MAGNETI MARELLI
If you own an Evolution Harley Davidson with fuel injection or a 1999 to 2001 injected Twin Cam, you are unfortunate enough to own a Harley with the Magneti Marelli fuel injection throttle body system. These injection systems can be very temperamental especially when it comes to cold or hot idle (or both).
It is possible, however, to correct a poor idling condition by resetting the throttle position sensor on these induction modules. This procedure will typically correct cold and hot idle or, at least, make a positive improvement in engine idling speeds. We hope this helps some of you who may be frustrated with their Magneti Marelli system.
Begin with the air cleaner assembly removed from the motorcycle:
•Unplug the idle speed control on the top of the throttle body.
•Back off, but do not remove, the cold idle screw.
•Back off the hot idle screw. *Note how many turns the screw is turned counter clockwise* The butterflies should end up being completely closed.
•The throttle position sensor plug has three wires. Insert a metal test pin into the wire on the right side. The correct wire is grey with a purple tracer.
•With a multimeter set to DC voltage, connect the red lead to the test pin and the black lead to a good ground. Preferably, the negative battery post.
•Turn on the ignition switch. Make sure the RUN/OFF switch is toggled to RUN. The reading that you will be aiming for is .275 This BASE POINT reading tells the computer that the throttle plates are completely closed.
•Achieve this reading by loosening the set screws on the throttle position sensor. Slowly move the sensor until the reading .275 is achieved. It is difficult to lock down the sensor without having the reading change. It is very sensitive. It often takes a number of attempts to get this step completed correctly. Be prepared to practice patience here.
•Once the reading .275 is achieved and the throttle position sensor is locked down, we move on to the COLD IDLE SETTING. Turn cold idle screw clockwise until the reading .650 is achieved.
•Electronic adjustment is complete. Turn off ignition switch. Remove test pin & multi-meter. Plug in the idle speed control and turn in the hot idle screw to its approximate, original position.
•Start the motorcycle and adjust the hot idle screw as needed, especially after reaching full operating temperature.
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Air Cleaner Removal & Throttle Cable Removal & InstallCustom Air Intake Install
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I'm installing one as we speak, is there and spec on correct installation?
I've adjusted tps to .275 and set the cold idle at .650. When I plugged in the control actuator and turned ignition back on and run/off switch back on the actuator doesn't move in or out and it's brand new? Can it be the cruise cable is too tight and closed the circuit? My cruise stopped working also
I’ve had no problems with MM. A couple times I’ve had a high idle situation but it has fix itself and all is good. Got stage 1 and retuned back in early 2000s. Was told by mechanic if you start hopping these MMs up that’s when trouble will start.
I bought a 2000 road king it's turns healthy I cleaned the plugs emptied the fuel tank it was sitting five years I can't get no spark is it the coil or rectifier I'm really lost with this it cranks over healthy lots of compression can you give some help pointers so I can at least get it running I live in Chicago I have to drive it 50 miles in 35 degree temperatures please help me out premium member JEFFREY DENIS.
Good article. Believe it or not I actually get along ith MM. At the time the biggest problem, in my opinion, the machanics did not understand it. Carbs seemed so simple. Delphi is just as complicated, but It as less tempremental, I guess the natural progression from carb to injection had to take this step. Fuel injection has been very very good for Harley. Especially in cooler regions. Easier starting , hop on it and go, no icing trouble free for many miles. The problem MM has today is Parts availability. If you convert it my choice ould be Thunder Max.