496 MAG intermittent shut offs problem
 

Hello everyone. I'm new. Been reading this forum for quite some time and the information available is excellent. I've developed an issue with my engine. Hopefully some of you could lend a hand. Every now and then it seems to shut down for a fraction of a second. Almost as if someone turned the key on and off very quickly. It's not a stall per say, it literally feels as though the engine was turned off. There are no alarms when this happens. It did it again this past Monday, only it lasted for about 1/2 second. When it came back on it wiped out the upper gear set of my Bravo 3. The clutch friction welded to the forward gear. Now I'm worried this will happen again unless I figure out what's going on. I bought the Techmate Pro scanner. There was nothing unusual in the fault history but there were CAM and CRANK sensor faults in the Freeze frame from about 50 hours ago. If there were recent CAM or CRANK SENSOR events would they replace the ones from 50 hours ago? I'm not sure what else would cause the engine to do that.

Hard to believe it took out the drive and Im not a 496 fan.... but id think any alarms would supersede and show current faults if there were any, was there work done to the engine 50 hrs a go ?

Nope, no work done to it. It took out the drive because it acted like a neutral drop. There's no alarms. It starts a runs like a gem. It just does this momentary shutdown now and then. Usually it's just a blip. A hesitation. This last one was a little longer and thus wiped out the drive. Are IAC's still in the equation when off idle? I've noticed a few starts in the past where there's a bit of a struggle on startup. Sometimes it will stall out and starts right back up again.

I wouldn't think so on the IAC, is this a cruiser with the B-3 , what rpm were you turning when it happened

The drive destroyer happened at 3200. The last two times this happened that were just blips so to speak were around 2800. Boats a Chaparral 270 Express cruiser

Loose connection somewhere
Kill switch, key switch, battery power connection

Start removing and cleaning connections, engine connector, harness connectors, ECM
Place a meter on key and kill switch and see if you can make it loose connection

I've never been into the throttle quadrant before. Can that little toggle switch wiring ever interfere with the throttle arm itself? Because every time this happens the throttle is physically in the same spot

Dont fully understand the Throttle quadrant but if your talking about the kill switch. And if it can get tangled with the wires, then sure. Wojld not think it would happen very easy because of how the wire and cables are layer out

This is a tough one because of the intermittent nature of it. Scanner shows nothing. Just the two old cam and crank codes from 50 hours ago. The fear is after a $5000 drive repair it could happen again on the first day out. Usually on initial turn of the key you get a normal single tone alarm briefly. This cutout that occurs does not do that so I don't think I'm losing actual power or I'd assume I'd get the alarm. Like I said, the cutout is usually very brief. Like a hiccup. But this last one went out for about a second, and when it came back on it did so with a slam. I started the engine without the outdrive today and shook the ignition cylinder, pounded on the throttle quadrant and cutout switch and nothing. It ran fine. And the scanner reports all is well.

Normal is 2 beeps, right?
Don't think that is the thing, but wonder if if were over looking something. Right now like you, I have no idea what's going on