
     
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  23. ExcelsiorZ

    ExcelsiorZ Formula 3
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    No, that's not it at all. My point is this: A car like a 355 that idles high as the norm from the factory, as opposed to say 800 rpms at idle, is not as comfortable in daily regular stop and go LA traffic use. Frankly, it gets bit irritating if you drive the car daily. When the idle dropped in my car, albeit temporarily, to just 800 or so RPMs, it was a much nicer environment to be in.
     
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  24. Targatime

    Targatime Formula 3

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    This is exactly right. My car also runs beautifully, and like Excelsior I live in West LA and find the high idle annoying in traffic. Nothing more to it than that.
     
  25. tazandjan

    tazandjan Three Time F1 World Champ
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    Ferrari 4 cam engines do not generate a whole lot of vacuum at low revs, and that may be one of the reasons for the high idle. Could also be that the relatively crude Motronic 2.7 and 5.2 ECUs need a higher idle speed. When the 550 went from 5.2 to 7.1.1 with COP in the 575M, idle speed was lowered from 900-1000 rpm to 750-800 rpm.
     
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