Modern Vespa

I am new to this forum and need help. I just purchased a new 2007 GTV 250 and experiencing the following issues:

Loosing power upon acceleration. Bike starts very slowly, chugging along and then picks up but not full acceleration
Check engine light came on and went off upon acceleration

Some background. After purchasing bike left shop and discovered loose reflector. Returned to shop and back skirt was removed by mechanic to perform the repair.
Left shop and short time later experienced the above issues. My wife purchased a 2007 GTS 250 and I have done quite a bit of riding on her bike and know what to expect performance wise. The GTV comes no where near the performance of her bike.

Reading the forum I saw comments regarding the Lamda sensor and oxygen sensor. Not sure if these are both the same thing but it was the only thing that related to my problem.

The bike is currently at the shop waiting for diagnostics and I am not confident the findings will reveal the problem. I am hopeful but in the meantime would appreciate any input you want to throw my way.

thanks

The lambda sensor and the oxygen sensor are indeed the same thing. The problem you have could be a disconnected lambda sensor (which is one of the things that would cause the light to come on) but I would expect the bike to run at least reasonably well, albeit without quite as much top speed. You haven't listed a location, so I don't know your altitude (which cause the bike to run worse, most likely, with a disconnected lambda sensor).

It could also be something like a clogged fuel injector or a faulty fuel pump. The shop should be able to pull the diagnostic code out of the engine and that should give a much clearer picture of what's going on.

Heard back from the mechanic on results of diagnosics. The oxygen sensor was getting a bad code. They looked at bike some more and found the spark plug wire was loose, hooked it back up to diagnostic and the sensor was fine, no bad code. So now I am stumped. Would the loose spark plug result in a bad reading of the sensor? Also my confidence is somewhat shaken. I don't want to be out and about and have my bike die on me.

thanks

I think the spark plug wire was your problem - happens pretty often. I think your lambda probe is fine. Intermittent spark would cause the exhaust to run rich, which would be detected by the lambda probe.