Hi I am new to the F355 and trying to get to know the car a little. Anyone knows what these brass inlets as for? They look like vacuum connections..? I have capristo stage 2 and testpipes. Its sounds fabolous at full throttle but very very noisy also at cruising. I got a friend to push the bypass valve rod in and out without any whatsoever change in sound. Could the butterfly have gotten stuck in open position?? Mechanism moves on the outside, but perhaps not on the inside? Mats Image Unavailable, Please Login
If the valve is connected to the shaft and you can move it, I think the shaft must be rotating. Maybe the butterfly was removed from the shaft?
I digress, but is there a potential to damage the diaphragm in the actuator by physically moving it? There is a warning in some manuals about doing this with turbo wastegate actuators.
Capristo muffler and test pipes means y0u are always bypassing the cats already because they are not there. There is not going to be very much sound difference whether the bypass valve opens or closes.
There's a big difference in sound on my car with no cats and Capristo. Main cat flow path in the muffler is well, muffled. Secondary path is straight through and separate. (as far as I can tell) With bypass closed it's not loud at all in my opinion.
With my 95 and Tubi, when I had the test pipes on, the driver from 2 blocks back can hear my car. I took the test pipes off because it was causing running issues.
I agree. On my 98, I hear no difference with bypass open or closed as I have custom pipes and no muffler
Hi guys and thanks for your input. I took out the valve and the butterfly is gone as someone suggested. So thats that. I added some vacuum to the membrane and it works.. I hope there will be some difference in sound volume after fitting a new butterfly... cruising is unbearable for longer rides.. However it idles rough when cold, doesnt fire on all cylinders.. can test pipes have anything to do with it..? New temp sensors fitted on last service. When warm it purrs with that high nice note. Emissions when warm is good.
However there is another mystery for me that hopefully some of the more educated could cast light on. There is a tiny vacuum line in my car goes from the bypass valve membrane housing to the exhaust air injection plumbing right below... In my workshop manual however it appears to go further away and down to the solenoid valve located in the proximity to the airpump and vacum reservoir instead... How does this look on your 355 M5.2s?? Mats .
No, the vacuum line for the bypass valve runs along the secondary air supply tube. Have a closer look. Beautiful car BTW. See this photo. Image Unavailable, Please Login
In my experience, having straight pipes just buys you more trouble than it is worth. Put in some hi flow cats and you have some back pressure as well as some clean air. Your misfiring while idling might just go away. There is another thread on running issues somewhere on the 348 section. Same thing.
I've had stock cats, high flow cats and now test pipes. Runs perfectly with any of them. If others have had issues with test pipes maybe that's due to a different muffler, however no issues on mine.
The 95 I sold had test pipes. No issues .......well, besides making the people's eyes in the cars behind me water
Hi guys. of course, a closer look revealed the thin tubing that went along the bigger line. So no problem it makes sense now I put a new butterfly back in the bypass valve. I have not tried it yet on the road, but there is noticably difference on idle with valve open and close. Now it remains only to see if it opens like it should when driving fingers crossed. Ill see what happens with the test pipes Mats
Here is my 2 data points on my personal cars. 1995 Berlinetta 2.7 DME, test pipes fitted: it throws an engine light immediately after a hard throttle on the freeway where the bypass valve opens. After driving like that for a few weeks (200 miles), spark plug number 7 is fouled up and car runs terrible. Putting the high flow cats back, runs clean and never a problem again. 1996 Spider, 5.2 DME, test pipes fitted: the SDL light comes on because the exhaust temp at the thermal couple is too low. This happens 15 minutes idling in the driveway. Continued driving causes check engine light to come on because of SDL as well as low cat efficiency codes. Putting the cats back an ALL goes away. Your mileage will vary. But I no longer believes in test pipes on 355.
I had test pipes on my 95 F355B for 15 months without ever getting a CEL. I took them off because I want the car to be quieter.
The brass nipples you are referring too are for attaching a manometer to properly set the throttle plates. this is probably the most important adjustment to having the car run properly other then cam timing. On early pre OBD2 cars it is idle quality and emissions which can cause catalyst issues and warnings but on the 5.2 cars it is critical if you want the car to run right without check engine lamps and fuel trim errors. Very few technicians have the tools or understanding of these adjustments.
Hi there, yes testpipes will be history in my car very soon. Windsock, thanks for the info. As for the repaired exhaust bypassvalve - it is waaaay quieter now as it directs all flow through the full capristo muffler. Cruising is much more comfortable. Allthough it did not seem to open at any point... perhaps the reason why some previous owner took it off.. Solenoid problem? Any info on at what revs, gear and TPS it should see vacuum?? Cheers!
Which car do you have? 2.7? 5.2? US? European? I checked your profile, but couldn't find any details.
