Modern Vespa

My English is poor. Sorry.
It only works at low speeds. It's like the seat sensor is working.

The throttle body is taken from a working model.
I replaced it but it didn't fix the problem. I replaced the master key and it worked fine.
I also borrowed a seat from a working car and replaced it. No change.
The roll lock is normal. O2 sensor replaced, water temperature sensor replaced, ECM cleaned, speed sensor is a used replacement and works fine. Injector replaced with a new one, ignition coil replaced with a new one, plug wire new, plug cap new.
If you open the throttle, you can reach 120km/h. It has power. It only misfires at low speeds and is out of order.

Fuel filter and fuel pump ever been replaced?

Used, 42000km, not replaced yet. Fuel pressure is 2kg, the specified value. I don't know about the low speed range, so I'll try it.

Before jumping on fuel pump/filter, verify you have no vacuum leaks.

Low rpm/poor idle usually points to unmetered air being sucked in.

There is no secondary air and the engine starts and idles normally. The only problem is a misfire at low speeds.

For now, the idling is normal, the seat sensor is released with the center stand, and the engine runs smoothly when I turn the accelerator. So it's probably a sensor or wiring.

When I put the center stand up and opened the throttle, the engine turned fine. When the wheels were turned, the misfire only occurred at low speeds. I replaced the speed sensor with a new one, and the roll lock unit was used, but the problem did not improve. I also replaced the immobilizer antenna, which was in stock, but the problem did not improve.

Speed sensor new

After that, I replaced the roll lock ECU but it didn't fix the problem. Today I replaced the pickup coil and it was completely fixed. I hope this is helpful.

The problem has recurred. It suddenly malfunctions. After repeatedly replacing the unit, it suddenly started working normally again.
The only thing that concerns me is that the type of ECU I have is slightly different. When I use this particular ECU during a malfunction, it behaves differently.[img][/img]