Been searching but can't seem to find anything.. Evo IX MR.. Went out and started the car.. Idled high thought okay its cold all good. Well in traffic the idle stayed erratic was around 2k rpms sometimes it would dip down but was high. As driving I heard a loud hissing noise. Sounded like a leak.. I got home popped the hood and sprayed the TB down as well as the intake manifold. I can't see anting bubbling. But the hissing is really loud. Idle and AFR's are all out of whack. But the car holds boost.. That is what has me a bit confused. I can do a pull and it holds boost and pulls fine. Hissing noise is loudest back by the intake manifold. I smell some fuel when I go WOT but not sure if that was always the case or something new. I don't drive the car everyday. I looked at the injectors and fuel rail and didn't see any thing wet or leaking. I know I need to do a boost leak test but wasn't sure if anyone had any suggestions due to the fact that the car does hold boost.

Would an injector seal hiss like this? Sound like an awful vacuum leak.. Just not sure what else to look for..

 

Try spraying around the injector seals. It could be fuel is leaking out of the seals under boost and since fuel evaporates quickly, you don't see any residue anywhere. Even if you don't find any bubbles, it's not hard to pull the injectors out to inspect the seals.

 

Thanks. Going to do that now. Would bad seals cause that loud hissing noise?

 

Update. Pulled the fuel rail and injectors. Ripped lower seal. That is what the hissing noise and erratic idle was from.