Slow down light - Ferrari Life
 
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post #1 of 11 Old 03-26-2018, 05:28 PM Thread Starter
 
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Slow down light

Both catalytic converters have been removed (and not replaced) on my 99 456M GTA. The amber Slow Down light is flashing. My research tells me that the current cat 02 sensors are causing the ECU to throw the SDL warning. Will the light go out if I place 02 sensor spacers (Spark Plug Non-Foulers) along with the rear 02 sensors? Do Bosch or TDK 02 sensors fit with the standard spacers available at AutoZone or are special spacers needed? Also, how difficult is it to fit a spacer and rear 02 sensor in the small space available? Do the front cat 02 sensors need to be likewise treated? Thanks for the help.
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post #2 of 11 Old 03-28-2018, 06:16 AM
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Traditionally, the SDL is triggered by too hot exhaust temperatures in the catalytic converters, measured by thermocouples at the exit of the cats. I've always believed O2 sensors had nothing to do with SDL's.

Recently however, some owners have reported that they've experienced SDL's and they've replaced things like their main batteries, the O2 sensors, RPM sensors, TDC sensors, etc. and the SDL's have disappeared afterward. Personally I don't buy it, but.......

I've done a fair amount of R&D work on these SDL systems as I had developed an in-cabin instrument to show actual temps AND trigger the SDL's when appropriate, so I'd like to know more about your current issues.

Is your 456 an early model or an M car? Reason I ask is to know which version of the Motronic ECU's you have. I'd also like to know if you still have the cat thermocouples and their ECU's in the system or not?

'99 550, Rosso Corsa / Nero, S/N:114654, Assy: 31836, Engine: 52084

High mileage, low compression, and missing on a few cylinders.....just like my cars.

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post #3 of 11 Old 03-29-2018, 07:28 PM Thread Starter
 
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1999 456M GTA. Bosch Motronic M5.2. Original cat thermocouples and ECUs remain in system.
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post #4 of 11 Old 03-30-2018, 01:42 PM
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There's a problem with the slow down circuit, inputs, etc. As John said, this has nothing to do with the oxygen sensors. The car has two slow-down lights, one for each bank. Are they both blinking? What did you do with your thermocouples? Was the slow down light flashing before the cats were removed?

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post #5 of 11 Old 03-31-2018, 02:00 PM Thread Starter
 
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My 456M GTA only has one SDL warning on the dash. It alternates amber with the red Check Engine Light (CEL). After the burnt cats' internals were removed from both sides, the cat casings were welded back together and reinstalled in their proper positions behind the manifolds and connecting to the exhausts. The thermocouples were reinstalled in their original proper positions. No, the SDL was NOT flashing before the cats were removed.
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post #6 of 11 Old 03-31-2018, 03:15 PM
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Well...
If the cat internals were hot enough to be "burnt", there's a possibility that a code (overheat/out of range) was set in one of the ECUs. You could guess and throw money at parts, or simply find a shop that has a factory SD tool to see what's stored and what temperatures are currently being "returned" by the thermocouples. The only meaningful research that could be done would be with some diagnostic gear.

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post #7 of 11 Old 03-31-2018, 03:33 PM
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Another thought...
If the engine issue(s) has/have been corrected (the one that "burnt" up the cats), why not replace the cats. They do not hurt performance. You won't be needlessly polluting the air.

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post #8 of 11 Old 04-01-2018, 05:43 AM Thread Starter
 
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Ricambi parts to replace the cats total >$9K;then there is labor costs. Cats are not needed for emission tests in my state. Don't shame me about polluting the planet.
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post #9 of 11 Old 04-01-2018, 06:43 AM
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If your cats are gone and that's the way you're going to keep the car setup, there's no reason to keep the Cat Overtemp safety system. PM me and I'll give you some more info.

RE: replacing the cats - not trying to "shame" you, but you might want to think about the resale value of a car that is modified and has no cats, and won't pass most state emissions inspections. There are places that will take your old cat housings and will "recat" them with newer, higher efficiency cats. Might be worth investigating......

'99 550, Rosso Corsa / Nero, S/N:114654, Assy: 31836, Engine: 52084

High mileage, low compression, and missing on a few cylinders.....just like my cars.

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post #10 of 11 Old 04-02-2018, 03:55 AM Thread Starter
 
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Slow down light

Thanks for the PM John!
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post #11 of 11 Old 04-02-2018, 05:24 AM
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You're welcome; The way I proceed with any mod is to do it in a way that I can always undo it and restore the car to stock.

A stock, unmolested car will always fetch a better price at resale than one which has been modified, no matter how well the mods were done.

'99 550, Rosso Corsa / Nero, S/N:114654, Assy: 31836, Engine: 52084

High mileage, low compression, and missing on a few cylinders.....just like my cars.

Maranello Skunkworks Team Member
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