DIY replacement of Slow Down ECUs

Dear jznd, I delete mine fitting a simple plug with a 2,5v transistor between pin1 and pin 3, and sending pin 2 to earth, but I did that because my car is de-catted....
I don't understand if you want to replace your SDECUs with a your "functional" version, or instead just delete them.
Cheers!

 

The system throws a fault based one one or more of the following:

- The fault is real and the CAT is too hot
- The CAT temp ECU is bad
- The thermocoupler is bad
- The wiring is bad

All can be diagnosed and fixed. Removing the system is very dangerous as it can prevent an engine bay fire.

 

Yes.

 

Yes. It is plug and play. I put in the Gothspeed ones as they have a better reputation than the Ferrari ones. Solved all my light and driveability issues. I just sold 456 to the insurance company after it got damaged. I swapped old ecu’s back in before they took it. PM me if you want mine. Less than 200 miles on them. Comes with boxes and instructions. Takes about 15 minutes to change both using 7mm wrench.

 

HI everyone! I just found out that my car was decatted with tubi straight pipe ( I think) and it has always been a flashing SD. My mech had checked the thermocouples and they seemed new and good. Cat ECU looked Ok (green epoxy type, obviously it was replaced before)--no cracks. Do you think the removal of the Cat can cause the Slowdown warning? He also checked the wires with an Ohm meter and they seemed good. No misfiring, so faulty injectors can be ruled out. Do your guys think the ECU could be the culprit? I really want to solve this nagging issue on a otherwise a beautiful car with so much of comfort and torque.

 

The removal of the CATs won't cause this. It's in the other items I posted above.

 

Thank you Dave

 

Dave

Let say if all these items are replaced or swapped from another car to determine the real culprit, do I need to do the resetting procedure or just turn on the engine and see if the SD light still comes on?

 

I don't believe a reset is required. I know the system very well in a 355 and believe it's the same in other models. What car do you have?

 

A 550. Even at cold start now, the SD light is flashing. Before it was only at idling after a run or got stuck in a traffic jam when the car stopped and moved. Mine was an early 550 so the system is more or less like your 355.

Regards

 

I'll review the 550 WSM in the next couple days. If you are able to isolate the fault to one bank, you can swap components and see if the fault moves. That is the easiest low level diagnostics.

 

Yes, I have ordered a new ECU and will do the switch to see the SD goes away. Btw, is there an indication to tell which bank signals a slowdown issue?

Appreciate your kind assistance, Dave

 

You would need to scan the system with an OBDII or SD2 I believe unless 550's have a light for each bank which I don't believe they do. 95 355's did and 96-99 only have a single light.

See attached codes that relate


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OP go find my thread on this. Do what I did which is to apply 1.5V battery across some wires I specified in that thread. If the SD light is off with 1.5V applied then the problem is downstream to the applied short. If the light still illuminates then the problem is upstream of the applied short. That will help isolate your diagnostics. Then if you want better parts than ferrari contact drbob1 for his thermocouples which are more robust than ferrari. Once don't that leaves the SDECU as the issue downstream of the applied short. Then either get working Ferrari SDECU's or manually monitor with EGT gauges, or source aftermarket SDECU like the ones cribbj used or drbob1 used.

 

Nothing wrong with OEM thermocouples which are not made by Ferrari. The bigger problem is the temp ECU's. Not sure what happened to Goth's solution regarding those.

 

Dave, thanks for the info, very useful and I will pass it to my mech. Yes Fatbillybob, I remember reading your lengthy subject. I will report back once everything has been put back and tested.

Regards

 

When I bought my 456M, it did not have any catalyzers and had always the Slow Down on right from startup. When I put the catalyzers on, I never saw the light again.

 

F456M, thanks for sharing. Theoretically it shouldn't as suggested by Dave and others here but there are also owners who solved the SD problems after doing what you did. But mostly suspect the ECU being the problem. It's a mind blogging thing to solve.

 

has the 456M only got 1 warning light ?
on the 456GT you have 2, so its simply a case of swapping left and right exhaust temperature ECU units, and watching the lights switch over.

 

Chris, let me know if you still have the Gothspeed ones, and how much you want for them, and I presume you would ship to the UK please ?
PM me

 

I'm not familiar with the 456 but in most cases, the system does not work like that. I suspect when you had "no CATs" you also had not Thermocouples and when the CAT's were installed, so were the rest of the system parts. The SDL system measures CAT exhaust gas temp which will be a lot less with no CAT.

 

Hi ,
I have also removed the Cats on my car and am getting a CE light on. Can you please let me know if you would sell the transistors?
Please let me know.
Kind regards
Steve in NY

 

Steve - a CEL and SDL are two very different things. You are getting a CEL because the down stream O2 sensor is telling the ECU the CAT is not doing it's job (because it's not present).

To fake that out, take a look at http://www.bigdaddiesgarage.com/