Slow Down

Pretty much the same symptoms on mine last year. The key for the dealer to diagnose was that the light came on when the car started. So there was no way it was cat overheating. My problem was the cat ECU's. Replaced them and no more slow down light.
Folks more knowledgeable can chime in.

 

I just had my cat ECU's replaced for the same reason too...

 

Does you bank shut down? Limp mode? Mine does and It's freaking annoying can't seem to resolve it. Let me know how you make out..

Thanks

 

There ECU's for the cats? Or are you referring to the two engine ECU's?

 

Vesicovini boxes.. Where the thermocouple from the cat plugs into under the engine cover panels

 

ah, right on. thx!

 

The purpose of the "slow down" is to keep engine damage from happening when the cats get too hot and start to plug up. Catalytic converters are not really much of an issue with todays engine management systems like it was on the earlier cars, Ferrari and everyone else really fought the problems with emission requirements post 1975 with the introduction of thermal reactors and then converters on the carbureted engines from that time, that is where this function originated. With the 360/430 having the slowdown fault, it is more than likely the control unit that is failing, not actually a problem with your converters.

 

if your cats have been removed the car will throw a slow down light randomly, nothing will work to eliminate it, unless you build the little devices that ferrari chat subscriber ( jevs) has on his ferrari 355 chat link. built two of them for my 360, yes they do work for the 360. no more sdl for over a year. they are simple to build. if your ferrari still has the cats then your problem is something else.

 

I'm getting that on mine too. Same exact situatuon except on startup. So enoying. It's in the shop now getting resolved. My guy thinks it may be a carbon buildup on a valve, not letting the valve fully close and then dropping unburned gas into the cat thus triggering the light. I think it's a sensor/ecu issue. Just had my 30k done too....However only 14 milage on it.

 

My slow down shut down issue has been resolved and passed emissions. Tested over 100 miles, so far it's running solid. It was loose connection on the drivers side cat ecu!

 

Thanks for the update Toolie. Just had my CS flatbedded to the dealer for the same issues. Intermittent "Slow Down" light, P0438/P1454, and shutting down of drivers side (bank 2). Will see what the dealer says next week. Seems like a lot of owners having this issue lately.

 

two cat ecu's replaced, all is well.

 

The ECUs are computers. They reside in a hot engine compartment. No reason to think a computer would fail by reason of heat, eh?

When I first got my 360, it already had around 15k miles. It ran fine and passed the PPI with flying colors. But run the car hard, and the Slow Down light would flash. No codes. Eventually figured out it was CAT ECUs. First one, then the other.

There was a design change, I think, so the replacements are the new models. But I'm not kidding myself into thinking they will last forever in that oven.

 

It was probably past exposure that did them in.

 

+1

 

The ECU's can get water into them with the heat causing the insulation to crack.

Did you replace one or both of them yet? It's going to be the ECU or the thermocouple that's gone bad. If you're getting a check engine light then its going to be P1445 or P1449..

 

Past exposure means just that. Unless you never run your car to operating temperatures or ever wash it, it will have been exposed to heat and wet cycles during prior driving, which could compromise one or both ECUs or thermocouples. The defects are then currently manifest in the behaviors you see.

 

He means that prior bake/cool cycles of the electronics have rendered them of questionable functionality. Could be something as simple as a PCB copper trace that cracked due to heat, then remains open until heated back up again. Or similar, inside a silicon device on the board...

 

Replace the cat ecus. Easy diy. They are like 370 each from ricambi. One on each h side under the big engine panels. Plug and play. I siliconed the tops with high temp silicone.

Did everything to fix the issue then finally broke down and replaced the ecus and seemed to fix the problem.