help with capristo bypass valve

I finally got to install my capristo bypass valve. For those that are familiar with this product, you will know that the valve requires vacuum to close the valve and springs back to open when vacuum is removed. Capristo supply a new solenoid valve to replace the stock one.

After driving around briefly, i have to say i can't really tell if the valve is opening or not. I think it is, because the car still revs to 8500 rpm. However, the car feels a bit less powerful compared with the original valve wired open.

My question is this - when the new capi solenoid valve gets a signal to shut the valve, doesn't this just hold the vacuum between the bypass valve and solenoid valve and thereby keep the bypass valve closed? I tried a simple experiment by inserting an inline tap in the vacuum line and when i close this tap off (effectively cutting vacuum to the capi bypass valve, the valve stays closed!

Anyone that has installed the capi valve, please provide me your opinions. I thinking that the OEM is better than the capi valve in this respect.

Thanks

 

If you put an inline tap and close it, you are not stopping the vaccum, since you have not relieved the pressure, you have basically sealed it at whatever the present vacuum is at. From that stand point, the oem valve would do the same thing, it would hold the exhaust valve open or closed at whatever setting it was at.

With the Capristo valve, you have to release all vacuum, for the valve to stay open. As an example, with my car running at idle, I can open the engine lid and see the valve position; that the valve is closed, and when I shut off the engine, the valve does not immediately open...it take several seconds for it to lose the vacuum, then it opens.

Try it and see.

 

Dave

I take your points, but how does the capi system work when driving the car? When you boot it, the solenoid valve will close and then the bypass valve slowly open? This surely can't be right.

 

It works similarly to the factory oem valve. It might be me, but it appears to open slightly sooner, by a couple hundred rpm, and seems to open a bit more willingly to throttle inputs. Meaning I don't have to press the throttle quite as agressively to get it to open...but it maybe that is just in my mind.

 

You know that the capi valve works opposite to the oe valve......no vacuum = open valve.

Put a 't' in the vacuum line and temporarily run a vacuum line (through the passenger window if you like) and a vacuum gauge into the passenger cabin. Watch the gauge as you accelerate and when vacuum drops the valve should open....and the power come on. You should be able to hear the difference when the vacuum flat lines. If you don't feel and hear the difference then something is wrong.

I played with my oe valve last summer (although I routed the vacuum line through the rear bulkhead to the cabin as my tests were more prolonged than a single run)

 

Did u not get the new solenoid from Capristo with the Bypassvalve? They should also have sent u the mounting instruction with the valve.

Kimmo /// Sweden.

 

The installation instructions are basically non-existant. If you ask the seller Nick at Nick's Forza Ferrari, he will provide you with a plumbing photo, but that is all he gets from Capristo. Capristo really should make a formal set of instructions with clearer diagrams/photos. If you search my thread, you can find it, and I posted the photo, along with my own, and some basic instructions.

BTW, Darren PM'd me, and said his Capristo valve was incorrectly plumbed by his mechanic and is now working correctly once the vacuum lines were correctly situated.

 

I think i have some answers to how the capi solenoid valve works. The mechanic who install the capi valve on my car had plumbed the solenoid valve in the opposite way shown on the photo from the capristo website. At first, i didn't think this would matter, as it is only a on/off valve. But, if the solenoid valve is plumb in this way, there's no pressure relief to the bypass valve when it gets a signal from the ECU (and therefore the valve does not open!). The 'free' tube on the bottom of the capi solenoid valve must be the relief path for the vacuum to escape. Hence, it is critical that the solenoid valve is plumbed correctly. Capristo don't give any instructions on this.

 

I also played around with the OEM solenoid valve. It works the same way but in reverse to the capi one. When it gets a signal from the ECU (12volts) the solenoid valve 'opens' and lets vaccum to the bypasss valve, thereby opening the valve. When the ECU 'removes' the signal, the solenoid valve closes and pressure in the bypass valve diaphram gets slowly released to the relief hole on top of the solenoid valve (hidden by the plastic cap). Not rocket science, but it shows that the solenoid valve must be plumbed correctly in order to operate the bypass valve correctly.

