After doing some searching on the Internet I came across the following site http://www.prosport-ferrari.co.uk/. It offers mainly spares for 360’s but in fact has new (and used) thermocouples for 355’s. Interestingly, I only came across this site when I was searching for a picture of the 360 thermocouple as I wanted to check that these were not installed in the 355 as was previously mentioned. Just goes to show you that it comes down to what terms you use in the search.

Given that I am not local to these people I asked about the total cost of shipping out to Australia. I received a reply that the total cost, including shipping, would be 85 UK Pounds. That turns out to be about AU$137! That was FAR cheaper than anything else I had found, so it was time to order. A few emails to Mike at ProSport- Ferrari and one very short phone call to provide credit card details and the part was ordered. Very simple and easy.

The expectation was that I would receive an email confirmation that the part had shipped but that hasn’t been forthcoming, which concerned me a little. The required amount has been deducted from the credit card so now it would seem that the only thing to do is wait. It has been almost 7 days since the order was placed so hopefully something should materialise after about 10 days. I have no reason to doubt these guys but it would certainly reduce my concerns if they at least sent an email letting me know that that the shipment was on the way. I also checked out their shop on E-Bay and there was plenty of good feedback and nothing negative, but guys if you ever read this, a simple email would go a long way! Aside from that these guys look like a good option for parts when further items are required.

The car got a short run again this weekend just to keep it ticking over. The ‘1-4 Slow Down’ light came on almost immediately after staring the car and did initially try and cut the cylinder bank. However, after a few minutes the light continued its random dance of going on and off while driving. After 15 minutes or so it was back again hopefully ready for a thermocouple replacement which will once and for all rid the car of the dreaded ‘1-4 Slow Down’ light. Please

The search for a thermocouple

Turns out that picking up a thermocouple for a 355 isn’t that straight forward. They aren’t as common as parts for other cars unsurprisingly. A contact referred me to Forza Automative who indicated they have a number of used thermocouples available. After checking a few other contacts this seemed to be the best option.
So early Saturday morning I dropped by Forza in hope that I could purchase a replacement and change it out this weekend. When we had a look at the thermocouples that were available the nut that locks one end into the catalytic converter was too small. It seems like these used thermocouples were from another model. Damm.
It was in fact lucky that I checked the size of this nut beforehand. It is about 14mm in size (or fits a 9/16 spanner), if you ever needed to know.
The only option now appears to be to purchase one from US. This one seems to fit the bill – 157501 Thermocouple.

Looking at this though, two things appear wrong. Firstly the bolt at the end that connects into the thermocouple to the catalytic converter seems small (like the parts at Forza) and secondly the length seems too short.

Looking at a thermcouple that is on Ebay (above) you at least see that the length of the thermocouple is much longer. Still also appears that the bolt on these appears smaller that what is on the car but that may be an optical illusion after staring at picture of them on the Internet for so long!
Looking at the connection to the car noticed a significant amount of thread still unused. Could it possibly be that the faulty thermocouple was from a 360 rather than a 355? That might explain why the nut was larger perhaps? However, after checking the thermocouple on the other side of the car it would appear that theory doesn’t hold any water as it is exactly the same as shown below.

So the only real option now is to order a new thermocouple from the US and see what arrives.
According to the parts diagram (above) item 35 is replacement part 157501 – Thermocouple, which is what is needed so…. Hi ho, Hi ho it’s off to the Internet with credit card in hand we go.
Here’s another example of a new thermocouple I found on the Internet

This seems to check all the boxes that it is the correct part given the bolt looks to be in the right proportion, the length is right and the part number (157501) is on the bag. Phew.
The car had a brief run to keep it active but continued to experience the “1-4 Slow Down” warning on the dash after about 10 minutes of driving. The light continued to flash intermittently but luckily the engine never went into limp mode. Hopefully, the replacement part can be ordered and delivered before the next potential run.
All this has taught another unseen lesson of owning a car like this. Parts for exotic cars are rare. Parts for old exotic cars are even rarer. You need to find a good source for obtaining replacement components and you will probably have to live with the fact that they will take a while to obtain as they aren’t exactly off the shelf items.
The other things that you learn is that the information you pick up from those who already have, work with, are involved with these sort of cars is invaluable. You have to of course sort the wheat from the chaff, even in this field, but those people are certainly out there and seeking them out is going to be the best investment you ever make when it comes to owning these sorts of cars.

Oh no! Not again!

Over the past few trips the “1-4 Slow Down” warning light has flashed occasionally on the dash. This is the same warning light for the cylinder bank that the ECU unit was changed a while back. About 20 minutes into the drive today the “1-4 Slow Down” warning light began to flash again. It kept doing so intermittently for the next few kilometres until the car went into “limp mode”. Oh great, not again.

Remembering that by turning the car off and on “limp mode” can be reset. Question is, will the car restart if it is turned off? It should, and at worst simply remain in “limp mode”, but you never know do you. After deciding to be brave and pull over, attempted to turn car off and on again. It started (phew) and “limp mode” was gone (hooray), however after a short distance again the “1-4 Slow Down” warning light had returned. Time to head back. On the return trip the “1-4 Slow Down” warning light continued to flash more than it had ever done in the past but luckily the car did not go into “limp mode” but you can certainly feel the electronic control unit attempting to shut down one of the cylinder banks. Luckily, it didn’t do that permanently, just had to put up with some stuttering.

The initial reaction to these sorts of problems (especially continued problems like this) is always emotional and extreme. The trick is simply to get over it (things could be FAR worse) and work out what needs to be done to get it fixed.

After a quick email to Sal DiMauro from Racing Red it would seem that the most likely culprit is the thermocouple that runs from the catalytic converter to the ECU unit (F highlighted in the image below. The problem one is the one on the right).


