how to set base timing on 5.0 mpi

[wpowell323]

serial number OM603659

This is the newer style distributor with the 6 and 8 in the base. I know to put the pointer at the 8. my question is how do I know if the motor is in the correct base timing? I have installed the distributor with all 3 marks at the based lined up and the pointer at the 8, but the boat doesn't have good power, it is acting like it doesn't have enough timing. The motor ran perfect before I had to replace the distributor. my question is how to check the base timing. I realize the computer controls the timing, but it still has to be synchronized someway so it is close before the computer can work correctly. I saw a link to a PDF explaining how to synchronize the distributor, but the link was no longer working. Don S posted it, if the link can be posted again that would be great.

 

[Bt Doctur]

This is the newer style distributor with the 6 and 8 in the base?????? Please Explain that.
Dist`s are installed with #1 on its compression stroke and at TDC, rotor facing #1 in the dist cap.
Cant get the year for that #, TB IV is points and shoot, TB V grounds a purple wire to get to base timing

 

[burtonrider11]

Does the 5.0 MPI have a distributor? Not being sarcastic, I honestly don't know, but I would have thought that with an MPI motor the distributor would be gone in favor of the the ECU setting the timing.....

 

[wpowell323]

this is after TB. Technically this isn't even a distributor. I think this is actually referred to as a switch. All it does it send fire to the proper plugs. Once the "Switch" is set in the proper position, the computer controls the timing.

 

[burtonrider11]

You may want to try here:

http://boatinfo.no/lib/mercruiser/manuals/mercruiser31.html#/388

It should be in the Mer Service manual #31. You may have to search it, it's 600+ pages.

 

[alldodge]

I have installed the distributor with all 3 marks at the based lined up and the pointer at the 8

It's kind of late now buy why did you remove the distributer just to replace the cap?

If the cap was to be removed, you were to scribe a line on the distributer and block so it can be dropped back into the exact place where it was removed. Now that it's no longer where it needs to be is you need to start from scratch. Bring the motor around to TDC on number one

 

[Tail_Gunner]

There are model numbers on your ecu....computer whatever you wish to call it post them that will point things in the right direction along with the dist you bought.

 

[Fun Times]

I saw a link to a PDF explaining how to synchronize the distributor, but the link was no longer working. Don S posted it, if the link can be posted again that would be great.

Though the attachment by Don S in the following link is for a Volvo Penta, it's the same concept as your Merc but the info is a bit more detailed than the Mercruiser manuals show. http://forums.iboats.com/forum/engi...tibutor-proper-clocking?p=5218875#post5218875

It's about the same theory as setting a normal/conventional distributor as you need to be within a phased ranged setting but without the use of a timing light to set the actual timing degrees.....With this model ECM there isn't a set base timing mode found within the scan tool/ECM.

From mercruiser service bulletin 2003-06....http://www.marinemechanic.com/merc/distributors/mercurymarine/sterndrive/gmefi-nostart.PDF ,,,

Test 2. V8 engines only: If the performance of 1a and 1b (above) does not resolve the problem, bring the engine to TDC (firing). Remove the HVS distributor cap and verify that the rotor is pointing at the correct timing mark, 8, on the HVS housing between the 2 lines shown below. If this is correct, reinstall the HVS cap. Mark a reference line on the HVS distributor and intake manifold (so you know where the distributor was located after you move it in the following step). Loosen the distributor's clamping screw and rotate the distributor 1-2 degrees clockwise (viewed from top), then retighten the distributor's clamping screw. The engine should now run well. If it does not, then you can return it back to the original line that you marked before.

 

[Bt Doctur]

If its what I think it is, you are correct. it only sends power to the plug wires. the spark actually comes from the crank position sensor located in the timing cover

 

[bruceb58]

If its what I think it is, you are correct. it only sends power to the plug wires. the spark actually comes from the crank position sensor located in the timing cover

Spark still gets sent from the distributor.

 

[Bt Doctur]

correct , but dosent originate in the dist. that signal comes from the CPS. Post 6 is the basic install of a dist. there`s no real position
except to have the rotor in between the 2 lines.

 

[bruceb58]

The CPS just tells the ECM where the crank is at. The ECM tells the coil when to fire.

I think we are on the same page basically.