 

How much did you pay for the Capristo Bypass valve? Is it 63 mm inside the valve or bigger?

Kimmo / Sweden.

 

Be good if you can take some photos and post up the correct installation for future reference!

 

I paid $1450 Australian dollars. A dealer in sydney imported from Capristo, Germany. I didn't measure the inside diameter, but i think it is exactly the same as the OEM one which measures 60mm.

 

If you can find my thread, it is here on this site in the archives from my installation.

(edit) Here ya go: http://www.ferrarichat.com/forum/showthread.php?t=201300&highlight=capristo+valve

Also, the Capristo valve is sold by Nicks Forza Ferrari (site sponsor) for around $950 or so. Ping him for an exact price.

 

Can anyone suggest any suitable, non expensive vacuum gauges to the job? Links to websites would be helpful. Thanks.

 

Go down to repco and buy one of the cheap gauges, it will probably come with a peice of vacuum line in the box. This is all you will need for these tests

 

Actually, I don't think this is right. Both valves are vacuum OPERATED, but they are not controlled by the presence of vacuum in the manifold. They are controlled by the Motronic. There is a vacuum canister that maintains a vacuum, and this force is used to operate the valve, like a vacuum operated accessory (such as power brakes). The solenoid actually triggers the opening/closing of the valve, and this gets its signal from the ECU.

The difference between the OEM and the Cappy is that the default position (no action applied to it) of the OEM valve is closed, and the default Cappy position is open. This does not mean anything about when they open and close, only that if there is a failure, the Cappy fails open, the OEM fails closed.

You should be able to hear the difference on startup. The OEM valve is closed when you start the car. The Cappy valve is open, so when you crank it, the sound will be louder and then quickly quiet down as the vacuum comes up and provides power to close off the valve.

It also behaves differently. I agree that it seems to open faster. But more than that, it seems to stay open longer. Try this: blip the throttle sitting still, once. If I do this and watch the valve, it opens as the engine is settling back down - and the sound is no different. Now blip it three times. Here the valve opens as the engine is spooling down from the first blip, but it will stay open meaning the next two blips are noticably louder.

All of this is VERY apparent if you have a Cappy level 1, because the difference between closed and open is fairly significant.

I do like the idea of a valve in the vacuum line. This would be a very easy way to quickly switch between regular function of the valve and open all the time. I may have to try this

 

JS

How much revs do you have to give it before your valve opens? In your example of blipping the throttle three times, the valve would be staying open on the second and third blips of the throttle because it is getting a signal from the ECU. I don't think this because of the design of the capi valve. With the capi valve and new solenoid valve, if vacuum is applied, the valve quickly closes, likewise, if vacuum is removed, the valve should close almost instantaneously. I believe the reason why the OEM valve stays open after blipping the throttle is because the vaccum is slowly releasing through the breather vent on top of the solenoid valve after the ECU signal ceases.

 

I have the Cappy valve too, so what I am describing is what I have noticed with the new valve. I don't remember the OEM valve staying open like that, it shut almost instantly. It almost seems to me like there is some lag in both systems when applying the vacuum, like the vacuum action is lazy. For the OEM valve, the lag is in opening. The Cappy valve seems to be slower to close. I can't back that up with data, it's just my perception.

For the sake of argument, let's say the vacuum system takes a full second to do its thing, but the reverse action is almost instantaneous in either system...

OEM: You floor the gas at 2500 rpm. The engine starts to spool up. At 4500 rpm, the Motronic says "Open!" A full second later - now at near to 6000 rpm, the valve makes its way open. Then you let off the gas to shift, and the valve snaps shut. Back on the gas, the sequence repeats as the Motronic signals the valve to open but there is a lag before it responds.

Cappy: You floor the gas at 2500 rpm. The engine again spools up. At 4500 rpm, the Motronic says "Open!". Near to instantly, the valve snaps open, say by 4800 rpm. Then you let off the gas, but there is a full second lag, so the valve stays open. With a manual you can complete a shift in a second or so, and the F1 only takes 1/4 second. And then you are back on the gas with the Motronic saying "Open!" before the valve ever got closed.

