I have had my last go round with Holley. Be sides the long waits. Bad advice and overall bad experiences..........
My HP EFI would not recognize Bosch O2 sensors but it will the NTK (Yes i did the drop down change uploaded to ecu etc) Ntk is the only O2 sensor it will read otherwise is says unplugged. May I have two bad Bosch sensors. IDK but the NTK works.
After sending the ecu to Holly they inform me it works.
This system was installed by the EFI Store in Lake Havasu, very good install. harness etc done very well.
During this time the ecu would have interesting glitches, sometimes the usb would go online sometimes it wouldn't................Yes i have several cords including the holley type that screws in.
Fast forward to Friday I install ECU in boat again. clean all contacts with contact cleaner. Fire up land and all is well with world..............everything is working as it should be. We head to lake to tune idle, and run it through its learning...........(another issue it will sometimes learn sometimes not)
While tuning idle........................It dies. ECU is totally blank, wont fire. I attach computer to it and ecu will not sink, no ECU information is available. Nothing. We get towed to land pull out go home.......................try another computer another usb line and same thing. we try power disconnected for an hour and still nothing, delete and download software on both computers and nothing. I cannot get ecu to do a firmware update. it wont even sync or give me the time (RTC)
All fuses are good and power to unit tested and good, battery voltage perfect. ECU is basically not responding to anything.
Once again i am sending it fedex to Holley.
Thank go for good friends who towed us in,

Better call Haxby,

who is haxby?

He used to push the Holley EFI on OSO, not sure he's still around.

AH ok. It seems to work well with others, Mine doesnt. Im kinda pissed.

I never tried the Holley stuff,ran the old Cutler that Holley bought. It can be difficult, best of luck to you .

Alex.............About Haxby Speed & Marine | haxbyspeed.com

A friend of mines brother bought an older chevy street car a few months back. The previous owner didn't take many short cuts with the build. Car has a Holley efi system on it. My friend calls me to ask a few questions about the efi because both of them are carb guys. I took a ride over his house to give him a hand tuning it as he was saying it didn't idle well and it smelt of gas out the tailpipes. I'm not a professional tuner by any means but have had my hands on fast, big stuff and a few others and can hold my own. I was not impressed with the software all. Software program kept looking up (2 different laptops). Had to keep restarting the laptop. After changing a few settings I wasn't impressed with what I saw. I know people rave about the holleys. Maybe he had something else going on, but it turned me off on the holley system.

It sounds as the ECU might have a bad chip or at least a bad connection. It could also be the cable??

Hang in there, I know it can be very frustrating. Hopefully you will get the problem figured out and be able to start enjoying it.

Since your in LHC is Brian at the EFI store going to look at it with his experience ? He does a lot of holley installs but at times is hard to reach because Drag racing is still going on. You have a couple people over in the area that could help you out but I understand many are busy and you would have to hire them.

I have to agree that the support from Holley is less then Steller, but I hope you get it figured out and enjoy your boat.