2003 5.0 MPI MercCruiser with 555 ECM resetting, engine stalls, single beep
06-05-2024, 07:15 AM
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2003 5.0 MPI MercCruiser with 555 ECM resetting, engine stalls, single beep
Hello,
I have a 2003 5.0 Mercruiser MPI with a 555 ECM. I bought the boat last year I had an intermittent problem with my port engine where at an idle or anytime below 2,000 rpm, the engine would cut out, solid beep from the alarm (same as when you first turn the key on), rpms will drop, and sometimes stall if it occurs at an idle. When the issue happens whether at idle or above idle (below 2000 rpm) it always single beeps as if you just turned the key on. If I was above 1,000 rpm say around 1,500 rpm, the rpms would drop and stay lower until I moved the throttle and then it would come right back to where it was in rpm (alarm would single beep as if you turned the key on). This year, the problem is happening more and it to the point now, that it happens every time we are out, sometimes over and over. I have a Rinda scan tool and there are not any active codes or any codes stored in the freeze frame data. Being that I have twin engines, I have had the scanner on both engines and compared values. One thing that stands out to me that isn't right is at an idle on the port engine, the timing advance stays negative and will drop as low as -14. On the starboard engine, the timing at idle stay positive and is somewhere between +1 to +10. The timing seems to advance fine on both engines as it revs up. It will advance on both engines to +2 at around 1,1100 rpms and continue going up to +25 ish around 2,500 rpm. Also, when the issue happens, single beep as if you just turned the key on, fuel pump primes, and the scanner looses connection to the ECM as if the ECM is resetting. Once it comes out of the issue, you can get the scanner to reconnect to the ECM. Things I have tried: I have swapped sensors from engine to engine including TPS, IAC, knock sensor 1, coil, MAPT sensor, CPS, and even swapped the ECM. I have unplugged the knock sensor on the port side of the block. It throws a code for the knock sensor, but the issue doesn't seem to happen while it is unplugged. The issue has consistently stayed with the port engine no matter what is changed. The only difference from last year to this year was I changed the cap, rotor, and plug wires all being Sierra parts on this engine and the starboard engine. The previous set of plus wires were Sierra as well and were only a few years old. Another thing to note is the engine runs great above 2,000 rpms without any issues. It comes on plane easily and cruises along fine. Any help would be greatly appreciated.
I have a 2003 5.0 Mercruiser MPI with a 555 ECM. I bought the boat last year I had an intermittent problem with my port engine where at an idle or anytime below 2,000 rpm, the engine would cut out, solid beep from the alarm (same as when you first turn the key on), rpms will drop, and sometimes stall if it occurs at an idle. When the issue happens whether at idle or above idle (below 2000 rpm) it always single beeps as if you just turned the key on. If I was above 1,000 rpm say around 1,500 rpm, the rpms would drop and stay lower until I moved the throttle and then it would come right back to where it was in rpm (alarm would single beep as if you turned the key on). This year, the problem is happening more and it to the point now, that it happens every time we are out, sometimes over and over. I have a Rinda scan tool and there are not any active codes or any codes stored in the freeze frame data. Being that I have twin engines, I have had the scanner on both engines and compared values. One thing that stands out to me that isn't right is at an idle on the port engine, the timing advance stays negative and will drop as low as -14. On the starboard engine, the timing at idle stay positive and is somewhere between +1 to +10. The timing seems to advance fine on both engines as it revs up. It will advance on both engines to +2 at around 1,1100 rpms and continue going up to +25 ish around 2,500 rpm. Also, when the issue happens, single beep as if you just turned the key on, fuel pump primes, and the scanner looses connection to the ECM as if the ECM is resetting. Once it comes out of the issue, you can get the scanner to reconnect to the ECM. Things I have tried: I have swapped sensors from engine to engine including TPS, IAC, knock sensor 1, coil, MAPT sensor, CPS, and even swapped the ECM. I have unplugged the knock sensor on the port side of the block. It throws a code for the knock sensor, but the issue doesn't seem to happen while it is unplugged. The issue has consistently stayed with the port engine no matter what is changed. The only difference from last year to this year was I changed the cap, rotor, and plug wires all being Sierra parts on this engine and the starboard engine. The previous set of plus wires were Sierra as well and were only a few years old. Another thing to note is the engine runs great above 2,000 rpms without any issues. It comes on plane easily and cruises along fine. Any help would be greatly appreciated.
