limp mode

[seaway]

Does my 1998 Mercruiser 7.4 mpi have limp mode or guardian mode? Thanks

[mmwjr]

Yes it does. Knocking or other faults will but it into this safe mode. An engine scan should provide the faults.

[seaway]

Thanks Mike. So, Mercruiser called it "safe mode" in 1998?
I think my engine is in safe mode because it will not go above 1500 rpm in gear, no sputtering or missing, just goes to 1500 and stops .

[mmwjr]

Originally Posted by seaway

Thanks Mike. So, Mercruiser called it "safe mode" in 1998?
I think my engine is in safe mode because it will not go above 1500 rpm in gear, no sputtering or missing, just goes to 1500 and stops .

Sure sounds like it. You need to scan the computer for fault codes. Did this just start and was anything done to the engine recently?

[seaway]

Yes, I did and engine swap from a 1998 7.4 carb to a 1999 7.4 mpi.
Mostly on my own since I can't get any Mercruiser trained techs. My local shops have long waiting lists. I'll be calling tomorrow about getting a computer scan. Thanks again.

[mmwjr]

Did you install all the sensors the computer communicates with? MAP, crank position, throttle position, O2, knock, .... a missing sensor will result in an unhappy computer.

Do you know if the donor engine is healthy and had no faults?

[seaway]

I'll call my local shop tomorrow for a computer scan.