What plug wires are you running?

Mr Gadgets had all kinds of RF issues with his megasquirt too on his blower motor, chased it for a while, maybe he will chime in, Smitty

one major issue was when we tried non-resister plugs...was terrible, running MSD wires right now, but are going to try the factory ones with the shields on the plugs...they show a lot more resistance when you ohm them...also I have a 1 wire alt and the wire runs back thru the car(so master elec switch will work) and I feel it might be to close to computer and crank sensor(but crank & cam sensor wire are shielded) so going to change that as well...won't really know much till march or so now...thanks for all the idea's !!!

Are you running an MSD box? I've run into RF with Mefi's and an MSD box. That was one of the main reasons that I went to DIS. Make sure you ground the MSD and the ecm as far away from each other as you can. You can also wire in a capacitor where the box is wired. I've had good luck with that eliminating most, if not all, rf.
Eddie

No MSD box everything controlled by megasquirt..., thanks Eddie

Does Mark Boos have the ability to unlock and software to program the Merc PCM555?

What specific components would be required to convert a 2004 Mercruiser 469HO to the Holley EFI system and their component cost?

Thanks

Yes he does. So does Whipple obviously, and a few others as well. The most common way involves opening the ECU up physically but, I think Mark's hardware/software allows him to tune it more conventionally. Give them a call, www.pmefi.com.

For the Holley all you need is an ecm and a couple harnesses. Everything plugs right in to the factory sensors. The PWM style IAC may take a bit of tweaking but it is tune-able within the software. You can program in guardian functions, as well as warning lights, alarms, etc. I'll PM you some options and pricing if you're interested but it'll be less then $1500 including shipping.

Haxby.
What's a full holley hp efi kit worth? I know they don't come with injectors or pump but everything else in the kit?

A set up for what you want to do would be $3200 for everything including injectors. That's a 2000cfm billet throttle body with IAC, rectangle port intake, fuel rails, regulator, 48# injectors, intake gaskets, all sensors including O2 but no knock, HP ecm, wiring harness, ignition adapter harness, fuel pump block off plate, software and USB cable. It also includes a custom base Cal for your application and free tech support as well as remote tuning and datalogging if required. Holley makes an excellent billet fuel pump that flows about the same as an A1000 but uses less power and is much quieter. It can be remote mounted, or mounted right in the tank, - $250.

Is there any option to utilize the existing installed Merc harness via a converter harness to interface between the existing Merc engine harness PCM555 connectors and the Holley ECU connection?

Will the Holley ECU mount on the PCM555 engine mount?