2005 575M HGTC Exhaust - Ferrari Life
 
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post #1 of 17 Old 04-21-2013, 02:03 PM Thread Starter
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2005 575M HGTC Exhaust

Is it normal for the exhaust bypass valve to remain closed at idle and with revving the engine (car stationary)? Could I have a vacuum leak if the valve is not opening?

Vafa
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post #2 of 17 Old 04-21-2013, 04:29 PM
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Quote:
Originally Posted by Vmansouri View Post
Is it normal for the exhaust bypass valve to remain closed at idle and with revving the engine (car stationary)? Could I have a vacuum leak if the valve is not opening?

Vafa
Vafa, don't think you have a vacuum leak. Below is an quote from one of Taz's previous post in regards to when the bypass valves open on the 575.

"The 575s have a more sophisticated schedule, probably a result of the 575's more advanced 7.1.1 DME. Idling at ~ 750 rpm vs the 550's ~1000 rpm, the 575 valves are open at idle for a nice stoplight burble, close at 1000 rpm, and reopen at 2720 rpm and 64% throttle. Opening varies with rpm and throttle setting for the 575s, so lower throttle settings will result in the valves opening at higher rpm and WOT will result in them opening at 2720 rpm (as if anything was that precise)."

We later (after this post) determined that the bypass valves on 575's do not open at start up. It seems to me that you can stand behind the car and see them open with a good throttle rev but not absolutely positive. Perhaps someone can offer opinion or check this. Would do so but mine are bypassed to open at all times.
If you still don't see them open would suggest you try the bypass instructions previously posted and swap those two vacuum lines at the rear of the car. If they still don't open then I would look at the vacuum line forward of the switch (also located at the rear of the car) up to the engine compartment and make sure that it is connected to a vacuum source.
Post back here or by PM if these check out.
Also, if you have aftermarket straight pipes or x-pipes, a HGTC exhaust may be too loud with bypass valves left open. Either way you want to be sure that these valves are opening, power and sound would be missed.
Bill
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post #3 of 17 Old 04-21-2013, 04:33 PM Thread Starter
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I am suspicious mine are not opening as my exhaust note never really changes.

Vafa
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post #4 of 17 Old 04-21-2013, 04:47 PM
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There is not a point on these cars when it's obviously noticeable that they have popped open. At least not noticeable like some GM muscle using similar valves.
With the valves bypassed open from the beginning (regular exhaust or hgtc), it changes the rev range experience most in the lower rev range.
Another option may be to have someone follow you, that can keep up for a while, and have them watch for opening.
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post #5 of 17 Old 04-21-2013, 05:11 PM Thread Starter
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That would require serious tailgating!
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post #6 of 17 Old 04-21-2013, 05:50 PM
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Quote:
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That would require serious tailgating!



Next time you're on the highway, maintain highway speed in 5th gear. Then floor the gas pedal. If your valves are working, you should hear a change in the exhaust note when you do that.

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post #7 of 17 Old 04-21-2013, 08:14 PM
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575 Valves Are Closed at Idle

Vafa- That was a mistake I made and corrected in later posts somewhere. The 575M valves are closed at idle. The quote in the workshop manual had the idle confused with the 550, which idles around 1000 rpm, vs 800 rpm for the 575. The valves have a fairly sophisticated schedule, but to test, you need a minimum of 2620 rpm and 64% throttle. Higher rpm and lower throttle settings will also open the valves.

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post #8 of 17 Old 04-22-2013, 03:48 AM
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Hi Vafa,
on my 575 HGTC the bypass open approx. at 3000 rpm and gas pedal over 40/50 %, but the sound difference from inside cockpit is not big, you can try in following mode, you open little bit an glass door and in 4 o 5 gear from 2500 rpm you push gas over 70% , around 3000 rpm you should hear the sound change.
Instead with the car stop and gear idle, you must fully push gas pedal in fast mode and in the same time another person see the valve from the back side,I do so and they open.
A short i will put a button to open/close bypass when I want.

In every case the sound of HGTC system is not high ringing, but low-pitched ringing, and full of burble from outside car, inside the noise level is low.
Now i'm studing a modify (not invasive because I want to conserve this rare car) to obtain a sound much ringing ....
I will inform you about my progress ....

