Slow Down 5/8 Mondial T 1993

[348fred]

hi guys..
I got that red slow down 5/8 lights that appeared on a Mondial T 1993 that I recently bought. I noticed a lightly smoke coming out my exhaust.. not like the Cylinder head gasket one, but could be.. I suspected the catalyser to be down, but I took a look at it, they didn't seem to be out of order.. can anyone tell me how to test them? or what could it be? Thanks

[smg]

the slow down light is more of a 'STOP' engine light. the cats are fitted with probes that measure the heat from catylist and if they get too hot then it sets off the light any hotter and they will ignite, the smoke was a precursor to fire.

the engine is running rich most likely, check the plugs and wires. when was the last major done? the timing could also cause problems as well.

[348fred]

Now the car has 78100km.. last service was 71047km 19.07.2004. It's a lot.. I know. but do you think it would goes on fire? and after replacing the plugs and checked out the wires, what should I do? because if there's a precursor sign of possible fire, is there something else to do to prevent it? sorry for my bad English.. thanks

[ferrarilou]

A few questions if you don't mind:

How long does the car run before the slow down 5/8 light comes on?
Do you have to run the car hard to get it to happen?
When the light comes on, if you look under the car at the cat does it glow from the heat (happened to me once)?
Do both sides of the exhaust blow approximately the same amount of air?

I think there are a few things you can do:

1. If you get a temperature sensor, point it at both cats when the light is on and see if their temperatures are significantly different. This should tell you if the cat is really getting hot or if you just have a problem with the exhaust temperature probe circuit.
a. if it is really getting hot, then that side of the engine is probably either not
firing (so it is dumping fuel into the exhaust) or is running very rich. When this
happened to me it was because the electrical connection at the MAF was not on
tight. Ferrari's of that vintage (348 and Mondial T) did not do a good job of
supporting the wiring in my opinion and so the connections could work loose
over time. Clean the connection and reseat it. There is also a large screw-on
electrical connection at the top of the engine subframe at the left side
of the car that tends to lose contact over time due to the weight of the
cable dangling. Clean and reseat this. In short, would be best to clean
and reseat as many connections as you can easily reach if you have not
done this in a while. You can add contact enhancer as well, even the dealers
use it.
b. If it is not really getting hotter on that side, then I would suspect the
temp circuit. Check the cable at the temp probe first, but many owners
have had failures with the cat temp ECU over time. It is located in the
trunk behind the drop-down firewall panel. There is one for each side
and it just looks like a slightly narrow cigarette pack (black with resin
poured into one long face). It is important however to be sure that you don't
really have an overheating cat before you move to suspecting this circuit.

2. If you remove the cat on the 5/8 bank, try to look inside either end to see if it looks as though the catylizer material is broken. Does it rattle? A failed cat can still be a
symptom of the car running too rich (causing the cat to go bad as a result), so check that the engine is running right also.

3. You could send the catalytic converter to a refurbishment shop to have it tested. I recently contacted Random Technology in Atlanta GA (US) about one of my other cars and they can perform a flow test on the catalytic converter.

Hope this helps.



Lou

[348fred]

hi lou, thanks for your help..

to answer your questions, as you turn the key to position 1, the red light Slow Down 5/8 appears directly without starting the engine.. The engine seems to run ok.. I don't know when that red light started up to appear.. I bought it like that.. the car was almost 2 years abandonned in a parking lot.
about the glowing, I don't know, I'll check it next time when I'll go back to my box.. I had some smoke when I started up the car.. it was not a white smoke like the head gasket one, but it was some kind of grey and smell like burnt gasoline.. I suspected the spark plugs/wires to have defects, leading to an excess of gasoline in the cats.. which might have occured the grey smoke and the Slow Down 5/8 signal.. but I'll try to have a look at the different points you told me.. once again, thanks a lot buddy.

[ferrarilou]

Originally Posted by 348fred

hi lou, thanks for your help..

to answer your questions, as you turn the key to position 1, the red light Slow Down 5/8 appears directly without starting the engine.. The engine seems to run ok.. I don't know when that red light started up to appear.. I bought it like that.. the car was almost 2 years abandonned in a parking lot.
about the glowing, I don't know, I'll check it next time when I'll go back to my box.. I had some smoke when I started up the car.. it was not a white smoke like the head gasket one, but it was some kind of grey and smell like burnt gasoline.. I suspected the spark plugs/wires to have defects, leading to an excess of gasoline in the cats.. which might have occured the grey smoke and the Slow Down 5/8 signal.. but I'll try to have a look at the different points you told me.. once again, thanks a lot buddy.

If the slow down light is on all the time from when you start a cold engine, then I would very much believe it is a problem with the sensing circuit. The slow down light is only used to indicate that the catalytic converter is overheating, as far as I know. This can't be possible with a cold engine. So go ahead and swap the temp ECU from left to right and see if the problem moves as well. This is a very common failure. Also check the wire to the thermocouple and the connector near the cat ECU. More than likely you will find the problem by looking at these items. Swapping the thermocouples left to right as a separate step may be the next step if none of the other steps show an obvious problem.


Lou

[ManolinMondialt]

Originally Posted by 348fred

hi guys..
I got that red slow down 5/8 lights that appeared on a Mondial T 1993 that I recently bought. I noticed a lightly smoke coming out my exhaust.. not like the Cylinder head gasket one, but could be.. I suspected the catalyser to be down, but I took a look at it, they didn't seem to be out of order.. can anyone tell me how to test them? or what could it be? Thanks

I got the same thing when I first purchased my t. I took it in to the Ferrari Dealership and they said it was a bad thermocuple ECU or CPU chip. There are 2, one on the left and another on the right for each exaust I suppose. Anyhow, they changed it and reset the computer. Since then, Its come on only when I rev the engine too much through my gears. I've read up on it and asked a few techs. They all say to take it easy. I find that ironic since it is a ferrari after all. hope this helps. Anyone has corrections or additional statements to make i'm all ears.