355 Bypass Valve Removal Question

I haven't removed mine, but I did wire it open. Sounds soooo much better. The only problem is that it will trigger the check engine after 3 start-ups. No biggie... I can live with that. The removal looks like a simple removal of a few bolts.




Darrell.

 

Do yourself a favour and spend $150 for a challenge pipe or spacer some call it(part #170683) that will fit perfectly in place of the bypass valve. Later when the engine has been driven a bit and is good and warm....shut it down and turn the battery power off for 20 minutes or so ....then restart and let the computer take in all the readings..(at idle with all accessories off for 10 minutes)......This will stop the check engine light from coming on much. I suggest this procedure every couple of months to keep your 355 running the best it can. Also get rid of the cats and run test pipes...some like the hyperflow cats. Your car will love you for it and performance is improved along with sound. Specialized Itlatian recycling has one on ebay right now for $116
http://cgi.ebay.com/ebaymotors/New-Ferrari-355-CH-Exhst-Union-Ferrari-170683_W0QQcmdZViewItemQQcategoryZ42610QQihZ001QQitemZ8048311436QQrdZ1QQsspagenameZWDVW

 

http://cgi.ebay.com/ebaymotors/New-Ferrari-355-CH-Exhst-Union-Ferrari-170683_W0QQcmdZViewItemQQcategoryZ42610QQihZ001QQitemZ8048311436QQrdZ1QQsspagenameZWDVW

 

Remember guys, we are talking about two completely different cars here; 1995 2.7 motronic, and 1996-1999 5.2 motronic. You can wire the bypass valve open or replace it with the challenge piece on a 2.7 and the CE light should not trip or be illuminated. But it will set off the CE light after approximately two or more 30 minutes cycles on a 5.2 car. Turning off the battery and going through the 10 minute idle procedure ONLY effects the idle parameters. It does not "learn" the exhaust temperatures. My understanding (I do not claim to be a motronic expert) is that the exhaust temps (which is what trips the CE light when you wire open the bypass valve) are hard programed in the 5.2 motronic box.

Also it has been previously recommended by Rifledriver (Brian Crall) a master Ferrari tech, NOT to frequently reset your idle parameters. That it can actually create more problems that solve, if the car has to constantly relearn the idle parameters, rather than use the stored data.

 

Stick a golf tee in it. Then wire tie it to something so it isn't flopping around.

 

No long term ill effects from this mod?

 

I've gotten to the exhaust bypass valve on my 5.2 car. To gain access you need to remove the air boxes, then the heat shield. Not difficult, just a bit time consuming.

 

I believe that the long term effect of removing the bypass valve and the Cats is that your headers and valve guides will last longer but then thats just my opinion. Mine have been off for a decade and everything is honkydory. lol

 

I've wired my bypass valve open too because I hate the sound of that rattle or buzzing at idle. I've even replaced the bypass once but it wasn't too long before the rattle started again. I'm curious what you are going to have the machine shop do or if anyone has come up with a reasonably priced solution to this annoying problem? Given a choice, I'd prefer to have a functional bypass but haven't found a reasonably priced, long term solution.

If you have it machined in some way that stops the rattle, please share it and/or post pictures.

Thanks!

 

It has been explained to me that there are two things that cause the rattle. One is the bushings inside can wear. It is possible to open up and replace with new machined ss bushing. (that requires the assistance of a machine shop to cut the tack welds and open it up and to make a new bushing) Also, the spring appears to lose tension over time, and you can adjust the preload on it. Requires you to pop that rod off to adjust it, but you can add a few turns to it to preload the tension on it, to keep it shut tighter and prevent rattling.

 

I never hear mine rattle but then again its on the shelf.

 

I had an ex-wife that suggested the same thing for something else.....

We weren't married that long....


Mike in Kuwait

 

Where is this on the 355? I have a bad rattle, sounds like an exhaust leak but I have been told it is the bypass. Anyone have a pic?

What is the negative/positive of removing the bypass with a part like above?

 

On your car, you will get a "Check Engine" light if you remove it, or wire it open. Your first move is to try and adjust the preload tension. Second would be to find a machine shop to repair your valve. Last would be to replace it. Most seen to just replace them, but they are a pricey sucker.

I see an opportunity for a skilled machine shop to come up with an exchange program, much like others are doing with exhaust manifolds, water pumps and alternators. New ss bushing, and new spring inside the piece the vacuum line attaches to, and you would have an essentially new unit. With all the 355's reaching the mileage to require replacement/repair, the market is ready for this service.

 

Thanks for the reply. Where is the valve located?

 

The valve is located behind the motor, above the mufflers. The car sounds soooo much better driving with it open.


Darrell.

 

I had my local shop wire it open permanently by using metal wire strips. I have not had any check engine light whatsoever.. It sounds good.. Mine is a 95. Do It !!

 

Read the entire thread. There is no problem with 1995 2.7 motronic cars with wired open exhaust valve. The problem is with the 1996 to 1999 with 5.2 motronic.

 

I also have my exhaust valve permanentely wired opened, for more than one year, and had never any problem. As my 355 is a 97 model, what exactely could happen to the 5,2 motronic and not to the 2,7 version?

 

First of all are you sure your check-engine light works? Many people have been surprized to find out that it was taken out by the previous owner. I am not 100% certain of this but I think the reason the light comes on with the 5.2 version cars is because there are two versus one Oxygen sensors on the Cats. So the 5.2 cars are more sensitive to changes in the exhaust system. f355spider does this make sense?

 

Does anyone have an old bypass valve that they would be willing to donate or know where I can locate a used one? I'd like to experiment to see if I can come up with a permanent fix along the lines of what F355Spider recommended.