Originally Posted by zz28zz (Post 4800101)

Was alternator used when running on dyno?
If not, maybe rectifier is going bad and causing elec noise??

Are batt switches set to "1 on 1" and "2 on 2" or are they both set to "both"?? Reason I ask is I recently lost a MSD box on my port eng (#2). Tach started jumping around, then a few stumbles, then dead. While idling back in on one eng, I switched both batt switches to "both". Tach on good eng started jumping around. Set both batt switches to "1" and tach behaved the remaining 2.5 hrs idling back in.

Originally Posted by cheech (Post 4800127)

Throttles at the helm opening up the throttle body butterflies all the way?
Do you have O2 sensors in the headers in the boat?

Originally Posted by sutphen 30 (Post 4800390)

you have knock sensors on these motors?

Originally Posted by SB (Post 4800560)

Disconnecting them doesn't always help. Typically When ECu notices knock sensor system not working correctly, it will go to preprogrammed 'safe' timing table. Read, less power. And you need power to get engine to enough rpm for the Prochargers to start doing their thing.

Originally Posted by zz28zz (Post 4801131)

Can you datalog the ign advance? If not, can you get a helper to check the ign timing on the fly to verify it's not retarding for some reason?