On my 7.4 454 MPI with MEFI 3 , I hooked up a Fox Marine gateway and discovered an odd timing issue. At WOT above 3000 rpm, I seem to read only 17 degrees of timing advance. The total timing should be 32-34 degrees, so if I subtract the base timing of 8 degrees I should be reading 24 degrees advance through the ECM, not 17. I have no codes, no warnings etc. While monitoring the timing as I am accelerating, I never see it above 17 degrees, and it is not detecting any knock. I am going to recheck the base timing but I suspect it is ok, so I am not sure where to go next. The engine seems to start and run fine, although I am down about 3-5 mph from ideal top speed. Any suggestions on next steps ?

(moved to General section)

1. Has the ECM ever been tuned to your knowledge?

2. Are you getting this data while under load and on the water or simply logging while on the trailer?

3. Without looking at the table values within the .bin file it is tough to say what is going on. I suspect the unit is not pulling the correct data IF the ECM has not been touched. Also remember the timing curve in a MEFI unit is 3 dimensional and not a simply line or curve. Stock MEFI 1 had 40 degrees of advance at 40 kPa on motor decel.

Thanks for the info- I moved the thread to the Technical section. I am 2nd owner of this 2000 with L29 454 in 2006, and the ECM has never been touched while I have owned it. Possibly it could have been done by the first owner.

Thread moved to here- 7.4 MPI, MEFI 3 odd timing problem