Does anyone knows what "Slow Down 1/4" means?

The "slow down" light problem is quite possibly the #1 trouble area on the 348. It has been covered here many times.

In a nutshell, it is an indicator that the catalytic converter on that bank is overheating. But....there is a chronic problem with the electronic control units that send the overheating signal to the Motronic injection/ignition computers. Your car COULD have an actual problem with an overheating converter, in which case you need to diagnose and repair the cause of that problem. Or your car could (more likely) have a bad exhaust temperature ECU, and you need to take some simple tests to verify the problem.

In another nutshell, if the problem IS a bad exhaust temp ECU, you can simply swap the left ECU with the right ECU (they are located on the rear shock towers) and then drive the car. If the "slow down" light indicator is now reading a problem on the 5/8 bank, then you know that the problem is the exhaust ECU. If you still get a "slow down" on the 1/4 bank, then you have an actual problem with cat overheating. You would need to download the codes from the Motronic ECU's, check your exhaust readings, etc.

Tell us what you find.

Edit: I see now that this question is also posted in the technical section. I'm sure you will get good advice.

 

Jeff today was very hot and For the first time since I have this 348 the light CHECK ENGINE LIGHT 1/4 came up for a second and then went away.
What do you think about it?
Thank you

 

It was the "check engine" light that came on, NOT the "slow down" light?

If the "check engine" light comes on, you can usually download the stored codes in the Motronic ECU's to get an idea of what may be happening. After checking for stored codes, you can clear the memory and start over again. If there is a real problem, the code will come up again. If it was just a temporary "glitch", then it might be years before you see it again.

There are several threads here about pulling the codes and understanding them. It's not hard to do, and doesn't require any special tools or skills.

 

I will try what you said Jeff!!!!!!!!!! and I will post,thank you very much for your time

 

ops...........one little thing, how do you reset the ecu's? hot engine??? cold engine, ecc..............

 

There are two ways to do it.

The caveman way - disconnect the power from the battery

The proper way - pull any codes stored, then hold the button down for at least 10 seconds.

 

Ernie is right about the two ways to clear your codes, but his "caveman" way will perform the very, very, very useful additional step of clearing the "learned" air/fuel data from both A/F ECU's.

The 348's Motronic system actually learns as you drive, and it builds up electronic air/fuel "maps" that allow it to give you better performance for the condition of *your* individual 348 at the present point in its life. Kinda cool, really.

What Ernie calls the "proper way" above will nicely clear your trouble codes one at a time as you hold down the ECU button on each ECU, but that leaves the old Air/Fuel maps (sometimes you want this, sometimes you don't)....which is something that you do *not* want if you have made a change to your car such as swapped out a new O2 sensor, changed the resistance on a MAF, etc.

Here's the caveman way: http://webpages.charter.net/aircover/348/1994Ferrari348Spider.html#resetECU

 

Ernie e No Doubt, man, you are great!! I think that I will try to pull out the code first, and the...................Battery cave man style......later........what do you think??
I am changing the spark plugs with new iridium NGK and we will see if I will see again the CEL on!!
Oh............I am going to order something...........at Daniel..........I like his special offer on exaust and Hyperflow..............that will help!!!
regards