164 fixed! (you may want to save thisone)

[VLADDS@domain.elided]

Remember my problem on the 164? Anything over 2700 RPM it would cut-off and 
show rpm counter at zero while flashing a check engine light, all during a 
fraction of a second? I fixed it! here's how:
if you check the wiring diagram, on the 164, the only way that the Motronic 
grounds itself is either through the fuel pump and then further to the rear 
grounding point in the trunk, passenger side, or to ground point 131, on the 
intake plenum. All the sensors are grounded there too. Problem is that from 
the plenum, to the engine, and further, to the chassis, electrical connection 
is not that straightforward. The only electrical connection to the head, 
(that has a strap to the block that has a strap to the chassis), is through 
the valve cover bolts.
What if those bolts are stained with silicone or threadlocker?
Well, the Bosch will seek another ground, and probably ground through one of 
the sensor, generating the known circus of randomly blinking lights in the 
dashboard. If partial ground (certain amperage probably) is available, the 
engine will run normally. If the ground becomes insufficient, it will cut off 
when the Motronic doesn't get enough juice. No code will show....
So, my fix was to run  a heavy copper gauge wire from the plenum to the 
ground point under the passenger headlight.
My suggestion is to do that anyway, just to avoid possible headache and to 
"miraculously" solve some of the blinking sensor lights, if you have them.
Thanks to all those that came up with suggestions, and Karl even pointed out 
the plenum, but I just could not put things together at that point. Also, the 
guys over here in Long Island, at Alfa Clinic helped me by lending me a used 
crank sensor, just so that I can eliminate that possibillity. Gota be 
carefull with that sensor, as, if you have a slack on the wire, the 
alternator's impeller will chew it.
Good luck everyone
Vlad
'91 164 L (fresh back from an Italian tune-up)
'85 Maserati Biturbo S (stopped leaking oil, although I use synthetic)

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