Fabio

PRESENT: 575 F1 HGTC ROSSO CORSA 2004' - MB CLS 350 CGI 2007'
PAST: 550 ROSSO CORSA 1998' - MB CLK 240 2002'
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post #9 of 17 Old 04-22-2013, 05:12 AM Thread Starter
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I put my camera phone behind the exhaust and recorded video as I revved the engine and the valve never opened. I tried uploading videos but get error message from FerrariLife server.
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post #10 of 17 Old 04-22-2013, 06:05 AM
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Vafa,
bypass open only if gas pedal is pushed over approx. 40/50 %, if you push soft and rpm engine go up, not important the rpm, the bypass not open ....

Fabio

PRESENT: 575 F1 HGTC ROSSO CORSA 2004' - MB CLS 350 CGI 2007'
PAST: 550 ROSSO CORSA 1998' - MB CLK 240 2002'
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post #11 of 17 Old 04-22-2013, 07:54 AM
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Quote:
Originally Posted by Vmansouri View Post
I put my camera phone behind the exhaust and recorded video as I revved the engine and the valve never opened. I tried uploading videos but get error message from FerrariLife server.
Vman, at this point you are going to need to see if your vacuum lines are all connected under hood and at rear. At rear, follow them up to the electrical switch, it's on drivers side next to emergency brake cable (near transaxle). Also make sure the switch is still connected to the harness (one plug). Be sure to check the connections at the bypass valves themselves on the silencers.
Taz has posted in his Technical thread some diagrams/pics of the vacuum hoses routing and locations. All this is pretty basic but will require you dropping the rear plastic cover tray.
Pretty sure if they are not opening that's it's a simple fix.
Bill
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post #12 of 17 Old 04-22-2013, 08:50 AM
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The bypass valves are fail closed on the 575M , so no vacuum, no opening. Either a loose or mistakenly plugged vacuum line(s) or a faulty solenoid (rare). 360s and F430s and later V12s are fail open.
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Last edited by tazandjan; 04-22-2013 at 08:56 AM.
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post #13 of 17 Old 04-30-2013, 12:54 PM
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Hello at all,
Vafa, how go your by pass valves? Have you found the problem?
Today I have ordered the central x-pipes at supersprint in Mantova (Italy), next saturday I will put a button on the tunnel for the manual by pass valves opening ...
The modified that I will make will be completly reversible in order to restore the original equipment when I want.
The 007 operation sound Is started .....

Fabio

PRESENT: 575 F1 HGTC ROSSO CORSA 2004' - MB CLS 350 CGI 2007'
PAST: 550 ROSSO CORSA 1998' - MB CLK 240 2002'
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post #14 of 17 Old 04-30-2013, 02:14 PM
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Fabio- You will lose power with an X-pipe.

Taz
Terry Phillips

Present: 575M 135171
Past: Dino 246 GT 02984, 365 GTB/4 14009, 308 GTS 25125

Every day I look around, and if nobody is shooting at me, it is a pretty good day.
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post #15 of 17 Old 04-30-2013, 06:55 PM Thread Starter
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It turns out I did not have problem - I put styrofoam in the inner tale pipe and revved the car hard - when I got out, the foam pieces had been ejected 10 feet!

My car has X-pipes too. Some report better mid range torque and better exhaust note.

V.
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post #16 of 17 Old 04-30-2013, 08:30 PM
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Vafa- Some like the sound better, but back to back tests show the straight pipes produce more hp and torque. If you have a center muffler on a 2002 or 2003 575M (or any 550), then either a straight pipe or X-pipe swap is a good idea. If you already have straight pipes or X-pipes installed, though, swapping makes no sense and Fabio already has straight pipes.

Taz
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Present: 575M 135171
Past: Dino 246 GT 02984, 365 GTB/4 14009, 308 GTS 25125

Every day I look around, and if nobody is shooting at me, it is a pretty good day.
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post #17 of 17 Old 05-01-2013, 11:25 AM
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Vafa,
did you have installed x-pipes or the car had it when you buy?
Are you satisfac of the sound 575 with x-pipes?
Terry, yes probably with x-pipe will little lose of power, but I will also remove cats, then the budget probably will be positive ....
I try, if the results will be not good, I can back at the original.

Fabio

PRESENT: 575 F1 HGTC ROSSO CORSA 2004' - MB CLS 350 CGI 2007'
PAST: 550 ROSSO CORSA 1998' - MB CLK 240 2002'
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