I found this wire cut. Is this the wire to the MAF sensor?

 

That’s not a wire it’s a vacuum line

 

I tried to plug it the other half with my finger but it didnt seem to affect anything at all. Didn’t even feel any suction.

 

That's because the half of the broken line you're holding is the destination half, not the source half.

 

Emissions SMOG tag from an 89 RS:

 

Yeah I meant the other half. The “source” half. I plugged it but it didnt do anything. No suction.

 

Should I replace this line or should I be okay without it?

 

You need it in winter, spring, fall--any time temperature is 45 degrees or colder. Easy enough to splice the broken section with two inches of vacuum hose. You can disconnect and plug in the summer. Or leave it connected all the time, the way GM intended.

 

Makes sense. But what does the “vac motor” and “temp sensor” need this line for? If it isnt a potential fix to my starting problem, then I’m not gonna bother, so that’s why I’m so curious lol

 

It's all part of the Thermac system and heat riser off the exhaust manifold. The idea is that when the temp is cold, heat off the exhaust manifold will rise and enter the intake and help the engine warm up. It's a remnant of the air cleaner that was designed to sit on top of a carburetor. On an EFI engine it's debatable if it helps at all. Plenty of people have dumped the entire air cleaner and not had a problem. If you want to fix it, it's easy enough to fix. If you don't want to fix it, just make sure the port on the throttlebody is plugged. Probably won't make any difference, but the beauty of it is you can try it and see for yourself very easily.

 

Sounds good! Thanks for the info.

 

The thermac prevents throttle icing; and improves fuel economy in cold weather. As I said, if you drive the car at ~45 degrees F or colder, you want it to work. The worst throttle icing happens around 40-ish degrees. The temp is cold enough that the temperature loss of fuel evaporation will put the throttle plates below freezing, but there's often lots of humidity in the air at 40 degrees. The humidity freezes on the throttle plates.

Adding hot air keeps the humidity from freezing, and improves fuel distribution with a cold engine or one that's got blocked or restricted exhaust flow through the heat-riser passages in the intake manifold.

The temperature is controlled by the thermostat in the air cleaner housing that opens or closes the vacuum supply to the air cleaner vacuum motor.