5.7 EFI base timing

Discussion in 'Gas Engines/Drives/Transmissions/Props' started by Strecker25, Jul 8, 2019.

  1. Strecker25

    Strecker25 Well-Known Member

    Nov 20, 2014
    Rochester, NY
    1998 290 Sundancer
    Twin 5.7EFI/Alphas, Kohler 4kw
    hey guys, just a quick check. For timing our 98 5.7 EFI motors the manual says to put it into service mode by jumping A and B on the dlc. I did that, and it clearly locks timing (rough to start but it catches after a couple cranks)

    I only have one mark on the timing cover, which much be the 8* BTDC the manual calls for in base mode. The video below shows it after I set timing, I’m still a hair advanced I think, but can someone verify I should be timing to that mark while in service mode? Just making sure I’m understanding the manual correctly.

     
  2. Wanderer 290

    Wanderer 290 Member

    30
    Jul 1, 2019
    01 sea ray 290 sundancer
    Twin 5.7 b3’s
    I suspect that the mark you see on the harmonic balancer is 0degrees advance or top dead center.

    If you look closely at the harmonic balancer you should see small degree marks in incrcrements of 2 degrees.

    The video indicates the timing is set at nearly 0 degrees which is retarded and will cause a very rough running condition.
     
  3. Strecker25

    Strecker25 Well-Known Member

    Nov 20, 2014
    Rochester, NY
    1998 290 Sundancer
    Twin 5.7EFI/Alphas, Kohler 4kw
    Interesting, they ran like absolute tops set there. I’ll take another close look at the balancer and see if there are more marks but I swear I didn’t see anything
     
  4. Bt Doctur

    Bt Doctur Well-Known Member

    Aug 21, 2010
    New Jersey
    Ex SRV 240 Weekender twin
    in between
    IGNITION SYSTEM SERVICE MANUAL NUMBER 24
    Page 4B-6 90-861327--1 OCTOBER 1999
    EFI / MPI Models
    1. Connect timing light to number 1 spark plug wire.
    2. Start engine and run at 1300 rpm until it reaches normal operating temperature.
    3. Stop engine and connect the scan tool or timing tool to the DLC connector on the EFI/
    MPI wiring harness.
    4. Start engine, allow rpm to stabilize.
    NOTE: MEFI-1 models only, manually adjust remote control throttle lever to get 1200 engine
    rpm.
    NOTE: MEFI-2 and MEFI-3 models only, ECM will automatically adjust engine rpm to
    approximately 1200 rpm when put in the service mode on a scan tool or when using the
    timing tool.
    5. Check ignition timing. If incorrect, rotate the distributor until timing is correct. Torque
    clamping screw to 18 lb-ft (25 Nm).
    6. Recheck ignition timing.
    7. Disconnect scan tool or timing tool from DLC connector.
    8. If required, return remote control throttle lever to idle position and shut off engine.
    9. Restart engine, increase rpm to 1300 then return to idle position slowly. Ensure that
    engine returns to idle rpm. Readjust throttle cable, if required.
    10. Shut engine off.
    Spark Plugs
     
  5. Strecker25

    Strecker25 Well-Known Member

    Nov 20, 2014
    Rochester, NY
    1998 290 Sundancer
    Twin 5.7EFI/Alphas, Kohler 4kw
    Thanks Bt. I have that manual and that’s the procedure I followed but I guess my mistake was to assume the V notch on the cover was 8*. The white V is the only mark there from what I can tell though, but is it 0*?

    I ordered a timing light with advance so that might tell the story. Just seems we’re merc only put a single mark
     
  6. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass, cape coral fl
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    That mark is 0 degrees. Advance your light the 8*
     
    Strecker25 likes this.
  7. Strecker25

    Strecker25 Well-Known Member

    Nov 20, 2014
    Rochester, NY
    1998 290 Sundancer
    Twin 5.7EFI/Alphas, Kohler 4kw
    Thanks all, timing is now spot on at 8* BTDC in base mode.

    I’m getting no-load advance at 2400 rpm (just in the slip) of 36* which seems a little high. I’m looking for the timing curves to verify what it should be.

    I also have the engine gateways which report 36* of advance and that matches exactly the “real” advance including base timing that I’m seeing so I think the computer is behaving properly
     
  8. Wanderer 290

    Wanderer 290 Member

    30
    Jul 1, 2019
    01 sea ray 290 sundancer
    Twin 5.7 b3’s
    36 sounds about right for a small block Chevy. No load and with load should be the same unless the detonation sensor detects ping in which case the computer will retard timing until the ping is not detected. You should notice an improvement in fuel consumption too.
     
    Strecker25 likes this.
  9. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass, cape coral fl
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    With no load it can easily hit 40*, no worries. And 36*, under load might be good for your hot rod street car but not the boat.

    Just drive it, Mefi-3 knows what it wants. :cool:
     
    Strecker25 likes this.
  10. Wanderer 290

    Wanderer 290 Member

    30
    Jul 1, 2019
    01 sea ray 290 sundancer
    Twin 5.7 b3’s
    You are correct! I should not have said” under load”.
     
  11. Wanderer 290

    Wanderer 290 Member

    30
    Jul 1, 2019
    01 sea ray 290 sundancer
    Twin 5.7 b3’s
    Actually should not have said “ with load”. Opps!
     

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