Figured I'd go get myself a haircut today, and as I pulled into the lot, the car started idling rough and the tach bounced around a little. As soon as I parked the engine quit on me. I turned it back over a few more times and it would just idle rough and die. Fast forward an hour, I go back out and the engine starts and stays running. Idle is noticeably low at around .5k and shudders around. Oil pressure seems high, 60psi at 2k. And I'm losing power. I keep the gear high and RPMs low on the drive home.

Open the hood, clean the MAF, check the intake seals, and check the TB. All seem fine. On the left side of the block, although, I hear a faint hissing noise which I can't pinpoint for the life of me. Car doesn't throw an SES either. Are these typical symptoms of a vacuum leak and are there any common specific points of failure in the vacuum system I should be looking for? Thanks!

 

Yeah, sounds like a vacuum leak. Get a small propane bottle with a nozzle and let the propane leak around the area where you hear the hiss. The location where the car stumbles or dies when you pass by with the propane is the place where the leak is.

 

I'll try to figure out where it's coming from. I've also seen that the PCV valve makes a hissing noise normally? Maybe that's what I'm hearing.

 

Take the PCV out and give it a shake. If the rattle's dull, either clean it out or (better), replace it with an OEM part. They're so cheap, it couldn't hurt.

 

You don't need to get a propane tank.

add a small amount of dish soap to water, class cleaner will work in a pinch, spray or pour the soapy water on areas of the hoses and watch for bubbles to start forming. That will show you the air leak.

 

Better still, just use a hand pump with a gauge. It'll tell you if there's even a vacuum leak in the first place.

 

Mother of god DO NOT DO THIS. You will suck in the dish soap and water into the engine. (This works great for finding a pressurized leak though i.e. finding the leak on a tire) Get some carb cleaner or starter fluid and spray around the vacuum lines with the car on. when the idle jumps up that's where your leak is.

 

I recently installed Kinetix V plenum and the nwp throttle body and I hear the hissing from left of the block as well and cannot find where it's coming from, although my car doesn't run as bad as you mentioned, it will idle low and struggle occasionally at idle. I replaced a hose and threw some silicone sealant over stuff in hopes it would help lol... unplugged battery overnight and didn't help anything, and now my throttle position sensor isn't reading anything (using Torque Pro app) but that doesn't seem to affect anything necessarily. Torque also reads a Vacuum of 25-26psi if that helps. Hope I get some help, I'm not trying to drive on this so cars been sitting for awhile