Need help with sdl light please!!!

SDL means there's a cat temperature problem. Do you have an OBD2 reader. At least that way you could narrow the problem down to one side.

You say you changed the thermocouple/s? Do you know if your thermocouple ECUs are ok? If the OBD2 reader is telling you you have a problem on one side, at least you can swap over the thermocouple ECUs to see if the problem swaps sides.

Wrong air/fuel ratio can also cause overheating of the cats. Have you cleaned your MAF sensor, checked for air leaks, etc.

Cats are perfect? How did you establish that?

 

May be worth getting a laser thermometer to determine if cats are actually overheating vs a sensor issue- you can further diagnose from there. Getting a code reading from odb2 would help as well.

 

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Measure cat temperatures when the light comes on. If it's in the normal range, you have a cat ecu problem. Image Unavailable, Please Login
After 20 years, these things are a common problem.

Of course if you have an overheated cat, you have a real problem (misfire, bad injector, etc.) that needs to be fixed.

 

1. Read the OBD2 CEL code and see what that is.
2. Clear the code(s) after each time you try something new.
3. Let the engine relearn its parameters.
4. Check to see if you still have the black resin-coated Thermal Control Unit (if so, change them to green ones)
5. Clear the codes, drive the car until the SDL comes back, pull over and read the temperature of the Cat Converters and see if they are hot or not.
6. Remove the ECU connector, open its housing, plug it back in. Now you can probe the three temperature inputs to the ECU to see if they are 500mv to 1.5V (normal range) or not.

Armed with that data, we can go to the next step.

 

What fault codes are you getting?

Otherwise, the SDL is lit by the engine ECU based on the signals related to the exhaust gas temperatures it receives from the exhaust TCUs. The SDL will also light-up if the connectors of the Thermocouples to the TCUs have bad or intermittent contacts (they need to be very clean as they transmit very low voltage, some 10-30 millivolt. If the Thermocuples, the Thermocouple connectors and the TCUs are confirmed to be good, perhaps you can try with another engine ECU.

 

This could be an ignition problem resulting in raw fuel in the cats with resulting over heating.

 

See this 21-page message thread on how to diagnose ignition problems:

https://www.ferrarichat.com/forum/threads/cam-phase-sensor-malfunction.600131/

 

I qui

I quit paying attention to that thread because it is anything but a "how to". Feel bad for Grant, but it was time to sit down and outline a complete step by step plan of attack weeks ago. I posted a couple of times, time to start over.

As a totally irrelevant example, I have an EVAP problem on my Toyota truck. The service manual has a 7 page diagnostic procedure to follow and if that doesn't find the problem it referrers to 4 additional diagnostic procedures to be checked.

 

Ian, that is not going to help him.

Filippo, it seems to me that you want to try something easy. If so, buy a $500 Thermal Control Unit and start swapping out each of the three TCUs (left, right, center) one at a time to see if that goes away. Be sure to clear the CEL error code each time after the swap.

Good luck.

 

Sorry, Filippo, my tongue was firmly in cheek ...
I definitely wouldn't want you to read through 21 pages of confusion. However, I'm not saying there aren't things to be learnt in that thread. The traditional fixes didn't work and the problem was moving around. I think the steps that were taken would have worked for the average F355 ignition fault.

Filippo, could you clarify what you you have actually changed? Thermocouples or thermocouple ECUs? or all 5?

You must be the only person on the F355 forum who has actually seen an official diagram for the 5.2 car. Would you be willing to share it?

When you have an intermittent problem like this, it may be necessary to buy a data logging tool which records Motronic ECU data continuously and allows you to playback that data. By the way, we'd be interested to hear what codes you got before even though they don't seem relevant to you.

 

Is that a question or a statement?

What is what you started with? A data logger?

 

When you say, "idle control pump", do you mean the regulator? If the humming is coming from the idle control valve/regulator, that's normal.

See item 24:

https://www.ricambiamerica.com/car-diagrams/ferrari/v6-v8/355-group/f355-m5-2-1996/air-boxes.html

I'm guessing that your temperatures are in Centigrade/Celcius. 140C seems pretty warm, but I don't think anyone has taken the temperature of this before. There is no motor inside, just a solenoid-operated valve. The idle air regulator allows air to bypass the throttle butterflies when they are closed (at idle). It seems you don't have a problem with idle, so I wouldn't expect this to be faulty. I'm guessing that a stuck-open regulator wouldn't affect the engine too much above idle... The MAF is reading total air flow to the engine whichever direction it takes, so the fuel/air ratio should be normal.

I'll let the experts comment on cat temperatures. The WSM says the CEL flashes at 940C, so you're a long way from that.

 

You say cats are good. Stuck injector perhaps dumping fuel?


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you know, a few of us had asked what CEL codes you were getting and … mum.

 

Did you put in all new thermocouples along with new cat ecus? Double check the wiring that they are not swapped on the passenger side. Mine got swapped after the major and that kept throwing an SDL.

 

That is easy to do and it will cause both a SDL and CEL. The CEL code will be a good clue.

 

I thought I read he had no codes even after resetting which I found odd.