Clanton

It failed the emission test at 15 mph the max was at 56 and the meas was at 100 the 25 mph passed but the 15mph did not anyone know why?

4Driver4

I can't read that thing.

CEL on?
Old oil?

Looks like it might be an HC issue at idle, indicating old oil.

AudiMick

Agreed change the oil and filter and try an "italian tuneup".

turbo510

Yep, take a better picture next time, or just type what the numbers were. Does anyone know why? Well, for starters were there any emission fault codes? Were the "rediness" items all set? You'd need at least an OBD2 scanner for that. You could have old oil full of combustion blow-by, as 4Driver4 said. Could be the catalytic converters are not working well, maybe lazy O2 sensors, a faulty coolant temp sensor, leaky injectors, worn spark plugs or defective plug wires, low compression, etc. Does the car idle smoothly and start/run well? I'd change the plugs, replace the coolant temp sensor if its more than a few years old, run Chevron Techron fuel system cleaner through a tank of gas, then change the oil. Accelerate it wide-open, where its safe, a few times before the smog test.

I couldn't see it on your fuzzy pic, but usually the '96 will have a clogged EGR passage, and won't pass the nitric oxide (NO) requirement.