Mercruiser 6.2 diagnose mpi bravo

[etech2008]

Hello folks

first a little history. this boat came over from another shop the customer got it very hot hot enough that it is a maricle that it runs at all let alone good. The shop it came from replaced the waterpump as well as all the rubber. They shipped it back to the customer without river testing and of course as soon as they used it on the water buzzers galore!

I firsthooked up the computer and got a code for ect high so i deleted and as the buzzer went off it came back the engine thought it was still getting hot so I replced the sensor that problem was gone so I took her down to the water and it ran great we were cruising around 4300 rpms and as we were returning to the dock we got a beeb and lost power it was acting like a rev limiter was going off so I took it back to the shop and hooked it to the computer there were mabny faults for neutral over rev so I pulled swithch off it was partially melted to the bracket and replaced it problem gone so back to the water I went it ran very well at full rpms I did not run it much past 4300 rpms then a loan beep followed by another the engine never missed a beat.

So heres my questiobn I got a code several faults for overspeed well it was clear that it was not overspead so what controls the ovrspeed function is it soley the ecm also I was getting knock sensor 1 and 2 it isnt showing high or low that would indicate a defective sensor would the overspeed throw a knock fault? Also the computer was showing gardien howewver engine never missed a beat and it was showimg 100 % available power.

any experienced help would be very appreciated

thanks.

 

[Fun Times]

Re: Mercruiser 6.2 diagnose mpi bravo

Yes the ECM controls overspeed, But keep this in mind , Your overspeed counts will still count seconds while your in a guardian mode.

So for example say there is something wrong with the engine and the engine is in guardian mode at 3800 RPM's, If the ECM sees that your trying to go 3900+ RPM's then you are activating overspeed.

Check and ohm's check the wires to the knock sensors, They may be melted.

Clear the codes and see what comes back.

Do you hear the engine knocking?

Where you able to get to say 4800? Because if the engine can normally get to say 4800 RPM's, And you had say a 10% power drop, Then you would only top out around 4300 for example, Also that's when you would get the overspeed counts.

 

[etech2008]

Re: Mercruiser 6.2 diagnose mpi bravo

Yes it can get to full rpms Ill check those wires thanks