So the recommendation is that this will need to be changed. A check around the Internet seems to indicate that these thermocouples are around $200 so that shouldn’t be too bad.

A quick look under the car shows where the thermocouple connects to the catalytic converter, so it isn’t too hard to reach at all and all seems to be in order. All the connections are solid so it isn’t as though anything is loose. The connection at the other end of the thermocouple to the ECU is currently underneath a shield but undoing all that probably won’t make much difference as the connection to the ECU is solid. So, looks like it is time for a new thermocouple.

Interestingly, comparisons to the good thermocouple on the left hand side seems to indicate that the problem one, on the right, is more ‘worn’. It certainly doesn’t appear to be the of the same vintage. There is also a small clamp half way up the body that holds the thermocouple in place and prevent it flapping around. At least there is on the left but not on the right hand side. There is no clamp or nut holding preventing the problem right hand thermocouple from flapping around. These two fact seem to indicate that the problem thermocouple has been changed or ‘fiddled’ with at some stage. Interesting.

So now the hunt is on for a new thermocouple. Sigh.

The Capristo alternative

It turns out there is an alternative to replacing a faulty exhaust valve with one from Ferrari. Capristo make an alternative which is detailed here. It acts in the opposite way to the standard one that comes with the car. Instead of using the vacuum to open the bypass valve it uses the vacuum to open the valve. The kit apparently comes with all the parts and can be slotted into the existing connections without any problems. The other interesting feature is that if it fails, it fails in the open position, rather than the closed position as with the original valve.


An Australian supplier and price can be found here.

If you look at the Capristo vale you see that it has an improved heat sync around the diaphragm that controls the actuator arm. However, there is an interesting option that comes with the unit. You can actually get a remote that can be wired up that allows yo to manually open the valve on command. By pressing the remote, even at low revs, the bypass valve opens and you get an ‘enhanced’ sound from the exhaust.

The unit is not cheap (around A$1,000) and there is plenty of debate around the forums as to whether having the exhaust valve always open or close impacts the car in any way. There is plenty to digest on this matter and it will get posted up here once it is analysed in more depth. We are still not at the stage of replacement yet as it hasn’t been determined yet whether the existing exhaust valve on the car is damaged or whether it is the electrics. More on that research soon, however an interesting option to consider if the existing vale requires replacement.

The next project

The above shot shows the current state of the exhaust by-pass valve, which is located at the rear middle of the engine. At the bottom of the image you will notice a small metal pipe. That pipe should be connected to a rubber tube.
The exhaust by pass valve is highlighted in the above diagram (item N).
On closer inspection you can also see the tube that is suppose to run from the valve down to solenoid valve (S in the previous diagram) at the rear right of the car.
When the car was inspected the rubber pipe was reconnected but that still failed to make the exhaust by pass valve operate. The prognosis from the mechanic was:
“Replacing the missing pipe will not make the exhaust by pass valve work alone, I tried a pipe on there and it still did not operate.”
So what did that mean? Again, the response from the mechanic:
“With the exhaust by pass valve, it is currently closed at all times, whilst this will not damage the car it will limit the overall perform at high revs (albeit not to a noticeable degree) It also keeps the exhaust quiet all the time.Seeing as the valve still did not operate when I put a pipe on it, I can only assume it is the operating solenoid or wiring to the same, not a massive cost either way.”
So it would seem that the issue does not lie with the actual exhaust by pass valve, although there is no guarantee of that but that would be the most logical place to start fault finding.
Ok, so what does this exhaust by pass valve do anyway?

Here’s an image found on eBay of the complete unit.

Basically what happens is that a vacuum is created through the small metal pipe to at the top of the unit (on the left in the above image). That then causes the rod to retract (move to the left in the above image). That then opens the valve in the exhaust system. Ok, now what difference does having the valve open and closed make? Well from – http://www.the355.com/mambo/content/view/18/27/
“The bypass valve opens up at higher RPM, allowing the exhaust gases to take a more direct route to the tail pipes, thus increasing power and noise.This means your 355 is quiet around town but when you open it up it screams somewhat.”
Ah ha. So with it closed (as it always is if the valve fails to operate for any reason), then it doesn’t sound as good and doesn’t have quite as much power. That makes sense as the sound has always been ‘more subdued’ that expected. Now we know.
So how does the bypass valve actually operate? A vacuum is created at the inlet manifolds of the engine, this vacuum is used to feed a vacuum reservoir (item P in previous diagram) that stabilizes the pressure of the vacuum which then feeds a solenoid (item S in previous diagram) to control when a vacuum is present. The solenoid is opened and closed by the ECU and when closed there is no vacuum and when open there is vacuum to the valve. The solenoid has two pipes: one from the reservoir and the other goes to the diaphragm on the bypass valve – when the engine goes over 3500 RPM then the ECU supplies 12 volts to the solenoid which opens and that in-turn lets the vacuum get to the diaphragm moving the actuator and opening the butterfly valve in the exhaust.
Ok, so it seems there could one of three problems here:
1. The valve is physically jammed or mechanically broken and not able to open
2. The solenoid is not getting power from the ECU to open and close.
3. There is a leak in the vacuum feed.
Thus, the first most logical step to perform is to determine whether the exhaust by pass valve opens and closes. The actuator arm should therefore be able to move up and down freely. If that is good the would need to create a vacuum through the pipe to see if the valve will open. Now initially the mechanic said they connected the pipe and didn’t get the valve to open but that could still seem to be a problem with the valve or the vacuum. So the only way to know is create a separate vacuum and see whether the actuator rod on the exhaust by pass valve operates. If that is all good, then the problem is further back (as mechanic initially suggested) and more investigation would be required (and another posting!).
So we have a plan.