Technical details of 348 engine control electronics?

Hi All

My 348 (1992 European model) is a bit sick and I would love to know some details about why this is (without having to change all electronic parts one after the other to finally get it running well again...).

Here's the full story - it would be great to understand what is going on:

1) 1992 (possibly late 1991) manufacture date - owned since 1996 (originally 6'800miles , now 43'000 miles). Big service with timing belt and valve adjustments every 3 years or so.

2) The left slow down light has always lit up for very short times - usually when cold and usually goes out after one or two seconds - never had any noticeable problems due to this.

3) Recently (last couple of years) the engine would often stop when breaking at a junction so the idle motors [if that is what they are called...] were replaced. It was better but never really perfect.

4) More recently (on a long trip) the electronics would suddenly disable (what seems like) half of the cylinders and there would be no power to accelerate. This could last for a few seconds or even several minutes. Once it happens following the slow-down light blinking (a short time later) but usually with no connection between the two.

5) Usually it happened when accelerating - however when the clutch was pressed down the engine could be "blipped" to 7'000 with no problems, but as soon as the clutch was released it would seemingly restrict the revs to about 2'500 rpm - when 'slowly' accelerating through the gears to keep under this range so that it didn't cut off half the engine again it was consistently possible to get to a higher RPM (about 3'100) once in a higher gear (as if the limiting were also controlled by the engine load too).

6) Some times everything was fine - it was possible to drive normally for say 100 miles and then suddenly it would switch into this mode for a short (or longer period of) time and it was necessary to stay below 3'000 rpm to stop it happening - and avoid any acceleration where a sudden loss of power could be dangerous (eg. avoid overtaking anything but slow moving tractors....)

7) One I did a test on the motorway at normal cruising speed (about 3'200 rpm in 5th gear) - I simply took my foot off the accelerator and pressed the clutch - the engine slowed down and died, until the clutch was released and then it started again. This would however not always take place - sometimes it would drop to about 800 RPM and 'catch' itself before dying.

8) I also tried disconnecting the control units underneath the wings (behind the distributors) because someone said that these were probably playing up (I heard that some people change them often - also on 355s - since they go crazy with age (?)) but when disconnected there was no improvement and no real degradation either (?). With the motor running - actually connecting one of them (right) would cause the engine to stop, but disconnecting and connecting the other one (left) didn't do this.

Can anyone explain how these parts work - or should be working? What is their function exactly and why and how do they fail? What should be exchanged and how can a repeat be avoided?

Thanks!

Regards

Mark

 

Hi Guys

Many thanks for the answers - these are making me feel a lot better already; obviously I am not the only one suffering with these old-age problems and some clever and dedicated people have already help in hand.

I will need to do some checking into exactly which units I have (it is a shame that the Euro cars don't have the same support delivered as the US ones but this can obviously be solved).

One piece of info that I missed out giving was that the alternator was upgraded in 1997 to a Nippon-Denzo type since the original one was too weak. It blew the rectifiers twice (of course it always did things like that when a long way from home - to get back I had to buy three new batteries and change them on the road-side every 300 miles or so...). After the change the car also felt a lot better - I didn't realize how important having a good electric supply in the car was before!

In the mean time I have a picture of the car (from this summer) - it is in very good condition (including interior - apart from the fact that the plastic parts like the air vents are beginning to perish and have gotten soft - just don't touch them to avoid very dirty hands - but these will be sorted out; I understand that this is a weakness but someone told me of a technique of spraying then and then grinding the old surface off before respraying them...). The wheels are 355 ones with spaces, which makes for better handling and looks (in my opinion) - the original 348 wheels (a bit feminine) are on my Mondial 3.2 convertible - second picture.

I have also a collection of personal photos (with a fair number from Ferrari meetings in Switzerland and Italy, for example) on line here: http://www.mjbc.ch/homepage/index.html

I'll be back as soon as I have anything of relevance - looking forward to solving some problems and getting pleasure from driving the 348 again...

Regards

Mark
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Hi Guys

I have had two new exhaust ECOs on order - they are taking time to be delivered so I have tried to cancel these for the moment in preference to following the tips here to try to solve any basic contact problems.

First of all, yes it is a Motronic 2.7 and, since it is European model, there is no diagnostic button.

Someone told me that there is a simple device that one can also buy to read out the codes and display them - any one know about it?

I removed the covers behind the seats to see the connector cable and find that it has three pins on it - the kit than can be ordered is for an extension cable plus a push button switch; the switch seems to be connected to only two of the pins. Since the pins are easily accessible I was wondering whether I can't just connect two of the lines together to do the job?

Rather than damaging something by connecting the wrong pins together can anyone, who has one with their car, say which of the two need to be shorted together? Or is it more difficult than that? I will order the kit if necessary but I expect it will take some time to get over here...

Regards

Mark