Hi Guys, I've had a very intermittent issue with my 85 US QV where, when shifting out of gear the RPMS drop like a rock as if all power is lost...or when coming to a stop, the idle drops down super low and then stalls. Sometimes I can drive 200 miles and not have it happen. Other times I can drive to the corner store and it happens 5 times. Up until recently, the car easily restarts right away. I've not been able to correlate anything specific with the behavior. As part of general maintenance, and with an eye towards eliminating the issue, we've replaced the WUR, crank position sensors, all fuel injectors, brake vacuum check valve, fuel accumulator, pump and filter. Also spark plugs, wires and extenders, distributor rotors and caps. Ferrari of Salt Lake has gone through the engine, replaced the 02 sensor, optimized the fuel injection and ensured the engine is 100% optimized to factory specs. It runs great, but still, the intermittent stalling happens. We replaced the ignition coils since they're some of the only "old" parts on the car and we're running out of possible issues. After about 20 minutes of great running and spirited driving, the car started bucking like a bronco, died and wouldn't restart until cold. We put the original coils back in, and the same bucking / dying thing happepned. Any ideas?
I thought this was pretty ingenious way to determine if it was the ignition system. I think you mentioned you replaced the failing coils, but check this out. Monitoring the spark plugs and their firing is brilliant. At least you can isolate the problem. Spark or fuel. hope this helps. -R
Reviving an old thread because the problem is solved! And the answer was so simple. I finally found a great independent ferrari mechanic who took a fresh look at the car. He determined that the battery had one or more bad cells and theorized that it might be causing some gremlins. He replaced the battery and the car is now rock solid. SLC Ferrari had my car for the better part of a year and couldn't solve the issue (despite thousands spent on dead-end diagnostics). Kudos and thanks to Paul at Euro Planet!
If they go wrong you get bad misfiring and/ or fuel dilution of the sump oil. It overfuels on a cylinder and it runs past the piston into the sump. The one i saw put near a ltr of fuel in the sump
