Ferrari 328 electrical issue

I think we need a bit more information. When you say all electricals switch off, if the car is already turned off, what electricals are we talking about?

Does the car ever hesitate when you're driving it, as through you had a momentary electrical loss?
A mechanical connection issue might happen more when moving than when stationary.

How long after you switch off does this occur?
(Possible thermal expansion/contraction issue on a connection.)

From what you say, it sounds like you might be having a thermal issue somewhere.

When I bought my 328, I had an issue where the car wouldn't be able to turn over, about a half hour after shutting down.
It turned out to be the battery clamp binding.
After the battery and clamp had been heated by the radiator, after shut down, the battery post would contract faster than the battery connector, and the connection would get loose.

This didn't show as complete electrical failure, but it acted like a weak battery. (It would run lights, just not the starter.)

Filing down the battery connector clamp and adding some electrolyte gel solved it. 12 year later, it hasn't given me trouble since.

But there are other connections that might have cool-down differential contraction rates. Such as where the battery connects at the starter.

And I presume you checked the battery disconnect near the left front headlight?

 

I would check all battery connectors, including the battery cut-out.
Then check all connections at the fusebox and the fusebox itself. Problems in the fusebox with a 328/Mondial/Testarossa/F40 are a matter of when, not if .....

 

The diagnosis fits the symptoms exactly because if that connector contact became loose with the car running, it would continue to run, powered by the alternator. The problem would not surface until you stop the engine, which is exactly what you had.

 

It may be better to replace or remove the battery disconnect altogether. I can guarantee you it will fail sooner than later.

I cannot speak to your mechanics, but I've had my car in a very reputable shop for electrical issues and it took them quite some time to complete their work. Remember that there are several kilometers of wiring inside our cars and maybe a hundred connectors, and failures can occur anywhere. These can be the most difficult problems to diagnose.

 

Did your car ever have an alarm system installed? If there was an old alarm system and it was disconnected, but not entirely removed from the electrical system, it could be causing the problem.

Of course, you should also check the ground cable from the battery, make sure it's not corroded. Check the connection to the cut-off behind the left headlight, and check that quick-disconnect as well. Most often, electrical problems in old cars like this can be the result of a bad ground.

Just a couple of thoughts.

 

Duh, should have read the whole thread before posting a response. LOL Yup, those quick disconnects can be a major source of problems with the electrical system. Learned that from experience.

 

You're welcome!
That would be "Obrigado também". Portuguese, not Spanish, but close enough

 

What version 328 do you have "K-Jet without Lambda" (early euro) or "K-Jet with Lambda" (US) or "KE3-Jet with Lambda" (very late euro)?

K-Jet without Lambda looks like this:
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K-Jet with Lambda looks like this (note the extra gizmos between the fuel distributor and the intake pipe:
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KE3-Jet with Lambda has no warm-up regulator and has a small black box (the EHA) hanging off the side of the fuel distributor:
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Sounds like one of your coils is going bad, or a problem with a bad/faulty wire on one of the banks, or problem with one of the control boxes. It's easy enough to check whether one of the banks is not firing with an inductive timing light. If you start it up and it's running badly, just put the timing light on the hot lead from one coil, see if it's firing. If it is, then check the other. It could be something as simple as a bad ground on one of the control boxes, which was a notorious problem on the QV cars. Or one of the coils may be cutting out.

Just a thought.

 

The 328 uses a single ignition control box, but two coils. Each coil has an "amplifier module" that can fail, over time.
The ground doesn't tend to be an issue with the 328's Marelli, as it's mounted on a metal plate and has several ground pins.
(... three of which are "market selection" codes wired into the wiring harness, that set the ignition map for that market.)

The coils are also mounted HT lead down, so it could be as simple as a loose HT lead at the coil.
(DO NOT CHECK WITH IGNITION ON.)

This could also be the 10A fuse on the (O2 sensor) "protection" relay going bad, or the relay sticking.
(That relay is mounted on the under side of the panel on the right side of the trunk floor. The ignition controller is on the left side. (For an '88 US model.))

It may be easier to check for spark first.

 

Good info. I'm thinking 308QV setup, thought the 328s were similar.

 

Not really. The spare parts catalog (60M pdf) shows the parts on the plate, but only shows the two recesses in the trunk.

If you look under the carpet on the floor of the rear storage, on the right side, you'll see a plate bolted down. The protection relay, cat temp monitor, lambda computer, etc., are all fastened to the under side of that plate.

A similar plate on the left side has the Marelli ignition computer on its underside.

But as your issue is still intermittent, I don't know as there'd be anything to look for.

You might want to verify that both coils are firing, before digging into the bells and whistles bolted onto the CIS.

 

Here's a photo of the 328 protection relay (it's the thing with the red 10A fuse on the top) mounted to the underside of the RH trunk floor plate that DGS mentioned:
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The way it should be working is:

Terminal 30 should always be at +12V (even with key "off).

Terminal 87 should be +12V whenever the engine is running or the starter motor is cranking.

The latest manufacturer part number for this protection relay is 92861512402 (if you do a search on that PN you'll get some prior threads).

If your frequency valve buzzes/vibrates during the good-running period and does not buzz/vibrate during the poor-running period = most likely you have a problem with the protection relay or its wiring.

If your frequency valve buzzes/vibrates during both the good-running and poor-running periods = the protection relay is OK, and the problem must be elsewhere.

 

+1
I would also unplug the LT blade connectors on the bottom of each coil and check them for corrosion. Beacuse the coils are mounted upside-down, the rubber covers on these connectors funnel any moisture into the connector instead of keeping it out.