when I open up my hood while idling, I can hear this subtle hissing noise, pretty high-pitched. I didn't notice it at first but once I caught it, I hear it all the time now.

A few days ago, I attempted to clean my throttle body. I was gonna take everything out but the screws on the ram-air thing didn't wanna come out, so I just opened up the big tube that goes from the air-box assembly to the TB; stuck the straw of my TB cleaner right in there and sprayed it while I had my friend rev it up to 2000rpm or so. I took the MAF sensor off because I thought someone on this forum said to so the engine wouldn't go higher than 2200rpm.

So, did I mess up something there that now makes the hissing noise? Did I introduce air leak where the tube attaches to? I made sure many times that the tube is on the TB correctly and the worm-gear tight. Or am I just paranoid and there's nothing wrong with the car? I think I notice some engine being a little hesitant but then maybe my mind is making that up...

 

I think your just alittle paranoid. Whenever I clean my throttle body (same way you did it) My car gets a little hesitant for a bit cause you gotta wait until all the fluid is out. Then shes fine.

 

But is the hissing noise normal? Oh, and by the way, cleaning out the TB didn't do what I wanted: stopping engine from dying when coming to a stop with the gear in neutral - 2k, 5spd

 

Im not sure what kind of hissing noise your hearing, but if it wasn't doing it before, its definitely something you wanna check with a local mechanic or dealer.

You might wanna check this out
Clicky

And read section *Some additional Info about Throttle Body Cleaning*

 

Cool, thanks a lot for your help.

 

No problem