How to obtain the widest pulse on an oscilloscope?
Just in case your DSO doesn't have a pulse width trigger setting consider the following.
A square wave at 112 kHz with 50:50 duty cycle has a mark or space duration of about 4.5 us. Looking for a mark or space of 1 ms is easy if you feed the signal to the scope via a low pass filter and trigger on amplitude. The low pass filter can be set arbitrarily between 1 kHz and 10 kHz and you will definitely get a much bigger amplitude when the pulse length extends this much.
Here's a picture that explains: -

(source: evalidate.in)
So you get the trigger and you can measure the length on the scope because you said it was a DSO.