[ischmitz]

I would doubt it. You'd have to open the engine lid and listen. Also do not confuse the whine of the fuel pump with the CDI box whistle. In terms of absolute loudness there is quite a spread between boxes so this is not a good or reliable indicator for the box working.

I have seen boxes that latch up and can only be "reset" by shutting off the car. They ususally overheat when this happens.

On another note the box under the passenger seat is NOT the CDI box but the control unit for the frequency valve. If there was water on the cabin floor you have a good chance that there was damage to this box resulting in poor mixture. This could be the cause for poor running.

Good luck,
Ingo