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TPS Setup and Throttle Balance Tuning

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For the following V11 Moto Guzzi motorcycles, made from 1999-2006
V11 Sport, Le Mans, Rosso Mandello, Scura, Tenni, Cafe Sport, Rosso Corsa, Nero Corsa, Naked Ballabio, and Coppa Italia.

Be certain the valves are in adjustment while the motor is "stone cold." Good results are found 0.006"(0,15mm)/0.008"(0,20mm) intake/exhaust. Install fresh spark plugs, properly gapped. Ensure that the fuel and air filters are in good condition and the intake air flow is unobstructed. Using a throttle body cleaner and appropriate nylon brush or such, clean the throttle bodies and butterfly plates to ensure they close fully without restriction. Remove the air bleed screws and clean them along with the holes they fit in.

Calibrate the Throttle Position Sensor (TPS) to 150 mV with the right throttle fully closed as follows:

Disconnect the synchronization rod at the ball joint on the right side (the side with the TPS sensor), back off the right throttle idle screw using a 2.5mm hex key, and back off the "choke" cam (make sure the choke cable permits full retraction of the cam.


Be certain your battery is well charged. Turn on the ignition key, but do not start the bike. Measure the voltage difference between the two outer wires of the TPS.  If the voltage is not 150 mV , then loosen the TPS clamp screws and gently rotate it as required. Changing the fasteners to standard hex drives simplifies the process (4mm/0.7 thread pitch x 17mm long). Be careful not to force it against the TPS’s internal stop in the direction of reducing the voltage, which could damage it. Plus or minus 5 mV can be obtained with a little effort. The reading wanders as the fasteners are tightened, so a few attempts will finally bring it into spec.

To do the next step, you will need to connect a vacuum manometer (mercury sticks, "TwinMax" device, or similar) to each of the two ports on the intake fittings next to the cylinder head. The vacuum taps may be capped or connected to hoses, which are temporarily removed.

Next, close both air bypass screws, reconnect the synchronization rod, but keep the right throttle idle screw backed off to put the connecting rod in tension, removing any backlash. Start the engine and balance the throttle body vacuums at idle using the synchronization rod adjustment. Screw in the left throttle idle screw if the idle is too low to maintain. Do not use the choke for this purpose, because that would put the connecting rod in compression, introducing backlash, causing the throttle bodies to go out of balance. Best sychronization may be obtained at operating temperature especially for bikes operated in hot climates. Keep a fan blowing over the front of the motor if it is to be running for any length of time.

Now adjust the left idle screw for a TPS reading of 0.521 volts. +/- 0.011 (corresponding to 3.5 +/- 1.0 degrees physical opening, as read by the digital diagnostic software). This accuracy can be obtained with a little effort. (Some riders have been known to also subsequently physically readjust the TPS (not the idle screw) to lean or richen the entire throttle range. However, while offsetting the TPS to a higher voltage will fool the ECU into adding more fuel, but it will also affect the ignition timing table. See also the note at the bottom under “Options”)

Next open both air bypass screws to obtain the idle RPM at 1100 to 1200 while maintaining balance. Air bypass screws should be open 1/2 turn or more. If not, back off the idle screw to reduce the TPS voltage reading in steps of 15 mv and open the air bypass screws to compensate until they are opened 1/2 turn or more.

Check balance at 2000 - 3000 RPM as follows:
A When checking balance at 2000 - 3000 RPM, make any fine correction needed using the synchronization rod adjustment, then:
B. Check balance at idle RPM. If OK, go to step C, if not, rebalance at idle using the air bypass screws, and go back to step A.
C. Disconnect the voltmeter and manometers. Replace any hoses or caps that were connected to the two intake taps.

D. Reset the choke cam and cable to provide an appropriate idle increase when engaged without the cam making contact with the lever off.

That completes the procedure.

Once this procedure is completed successfully, future minor changes in idle speed can be made simply by adjusting the left throttle idle screw. Since the throttle bodies have been balanced, backlash between them has been eliminated, and air bypass screws have been properly adjusted to maintain balance at idle, these should be stable for many miles.

Use a gas analyzer if available to set the %CO level.
Use a diagnostic tool or diagnostic software such as Axeone, TechnoResearch's VDSTS, or Guzzidiag to adjust the fuel trim (CO), check throttle angle, RPM, and more.
The setting of .521 volts is in the middle of the range of published settings, and has been found to be reliable for stock motorcycles. However, for those who wish to follow specific instructions in their aftermarket parts, Moto Guzzi owners or service manuals, particularly for modified motorcycles, the table below shows the TPS voltage corresponding to various opening angles per the Magnetti Marelli OEM TPS specification. For other settings, here is the formula: 0.1061 volts/degree + 0.150

Degrees Volts DC
2.9 .458
3.4 .511
3.5 .521
3.6 .532
3.8 .553
4.0 .574
4.1 .585



Measure the TPS voltage at the outer two wires or TPS contacts. There are many different methods:


1) Use a Breakout Harness for easy accurate access.

2) Backprobe the ECU connector (especially on early V11 with the connector on top of the ECU).

3) Disconnect the cable connector from the TPS. Use two short lengths of thin stranded wire of about 30 gauge. Strip about 1/4-3/8 insulation off the ends of the stranded wires, insert a stripped end into the connector, and push the connector in part way, far enough to make electrical connection, but no need to jam it all the way.

4) Follow the wires up under the seat, splice, solder, and insulate in some lines with female bullet connectors for easy probing.

5) Probe at the TPS connector, as shown in this image that Mike Stewart graciously provided:

These instructions are the product of many people.
It was composed in this thread:
Originator: Ryland3210
Principle investigators and authors: Ryland3210 and dlaing
Contributors of useful technical information: docc, BrianG, Guzzijack, luhbo, motoguzznix, pete roper, Greg Field, Jeff in Ohio, MPH motorcycles, and Jaap (for defending our thread against extinction).

Edited June 17, 2014 and again September, 2014 /  docc

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