Pat McPherson

I am about to start taring into my little 1999 7.4MPI engine.
After I get it pack together, how do I set the initial timing?
I have read through a manual that I purchased, and it says to put the ECU into maintenance mode to set the initial timing...
Will I need some special tool? Anyone know how this is done?

Dave1972

Hello Pat,

I believe you will need the Merc scan tool for this one. Take a look at RINDA

That is the only way to put the ECM in maintenance mode, otherwise the ECM will try to change everything that you do without being in maintenance mode.

I believe it to be a fairly simple process but hold onto your wallet if you need a scan tool.

RonS

Pat Rinda is the one to contact but you don't have to buy the scan tool. They have a code reader that allows you to put the ECM in timing mode for about 45.00.

Ric232

You don't need a scan tool or code reader. There is a special Merc tool that places the ECU in service mode. It costs $11 - $15 dollars. I'll see if I can find the part#. You can also just short the white and black wires on the DLC connector with a paper clip. That's all the tool does.

Ric232

The Merc part # is 91-805747A 2.

You can get it at www.boatfix.com for $8.75 plus shipping.

Pat McPherson

Thanks Guys!
I ordered the Rinda code reader for $39.95...

crmax

I went the cheap route and bought the 8.75 deal, works great, found out my timming was set at 8 degs when it was new, changes it runs better and sounds better

Ric232

Isn't it SUPPOSED to be set at 8 deg from the factory??