00-Z28

iTrader: (1)

Hey guys, I need help trying to figure out what this problem is. I was merging on the highway a couple days ago, I wasn't WOT or anything, but I was giving it gas to gain speed, then the car seemed to suddenly lose power and at the same time I heard what sounded like a hissing sound coming from the driver's side. Under light load the hissing was less noticeable, but the more load on the engine the louder the hiss became, not changing in tone though. In park the noise isn't nearly as noticeable, but you can still hear it. It sounds like it's coming from the front of the engine somewhere near the power steering reservoir, but it's hard to tell.

It's been running like this ever since that day merging on the highway, it hasn't really changed. My vacuum at idle is just under 19 in/hg, which i think is supposedly normal, so I don't know what the problem is. My cats have been giving me problems recently, rattling and such, so maybe the exhaust is partially clogged? The car isn't overheating or anything, but maybe it increased pressure? I re-torqued the studs on the driver's side headers and everything was as tight as it should be. Any advice will be much appreciated.

G Atsma

The hissing might be from a clogged converter, which would explain the loss of power. Pull the drivers side converter and see if the problem goes away. Is the noise from the front or rear? If the rear, a clogged converter it is....

00-Z28

iTrader: (1)

The noise sounds like it's coming from the front near the power steering reservoir, but it's hard to tell because it's not really loud like it is when the car is under load.

Darth_V8r

iTrader: (4)

If you can get it to do it at idle, pull the oil cap and see if the hissing stops. Might be positive crankcase pressure due to failed PCV

garygnu

also check for a vacuum leak at the intake ports ,mite need new intake gaskets .

kossuth

iTrader: (12)

00-Z28

iTrader: (1)

I pulled the oil cap while running and the problem still persists. I'll check the intake bellow as soon as I can. The seals on the intake manifold should be fine because they're felpro gaskets that have been on the car for maybe 2 years/8k miles, so I can't see why they would suddenly give me problems, but I could check them out too. What do you guys recommend, unplugging the IAC and using an unlit propane torch? I know some people use carb cleaner, but can it damage the rubber gaskets?

It seems to make the most sense that the crappy cats are clogging the exhaust a bit and the added pressure is causing a leak, but I don't know for sure. I have the new Y pipe waiting to be installed, so I'll try and get that done within the next two weeks and I'll change the header gasket again while I'm at it. Thanks for the ideas guys. In the meantime, if anyone has other thoughts on potential causes please let me know.

kossuth

iTrader: (12)

I doubt you have a clogged converter etc. Sounds like a vacuum leak to me. Could try an unlit Propane torch. I've never had any luck with that method unfortunately. I've always used carb cleaner or brake cleaner in and around the sealing surfaces. That will give you a good idea if you have a leak in that area. Don't use starting fluid. While it would do the same as carb cleaner/brake cleaner it is more volatile will flash alot easier.

KerrRoofingSC

Did you figure out the problem?

LilJayV10

iTrader: (39)

have you datalogged it? If your fuel trims are adding a bunch of fuel, you probably have a vacuum leak.

Full Power

It's been six years, either solved problem, blown motor, or project abandoned.