454 MPI advance timing issue
08-26-2020, 03:37 PM
#31
No you do not have that problem. The specific issue you are referring to was for a small batch of 454/502 Mag EFI/MP motors around 1994-1995. There was a Merc service bulletin put out at the time addressing the issue. Basically during engine start the ECM would advance timing until knock was detected which verified the knock sensor was working. If it didn't detect knock it would trigger a code and retard timing. This does not apply to your engine.
ok thanks!!! Any ideas what would cause what I’m experiencing?
08-26-2020, 04:01 PM
#32
Registered
Since your getting the code the ECM is retarding timing, if the code was not ON the code would not show. It can be fixed easy if your ECM is no locked, most are not. Need MEFI Burn or other, down load the BIN file, turn the flag OFF, and reload it. I bought MEFI Burn to get rid of the same issue.
Running 93 is what causes the issue. Your motor is designed for 87, and running 93 means the ECM cannot advance the timing far enough to make it knock, so the code is thrown. My repower requires me to run high octane (89 or 90) so it would throw the code every now and then, and would really do it when running 93
08-26-2020, 04:42 PM
#33
I'm disagreeing
Since your getting the code the ECM is retarding timing, if the code was not ON the code would not show. It can be fixed easy if your ECM is no locked, most are not. Need MEFI Burn or other, down load the BIN file, turn the flag OFF, and reload it. I bought MEFI Burn to get rid of the same issue.
Running 93 is what causes the issue. Your motor is designed for 87, and running 93 means the ECM cannot advance the timing far enough to make it knock, so the code is thrown. My repower requires me to run high octane (89 or 90) so it would throw the code every now and then, and would really do it when running 93
Since your getting the code the ECM is retarding timing, if the code was not ON the code would not show. It can be fixed easy if your ECM is no locked, most are not. Need MEFI Burn or other, down load the BIN file, turn the flag OFF, and reload it. I bought MEFI Burn to get rid of the same issue.
Running 93 is what causes the issue. Your motor is designed for 87, and running 93 means the ECM cannot advance the timing far enough to make it knock, so the code is thrown. My repower requires me to run high octane (89 or 90) so it would throw the code every now and then, and would really do it when running 93
08-26-2020, 07:26 PM
#35
will try 87 and see if it makes a difference... Just pulled the ECM and going to a shop to see if they have the MEFI burn or anything to turn off the flag. Will turning it off be bad in the long run? I just looked up my ECM and it's a MEFI 3 (16236999)
08-26-2020, 07:42 PM
#36
Merc Bulletin No. 94-12 is the bulletin I was referring too. Can't get it to upload right now.
Your MEFI 3 DOES NOT DO THE SPARK KNOCK TEST on startup. Your timing issue IS NOT FROM 93 octane gas.
I've run anything from 87 octane to VP110 in my MEFI 1 and it will not flag the knock sensor BECAUSE it is not one of the affected ECMs as stated in the Merc bulletin.
Your MEFI 3 DOES NOT DO THE SPARK KNOCK TEST on startup. Your timing issue IS NOT FROM 93 octane gas.
I've run anything from 87 octane to VP110 in my MEFI 1 and it will not flag the knock sensor BECAUSE it is not one of the affected ECMs as stated in the Merc bulletin.
Last edited by Trash; 08-26-2020 at 07:46 PM.
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jevonlau (08-26-2020)
08-26-2020, 08:07 PM
#37
Merc Bulletin No. 94-12 is the bulletin I was referring too. Can't get it to upload right now.
Your MEFI 3 DOES NOT DO THE SPARK KNOCK TEST on startup. Your timing issue IS NOT FROM 93 octane gas.
I've run anything from 87 octane to VP110 in my MEFI 1 and it will not flag the knock sensor BECAUSE it is not one of the affected ECMs as stated in the Merc bulletin.
Your MEFI 3 DOES NOT DO THE SPARK KNOCK TEST on startup. Your timing issue IS NOT FROM 93 octane gas.
I've run anything from 87 octane to VP110 in my MEFI 1 and it will not flag the knock sensor BECAUSE it is not one of the affected ECMs as stated in the Merc bulletin.
any thoughts on what could cause my timing issue then?
08-26-2020, 08:34 PM
#39
Registered
Your MEFI 3 DOES NOT DO THE SPARK KNOCK TEST on startup. Your timing issue IS NOT FROM 93 octane gas.
My repower by a well known OSO member is a MEFI 3 and had the code 44 show up. Don't know how certain you can be that it is not from high octane. I also cannot say its from the gas, BUT (the big but) you can not get a code that is not programmed into the ECM. If it is turned OFF then it will not show up
It is showing up, so it IS programmed
08-26-2020, 08:40 PM
#40
Disagree again,
My repower by a well known OSO member is a MEFI 3 and had the code 44 show up. Don't know how certain you can be that it is not from high octane. I also cannot say its from the gas, BUT (the big but) you can not get a code that is not programmed into the ECM. If it is turned OFF then it will not show up
It is showing up, so it IS programmed
My repower by a well known OSO member is a MEFI 3 and had the code 44 show up. Don't know how certain you can be that it is not from high octane. I also cannot say its from the gas, BUT (the big but) you can not get a code that is not programmed into the ECM. If it is turned OFF then it will not show up
It is showing up, so it IS programmed
will it hurt to run it if I get it turned off?