The result is that you have the same signal timing, but the Cappy valve physically opens quicker/sooner and closes slower/later. I believe this is what is going on.

Right or wrong, you will not get my Cappy muffler - or Cappy valve - out of my car while I own it!

 

Are you certain you know what is happening? Solenoids are full-on, full-off valves where an electro-magnet opens (or closes) a valve, they are not proportional devices. On Ferraris they are full-off devices until current is applied by the Motronic ECU. Attached is how the 355 WSM describes operation for the OEM system. The bypass valve linkages have a spring pressure to close them. No vacuum, valves are closed. My personal opinion is the Capristo solenoid valve works like the OEM valves. Makes no sense otherwise. The OEM solenoid is designed to interrupt the vacuum, so should the Capristo's be. If you bypass the solenoid, the bypass valves are open whenever the engine is running and vacuum is present, and close when the engine is shut off. If you wanted to change how that worked, you would need a change to the Motronic engine ECU.

On the 550 and 575M the valves open above 2720 rpm and 64% engine loading. The 355 at 2760 rpm is similar, but no idea why it schedules at 4000 rpm in 3rd gear only. Note on the 355 parts catalog pages the vacuum accumulator 6 on the air injection device page, and the vacuum operated bypass valve 12 on the exhaust page. Vacuum opens the bypass valve as scheduled by the ECU/solenoid valve, and spring pressure closes it when the Motronic ECU/solenoid determines the rpm/load are below the mapped value.

If you can explain how it works differently, I would be very interested.

Taz
Terry Phillips
View attachment 355 Exhaust Bypass Solenoid Valve.doc
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I think we all understand how the 355 bypass valve works. JS, your example of the differences between the capi valve and oem valve sounds reasonable and plausable.

I would like to make the following points about the solenoid valve:

The Capi solenoid blocks off the vacuum supply when it recieves a constant 12 volts. The tube from the vacuum tank must go to the barbed tap at the top of the solenoid valve (same end where the electrical connector is). The tube from the bypass valve must go to the plastic tap jutting out at 90 degrees. The other tap point (which was brocken off by Capristo) must be free. This is the relief vent which allows the pressure in the bypass diaphram to escape (and therefore opening the bypass flap) when vacuum is blocked off at the other end.

The oem valve works exactly the same way, except that it needs 12 volts to open the 'gate'. Once the gate is closed, the pressure in the bypass diaphram escapes back through the solenoid valve via the vent at the top (covered by the plastic cap).

 

Here is a pic of how my capi solenoid valve has been installed. The OEM one was removed. The bottom tube goes to the top of the capi bypass valve. Notice the inline tap (just a $2, 4mm garden water inline tap). I installed this so could run with the valve open full time and then revert back to stock operation at the twist of the knob. Please note that my car is a UK spec. car, and doesn't have the third cat bypass ecu and thermocouple, therefore i do not get a CEL with the bypass valve open full time.
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Darren- I did some more thinking on the bypass valve and your explanation makes perfect sense. The stock bypass valve is spring loaded to close and the Capristo bypass valve is spring loaded to open. The stock solenoid valve is closed until it receives power from the ECU, the Capristo solenoid valve is open until it receives power. In the stock system, vacuum opens the bypass valve, in the Capristo system vacuum closes the bypass valve. There is only one ECU signal, and it can be used for either.

The 4000 rpm in 3rd gear had me puzzled, but one of our European readers explains there is a full throttle noise test from 50-60 kph the cars must pass in Europe. Extending the valve closed period to 4000 rpm in that gear most likely gets the car past that test.

Taz
Terry Phillips

 

The inline valve is great! I am going shopping this weekend

 

Be careful with running the valve open all the time. Brian Crall (Rifledriver) says it can cause engine damage on 355s. Hopefully he will explain why soon. About 2/3 down this thread.

http://www.ferrarichat.com/forum/showthread.php?t=236340

Taz
Terry Phillips

 

Here is Brian's answer. Running with those valves open all the time can cause some real problems on a 355.

http://www.ferrarichat.com/forum/showpost.php?p=138506346&postcount=18

Taz
Terry Phillips