Shift interrupt switch for Holley HP EFI conversion

[miktwalker]

Hello All. New member to this forum and I need your help. Just converted my 1998 5.7 2 bbl carb mercruiser to closed loop EFI using the Holley HP system. The boat runs great with one exception boat will not come out of gear. Realized shift interrupt switch wiring is not utilized because not using factory distributor. Need to wire the switch into the system. Any thoughts? Thanks.

Mike

 

[Bt Doctur]

you can probably connect it to the neg side of the coil ,have any pics of the coil and dist wiring

 

[miktwalker]

I can get them but heading out of town for a couple days and need to catch a flight. Will post when I get back. Thanks for responding.

 

[Bondo]

you can probably connect it to the neg side of the coil

Ayuh,.... Welcome Aboard,..... That'll absolutely stutter the motor,....

Donno how the Holley ECM will like it,..??...

 

[Bt Doctur]

Thats why I asked for some type of diagram. Some systems will tolerate a ground and use a ground. others have 12volts applied to the ecm

 

[NHGuy]

If it's not in the Holley documentation I bet there is a help line you could call.. You can't be the first person to use that system in a boat.

 

[miktwalker]

Thanks guys for your help. Attached is the Holley pin map from the ecu. I'm sure there is a way for me to build a circuit to work with the shift interrupt switch. But in order to do that I need to understand how the switch works. For example I understand the concept of inhibiting ignition when the switch is activated by the shift assy. But how does the switch actually work? When I put the boat in gear the switch is depressed and ignition is not suppressed (naturally you want the boat to run in gear) but then how does it cutout ignition when in neutral when the switch plunger is in the extended position? Is it a momentary switch that only works when being extended from the depressed position? I don't understand how the boat can run in gear with the switch depressed and also run in neutral with the switch extended. Confusing to me.





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[Bondo]

Ayuh,.... The Only time the switch is activated is when comin' Outa gear, in the water, with a load on the prop,.....

 

[NHGuy]

And what happens is the v in the shift interrupt tilts which pushes in the momentary switch. That completes a ground to the ignition which ever so briefly cuts the ignition. When the ignition cuts the engine slows enough to allow the gears to disengage. When they disengage the load on the switch ends and the switch goes back to the center of the v which ungrounds the ignition. The ignition comes back on and the engine picks back up to idle. This whole thing happens in under a second.

 

[achris]

.... But how does the switch actually work? ..... Confusing to me.

Probably the best explanation of how the shift interrupt system works I've ever seen.

http://forums.iboats.com/forum/engi...3-how-to-how-the-shift-interrupt-system-works

Chris.........

 

[miktwalker]

Hey guys, and update. Holley EFI tech experts said wiring the switch to the negative side of the coil would have no ill effects on the ECU or EFI system. Wired it that way and tested most of the day yesterday to determine WOT for prop selection. Worked fine (for now) and now I understand how the switch system works. Thanks for all your help with this topic

 

[jimmbo]

You say it's a closed loop system. That means it has an O2 sensor. Where do you install the O2 sensor without it getting wet?

 

[miktwalker]

You say it's a closed loop system. That means it has an O2 sensor. Where do you install the O2 sensor without it getting wet?

Hey Jimbo,

Mine Came with an EFI kit I purchased from another company that I will not mention here because their system does not work. I purchased the MPFI kit from Holley and used the O2 sensor adapter plate from the first kit.

A lot of people make them now. Do a google search but here are a couple links.

http://www.mooreperformance.info/

http://wagsengineering.com/products/oxygen-sensor-spacer/