348 Dreaded Hot Start Issue

The relay mod works great! My 348 cranks noticeably stronger.

sjd

 

My 348 cranks now as opposed to no cranking at all. Sure beats asking random stranger for a push. Although the bunch of middleschool kids I asked for help was excited to help. I bet the evening dinner conversation went like this:

kid: Dad, I helped push a Ferrari today.
Dad: why didn't you take any pictures?
kid: I would but it was so fast I did not have a chance, and you did not give me an iPhone.
Dad: sorry, next time.

 

What exactly causes the hot start issue. The relay does what? Impove the ground or bump power to the starter? seems fixing the underlying issue is preferred to improving resistance to symptoms of undwrlting problem?


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The long skinny wire from the key ignition eats up too much voltage and the starter solenoid does not engage. The relay fix uses the same signal to switch battery voltage directly to the starter solenoid.

 

what is it about time then? That is why does it not have this issue new? Also how does being hot affect it? One would think hot or cold that skinny wire takes same voltage.

Juat trying to understand it is all, not disputing any of this.

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As it ages or heats, the resistance goes up, the contact ring gets carboned up...click.

I'd be interested to take mine apart again in a few years to see if the relay mod helped the carboning by providing a good hard solenoid hit for every engine start.

sjd

 

A hot solenoid takes more voltage to energize.

 

I did the relay mod on my challenge cars also and added a remote start switch in the back. I added some diodes to keep from back feeding voltage to be on the safe side
Works great do the relay mod

 

I’m not familiar with the “relay mod.” Is this it https://www.ferrarichat.com/forum/threads/348-starter-relay-modification.202861/

or is there something more official?

No starting issues with my car but would like to keep aware.

 

Yes, that's what is done. One thing I noticed on the connections diagram (and mentioned in the first posts) is that Pin 86 of the relay connects to ground. The standard rule is that Pin 86 receives +12V and Pin 85 goes to ground. In the case of usual standard relays it does not matter which of 85 & 86 goes where but there are relays, same as the standard ones, but with an internal blocking diode between Pins 85 & 86 which requires that +12V goes to Pin 86. The blocking diode protects the contacts of whatever switch is activating and deactivating the relay and prevents the high voltage (~300 Volts) spikes at relay deactivation to enter the cars wiring. If such a relay is connected with +12V to Pin 85, it will blow the internal diode (the diode will cause a short circuit), probably blow a fuse from which the +12V comes and will damage whatever switch (if not robust enough) is activating that relay.

On the 348's relay panels, this rule is not followed (some relays have +12V on Pin 86 and some on Pin 85) and this is the first car where I have seen this deviation. Furthermore, the connections of "+"-s and grounds to the Pins 85 & 86 of the relays as shown in the wiring diagrams differ, in some cases, from how they are actually connected.

 

Another
https://www.ferrarichat.com/forum/threads/348-hot-start-problem-fixed.160866/page-2