Modern Vespa

My scooter is a 2023 Vespa GTV 300.
When doing top speed run, around speed 132km/h (82mph), the CEL was blinking, but the scooter runs fine without any hesitation, just the CEL was blinking like 1hz frequency.

When I slow down to 120km/h or lower, CEL stopped blinking. (also not light on, just like nothing happened).

The only archived code is P0301 which says engine misfired detected. But it does not imply that happened during top speed run, simply means it happened. And if I turned the scooter off completely and restart it. No code is stored and can be read out.

It does not look like a rev limiter kick in, scooter runs fine and smooth when CEL blinking.

I had my ECU top speed limiter raised to 200km/h, the RPM limiter raised to 9900rpm.

I run a 13 inch wheels front and rear and the Speedo is 100% match with GPS Reading, 132km/h on the clock when 132km/h on the GPS.

Could be as simple as bad petrol, or fuel pressure check petrol cap is on ok

Curious, what rpm had you reached at 132kph when the cel light was blinking?

I have no idea which RPM I was at....2023 GTV does not come with a tachometer.

I have the following mods
1. Polini Primary gear (202.1413)
2. Malossi Multivar 2000 variator kit (Runing with 3 x 16g +3 x 17g)
3. ECU reflashed by myself.
4. 1o1 Factory 13 inch rims front & rear.
5. Akrapovic exhaust (With CAT) and a catless front manifold.

based on the "Piaggio Quasar Gearing Calculator"....
with Polini primary and Piaggio secondary gear...
When Running at variator ratio 1, 131km/h should be working at 9600rpm which is lower than my RPM limiter 10000rpm...

But it is hard to know the precise variator ratio when runing at certain speed.
Probably need to add a standalone tachometer to the scooter.....

Well after changing all that you would have to expect something... what spark plug are you using and the fuel pump and injector can only handle so much and something has to give.

I have full stock ignition system and fuel system, that means the spark plug, spark plug cap, conductor, coil, fuel pump, injector, all stock.

I did not radically change the fueling and ignition. Raised RPM limiter, raised speed limiter. Slightly increase the ignition advance for better throttle response. The target AFR is not changed in most area.

My next move would probably check front spark plug to coil....

I suggest either:

Install the optional PMP3 module and then use either Piaggio's MIA app or my Vespa Snoop app to record the RPM.

OR

Get an ELM327/ODB2 bluetooth module and then use an app from the store - most can record.

pull the injector out and remove the basket filter then, i would seriously look at the spark side of things.

Sorry, it's been a while and I forgot to update the result.

When I doing my ECU reflash, I did not aware that the ignition table only goes to Max 9500 rpm, and I set the Engine RPM limiter to 10000rpm. I originally thought that Malossi piggy back ECU has unlock the top RPM to 10500rpm, so my 10000rpm should be ok.

But I don't think too much about the ignition timing between 9500 rpm and 10000 rpm, since there is no timing setting for this area, it is unpredictable of the ignition behavior. I was originally assuming that it will run last known ignition timing (9500rpm) while obvious it is not. It actually does not reach my limiter setting (10000rpm), but goes beyond 9500rpm for a certain time without ignition timing setting and will cause the check engine light blink, the error code is engine misfire detected.

I finally figure it out and lower my RPM limiter back to 9500rpm and no more check engine light blink. Of cause the top speed drop from GPS 135km/h back to 132km/h.

Makes sense. Thanks for letting us know.