The ski revs freely to 8000 on the trailer and then hangs near 5000 rpm the moment you open the throttle in the water. That description fits a VX110 or VX1100 (2005 to 2015, 1052 cc four-cylinder), and it is confusing because the engine seems healthy on land. On land there is no load, so a problem that depends on load or airflow stays hidden until the ski is on the water.
Limits that are on purpose
The VX has a learning mode (L-mode) that limits power, and the no-wake mode caps rpm as well. Owners report mistaking both for a defect. A limit that is permanently active would normally cap the rpm on the trailer too, so this is not the most likely cause here. Still, it takes a minute to rule out: the live data in the app lists the switch states, so you can see whether the no-wake switch reports on when you did not ask for it. A corroded switch can hold a limit active. The manual explains how each mode is switched off.
An oil-soaked airbox
One VX1100 from 2006 hung at 5000 on the water and revved to 8000 on land. The cause was an air filter housing soaked in oil after an oil change that had been overfilled. It is a single report, but the mechanism is plausible, since too much oil can find its way into the intake, and it explains why the engine only complains under load. The scan cannot see any of this. Open the airbox and look at the filter. If it is wet with oil, check the level on the dipstick with the ski on level ground, remove the excess (pumping it out works) and replace the soaked element. Do the same check after any oil change that you are unsure about.
The electronic throttle
The VX1100 has an electronic throttle valve with paired position signals: the TPS on the valve and the APS at the lever. If the ECU sees the two disagree, it can limit power. Look at both in the live data while you move the lever slowly. They should follow it smoothly and consistently. A jump or a mismatch suggests a contact problem in one of the sensors or their connectors.
The related codes fall in the 112 to 145 range for the throttle drive, 124 to 128 for the TPS and 131 to 135 for the APS. Numbers can differ by control unit generation and by source, so treat the plain-text description in the app as the final word. The throttle valve fault page covers the ETV, TPS and APS entries.
A sensible order of checks
Start with the cheap and quick items: make sure no mode is active, then read the stored codes with the M-JET Diagnostic before clearing anything. Next, watch TPS and APS side by side, and log a short ride to see what rpm does against throttle position. Open the airbox and check the oil level. If all of that looks clean, look at water flow and temperatures, because an rpm reduction caused by heat can feel exactly the same. A reduction because of heat will show in the logged temperature curve.
Blocked airflow, by contrast, shows nowhere in the data. That is where mechanics take over: the filter housing, the oil level, the intake hose, everything the app has no sensor for. The app supports the VX110 and VX1100 in the Sport, Deluxe and Cruiser versions, and the page about rpm stuck around 5000 lists the symptom in more detail.
