I reallyneed some advice on my 550

Dave, on my 456, the Slow Down coming on already when cold, that just meant the Motronic computers had a fault stored. In my case P0102, MAF sensor, and as soon as that code was cleared, Slow Down disappeared.
My logic says it should have been the Check Engine light, but it wasn't

To make totally sure, measure temperature on cats, if low and even, it's probably like mine was...

 

If you can get the engine to run and the issue is present, can you compare the voltage drop across the L/R fuel pump fuses? i.e. put one probe on each side of the fuse (without removing the fuse)… assuming you have fuses with cutouts in the back. The values will be in millivolts. From these values and fuse amperage rating, you can use tables to determine actual current.

The only way a board is going to cause low pressure is if you’re not getting enough current to the pumps, but, it seems more likely he messed up the pump installation, there’s a restriction in the line or you have a fuel pressure regulator issue.

The Slow Down light could be a thermocouple or Thermocouple ECU issue. Technistrada have cheaper ECUs. Maybe you could also buy some of their “dummy ECUs” for faultfinding. The dummy ECUs replace the thermocouple and Thermocouple ECU (on a temporary basis), to prove it’s not those causing the issue.

Do you have a scanner? If so, that might tell you what’s going on.

 

dave are you near SoCal?

 

He's in Australia

 

First off you don't have to be sorry for a long post.
I can't see anything exotic with the issues you mention.
Replacing the fuseboard with an upgraded unit will always pay back over the long term, like the "cat ECUs".
The fuel pressure issue may be down to pieces of rubber from previous fuel pump supports that have crumbled apart and made their way through the fuel lines. I would replace fuel filters and have the injectors cleaned.
It is frustrating to not be able to enjoy a newly-acquired car, especialy a V12 Ferrari, but ALL of them suffer from OEM illnesses that need to be addressed in the hope to turn them into reliable cars. Hang in there and you wil be rewarded for your efforts.

 

You may be able to find an OBD2 adaptor ("Fiat 3 pin") and plug it directly into the plug on each ECU. I think it may be the plug shown in this photo (experts???)

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i.e. disconnect that 3 pin plug behind the kick panel and plug in your scanner to the 2 wire side.

I haven't personally done it on the 550, but I've done it on my F355. In my case, I had to supply power to the adaptor (from my cigarette lighter). It's a bit of a pain. I've been told that sometimes the Fiat 3 pin adaptor sold on Flea-Bay doesn't have the right size pins. I Googled it in Australia and it took me to an Australian site which had the right fit.

I think it was this one:

https://www.ebay.com.au/itm/135387138323?

The ad says Located in Australia, but you can never believe what they say. I think the one I bought came from Darwin, which I found odd.

 

Yes, that's the correct 3 pin adapter. I use an Autel AL519 OBD2 reader which has always worked well for me.

An easy way to tell if the system has stored a fault code is if, after turning the engine off, the amber "CHECK ENGINE" light at the top right of the gauge cluster turns on for a few seconds then turns off.

Note : From 2001 onwards the amber "CHECK ENGINE" light was replaced with the now current CEL symbol as found on all OBD2 cars :

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I've been told that on some Ferraris that that 2~3 pin OBD plug is used to transfer some data from the LH ECU to the RH ECU, but I haven't confirmed this. If it is the case, then you may not see all of the data on the scanner because you are breaking into the line to fit your scanner. Also, for all engine ECU scans, you will need to disable the immobiliser with the fob.

Actually, I'm wondering if disconnecting that plug will prevent the car from running? This might be an issue because some folks have said that the engine has to be running to get all data on the 550.

 

So, are you going to work on this car yourself? Or are you collecting information to relay to the specialist who got your car to this condition?

 

It's really valuable to do a nose to tail sorting. With a used car you have no idea what you have until you get in there. Records mean nothing. There is a great 550 sorting thread on this board. It gives you an idea of how to make a great running car. What it did was give that owner a new baseline going forward and complete understanding of how the 550 works making future diagnosis and repair easier and faster. You can have very flawless running if you do everything right the first time.

 

I’m sorry you are in the business and got taken. The number of used exotic cars sold in top condition are extremely small. Every one I have purchased over 40 years started with a nose to tail sorting before I enjoyed the first mile.

 

who was the dealer /repairer?

 

Well then Dave

1. The first thing you need to do is to make it possible to read the and clear any engine codes. Get that 3 pin dongle and an appropriate OBD2 scanner. Read the codes, write them down, and then clear them. The codes will tell you which bank is shut down, probably bank 2.
2. You have to figure out why one bank is shut off. I'll give some ideas below but the list is pretty big.

• Green thermal control unit is bad on one bank. This can be bench tested.
• Excessive fuel flow in one of the injectors. They are old enough to need cleaning now, especially if they don't get driven much.
• Bad injector wiring or engine harness. This happens all the time on Ferrari wiring harness of this era.
• Exhaust leak near the O2 sensor on bank 2. Read the live data or hook up an oscilloscope to the O2 sensors. There are real clues here.
• Bad wiring / bad relay controlling bank 2. At least you live on the same continent as Qavion, our local electronic guru.
• Also bad cam timing can do this. Did you check compression and leak down when you did your timing belt? Did you degree the cams? V12 is very susceptible to cam timing issues. Compression test can give a clue.

Good luck.

 

I thought all the 550's were obd2 capable but ferrari left out the connector on some cars to other countries. Aren't the wires in the approx driver's knee bolster area and wasn't there a TSB to show you how to connect the wires to have a functioning obd port? It would be useful to fix this 1st. Having access to the port is so much easier that going to the foot well all the time.