Mercruiser 350 Mag Alarm

[miller063]

Hi All, First time on this forum so appreciate any help i can get.
I have just installed a new merc. 350 mag engine in my 275 bayliner 07 model. All runs fine except i get the two beeps every minute alarm coming on every time i run it. When the merc mechanics scan it it shows a knock sensor code. I have replaced the knock sensor and it still does it.. I have removed the knock sensor from the engine and straped it to a rubber hose and it still goes off so there is no way that it is actually sensing a "knock". We are all convinced the engine is not actually knocking as we have fitted a manual knock box and can't hear anything unusual. The strange thing is that the alarm (2 beeps/min) goes off at exactly the same RPM. It is activated at exactly 3300 RPM every time i run the boat. If i push it out to 4200 RPM the continuous alarm will sound

Any thoughts on this would be most appreciated..

 

[alldodge]

Howdy

Could use a bit more info to be sure. Need to find out what ECM/PCM were working with

Is the motor a direct replacement for the 07 model, maybe a reman from Merc, and if so do you have your original serial number?
If it is a new 2016 model does it have a serial number?

The code your getting is this code 44 (knock test) or code 43 (actual knock)?

When the motor throttles up it checks to see if the knock sensor is working. This is only a split second thing and we would never notice. If the ECM cannot detect the sensor it will retard the timing, set a code and sound off. So if your "Merc Mechanic" does not understand this, you need to find another one

 

[miller063]

Thanks for your help.. I will check and confirm which knock code is coming up and confirm serial numbers

 

[thumpar]

You may also see if your "mechanic" can do a realtime scan on the water to see what the readings are.