355 slow down 58 light HELP

My 355 is working just G-R-E-A-T. I took her for a short drive today and the following events happened:
Turned the engine on, let it warm for about 10 minutes.At idle engine speed the exhaust fumes smell like a very lean mixture (as if fuel is not burning well), no smoke.
The yellow "check engine 5-8" light comes on for about 3 seconds, followed by the red "slow engine 5-8" light for about half a second. They both turn off and I drive it out of my garage into the street. I drive normally(I swear), not exeding 4,000 RPM's between shifts (It still shifts like heaven). While driving (I insist, very gently) the lights go on intermitently in the same order (first the yellow one for about 3 seconds, then the red one for about half a second) The lights go on unrelated to engine speed, gear or car speed (never exceded the limit, I promise). Went back into my garage and left the engine idle for about 5 more minutes. The lights did not turned on again. Shut the car off and ran to my computer to write this!

Help! Is my baby sick?
JRV are you there?
Greetings
VS

Hi VS,
I had my "slow down" light come on and stay on the day before I left for a trip to Vegas in 2003. It was a simple fix...and might I add a part inwhich I had purchased a few of to have on hand, so I was thrilled that I was prepared. It only took a few minutes to fix - if indeed your issue is the same problem I had. I will email you a diagram. Hope it is as simple of a fix as mine was.

Doc,

sounds like the Regulator part of the Alternator may be acting up.

I say this because the Slow Down light has been rendered obsolete because you have test pipes.

Try the same exercise with the headlights and AC on Full and see if it happens more often.

VS,
Thanks for the nice thank you regarding the diagram, I sent over for you. I understand your special circumstances....nice!
My situation caused a noticeable decline in power. Due to the fact I was heading out the next morning for my Vegas event and leading twenty five Ferraris, I was so happy the fix was a quick one. Though I was prepared with parts I really hadn't scheduled in a car repair that day (haha).
Have a great day!

JRV:

You were right (again!). I drove the car with lights and A/C on, as well as the stereo (which I never use), and the lights would intermitently go on and off (like every 5 to 10 minutes of driving).
Then, I turned every thing off and the lights never turned on again.
Also, unlike Tambi's description of the same problem, I never experienced decrease in power.

I guess this confirms (again)that you know these machines like the palm of your hand!

Now what? Can I keep driving it like this or should I change that regulator?
Please advice.

Greetings

VS

Next thing to check, is that you have the ground strap from the alternator to the chassis, added. Ferrari did not put this into production until 1998 (I think), though many earlier cars have been updated, yours may not. If missing, you can buy the cable with the terminations for like $14 from the dealer, or just make your own.

If it is in place, then you should have your alternator tended to.

Doc,

you can keep driving until it gets worse, but at some point the battery WILL go dead when the Alternator actualy fails.

Dave's advice is spot on.

The Power Loss scenario occurs when the Thermal Probe (overheat detectors for the Cats ) Controllers fail. When a Controller fails it shuts the Injectors down on the corresponding bank. Usually when this happens the problem Controller can be unplugged restoring injector operation.

95-456gt started engine after winter rest. engine skipped!replaced plugs ran for warm up then roadtested' . started skipping again, dash lite came on 1-6 slo-down and loss of power!put innew gas and techtron ijector cleaner but condition continues on and off! whats the fix? thanks ferrarinut

Hi Tambi.
Noticed your article regarding the "slow down" light problem and hopefully the easy fix will cure my 96' 355 spyder. I've noticed this model doesn't have the added groudstrap for the alternator. Any info you could send would be truly appreciated.

Hi,
I own a Mondial t 3.4 cat with Motronic 2.7, which is the same as on the 348.
I had problems with the slow down light. First cause was a broken converter. Test tubes cured that.
Then I periodical lost 1 cylinder bank, but without warning light.
The temperature probe was not even in the exhaust!
The electrical diagram showed that the exhaust temperature ECU is connected to pin 52 of the Motronic 2.7 This is normally the input for the anti theft device.
The slow down ECU has three stages: 900°C flashing light, 940°C constant light and at 980°C it gives 12V on pin 52 which results in a cut out of the corresponding cylinder bank.

So it is worth a try to disconnect the exhaust temperature ECU. It is a connector with six contacts which easily can be unplugged.

Chris