85 QV stutters

It could be your digiplex box.

 

I just went through the wringer diagnosing an erratic misfire.

First off, confirm its spark, not fuel. My timing light on various ignition wires clearly identified mine as a spark problem.

If yours is spark too, determine if it is one bank or both. If it's one bank, you can swap coils and digiplexes to see if the problem moves.

 

I've got a newly rebuilt WUR if needed.


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Same situation here. Have ruled out everything at and after the coils. Will be testing Digiplex boxes and connections next.

 

Note that to "swap digiplexes" does not actually require moving them; you just unplug the connectors (clean them) and plug the connectors back into the other digiplex.

The hardest part of the procedure is moving the trunk carpet and undoing the cover plate at the bottom of the trunk (digiplexes are bolted to the cover plate).

 

If it's that fused relay down in there misbehaving, Buy the same relay for the Porsche 928. Cheaper and easier to find. There is one tiny mod you need to do to it but otherwise, it's a direct swap.

I think the Ferrari QV version is NLA

 

Don't forget to check those pesky vacuum lines while you're at it...

 

Of course this didn't happen to you but, for what it's worth, take a look at what is down in there and what I had to do:

http://www.ferrarichat.com/forum/308-328-sponsored-yellow-compass-group/461934-need-new-fuel-injection-relay-help-please.html