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How does Guardian Mode work?

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farmerbob

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I'm helping a friend with his 2014 Mercury 115hp EFI 4 stroke. We had a couple issues that we now have resolved, but engine acts like it's running at half power. When on the hose in the driveway, in fast idle the engine runs fine up to around 2000 rpm, then falls on it's face and won't go above 2500 rpm. When in gear, it will run much higher. Seems like computer is limiting it somehow.

We put it on the lake and can barely get on plane. After a while it will get on plane and get up to about 4000 RPM but no power.

We put a Mercury Smart Craft Connect module on it, and there is a Guardian Mode code in the history codes, but not active. Does the engine come out of Guardian mode by itself or does it have to be cleared with a computer? Or unhooking battery?

Thanks for any help you can provide!
 
There are two issues your discussing, In-gear and Guardian

When on the hose in the driveway, in fast idle the engine runs fine up to around 2000 rpm, then falls on it's face and won't go above 2500 rpm. When in gear, it will run much higher. Seems like computer is limiting it somehow.
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This is the in-gear switch. Your motor has a switch that tells it if the motor is in-gear or not. If it's not in gear the RPM's are limited, as you noticed it would not go above 2500

Guardian mode
This happens if parameters exceed safe limits for the motor.
Things like voltages are to low or to high, water pressures are to low, faulty sensor or 5v reference voltage is incorrect.

The short of it, the ECM things something is wrong and that needs to be fixed before it will allow full power. Smartcraft isn't bad but does not provide all the info that the ECM may be seeing. Why is that someone might ask, well Merc want's you to bring it in. You need a scanner like Rinda makes to see what is happening
 
Thanks for the reply AllDodge. I didn't realize these motors had an In-Gear switch that limited fast idle RPM, haven't had that on any of my boats, but my newest is a 2005.

I had an issue with low pressure lift fuel pump and have that fixed, as well as a bad temp sensor and that is fixed. After those issues are fixed is there anything that needs to be re-set to get out of guardian mode, or should the engine run fine on the next power cycle?

We might be at the point we need a dealer to do a diagnostic with better equipment. I'm disappointed in the Smartcraft module, and how limited the app actually is. Mercury has a couple other apps that use the module but are locked down for dealers only.
 
I won't swear in has an in-gear switch but Mercruisers have them, and with what your experiencing it would suggest such

Guardian should clear on it's own if it doesn't happen for a few cycles, how many I don't know but there is no performance issue unless it goes into it again.

RINDA
 
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