[Guest]

Ok, here's a somewhat theo

Ok, here's a somewhat theoretical issue about the Marelli boxes on my 2v Mondial 8. I've been examining workshop manuals, wiring diagams, and any postings I can find about the tdc sensors with no luck. Each of the sensors go to only one box input, not shared as the tach sensor is. Since the box times the spark to its bank based on the Hall sensor output, and the flywheel tdc sensors (but not the tach)are in the same plane, and would trigger both tdc sensors as it turns, how does each box distinguish between bank 1 and bank 2 triggers? Since Hall sensors are dependent on magnet polarity, could the two flywheel sensors be polarized differently?

The alternative is that the boxes fire on both signals, but that means that both banks are getting spark and the K Jetronic CIS is spraying fuel into all cylinder runners, despite the valve positions. That hurts my head. Help! What (possibly obvious) factor am I missing?

 

[Guest]

The spark is fired based on a

The spark is fired based on a predetermined map in the Digiplexs, based on rpms the engine is turning with the addition of a vacum input.

HTH's

Regards, JRV

 

[Guest]

"but that means that both

"but that means that both banks are getting spark and the K Jetronic CIS is spraying fuel into all cylinder runners, despite the valve positions."

Yes - that is true - that is why it is refered to as a Constant Injection System (CIS). The injectors are always spraying while the engine is turning ( or more correctly, generating a vaccum induced airflow across the airmass sensor plate)In the Kjet cars, the ignition and fi are separate systems. The ignition is mostly two systems with two separate coils.
This is why you can have single bank failure and the engine will still run, pumping unburnt fuel into the exhaust.
best
rt

 

[Guest]

[IMG]http://www.ferrari-talk.c

Yes, thanks jrv! Understanding, then, that the vacuum and rpm/tach inputs are for calculating advance at speed, is the tdc signal a starting point reference to the Marelli so it can compute subsequent advance?
I'm trying to understand this because I'm looking into aftermarket systems. I've seen a lot of posts here and elsewhere, but not much on how they technically handle the F-car (2, 4 cylinder V-8) concept, but possibly using the stock timing inputs instead of an add-on trigger wheel. The old brain cells aren't firing on this the way they should. Thanks again,

Tom

 

[Guest]

Hi rt, what's new with the

Hi rt, what's new with the Mondial? With a lot of luck (and the creek don't rise, etc) someday mine will look/run like yours.
I posted my last comment before rechecking the thread and seeing your post. I know that the aftermarket ignitions have different amounts of flexibility as to the timing input, I understand that systems like your electromotive use a new crank trigger wheel. Does it only have one magnet or two?
Tom

 

[Guest]

>>is the tdc signal a

>>is the tdc signal a starting point reference to the Marelli so it can compute subsequent advance? <<

that's correct....