Car seems slow, leak test didn't help

[tsibryan]

Okay, here goes. My car seems to have lost power recently, it doesn't rev as fast after spool, and it's reluctant to rev past 4000 or so. I can hear the turbo spool, but the increase in power after spool is minimal. So I figured I had a boost leak somewhere, and I went out and bought parts for a leak tester today. I put a pressure gauge on my tester since there's not a boost gauge in my car. I had the regulator on the air compressor set at 40 psi, plugged the PCV hose and dipstick hole, and aired it up. With 40psi in the hose, my car would only hold 7psi. The only leak I heard seemed to be right on the turbo, but I couldn't feel it. I sprayed some soapy water on the turbo and surrounding areas, and there was a small leak on the compressor housing, but it seemed smaller than the leak I was hearing. I didn't hear any other leaks anywhere along the IC pipes. So anyways, I know my turbo is still spooling, and I can't find any other leaks besides the small one on the housing, so maybe it's something else? My dad, who's worked on cars and sold auto parts part time for like 30 years, suggested that it might be a clogged cat, the 02 sensor, or the fuel filter. What do you guys think? Sorry for the long post, and thanks in advance for any help

 

[ADrewzki]

If it's only holding 7psi, maybe there's something wrong with your wastegate. Do you have a manual boost controller?

 

[tim_korn_99]

If it's only holding 7psi, maybe there's something wrong with your wastegate. Do you have a manual boost controller?

The wastegate is on the exhaust side of the turbo. He should be pressure testing the compressor side. Fix that leak in the compressor housing and then check it again. ANY boost leak is a BAD boost leak, from my experience. If everything is well, you should be able to hold 20psi, and it should only go down very slowly after you remove the air pressure source.
Is there any shaft play in your turbo? A little bit of on in/out shaft play is ok, but up/down shaft play isnt.
-Tim

 

[tsibryan]

How would I fix the leak on the compressor housing? It's on the side of the housing closest to the exhaust side, kinda hard to get to. What would I fill/plug it with? Thanks for the help

 

[Darksyne]

How would I fix the leak on the compressor housing? It's on the side of the housing closest to the exhaust side, kinda hard to get to. What would I fill/plug it with? Thanks for the help

Just to confirm, you did turn the engine over to either TDC or BTDC right? Otherwise most of your pressurized air would just flow through the exhaust.

 

[swarm]

OOPS!

i never knew that -- now i need to leak check again.

 

[tsibryan]

I didn't turn it to TDC. I read in another thread here that the throttle body would seal well enough to check for leaks; that not much air leaked past it. Also on the VFAQ it didn't say anything about TDC? I'd still like to know how to fill a leak too Thanks

 

[Darksyne]

I didn't turn it to TDC. I read in another thread here that the throttle body would seal well enough to check for leaks; that not much air leaked past it. Also on the VFAQ it didn't say anything about TDC? I'd still like to know how to fill a leak too Thanks

If you are only able to pressurize the intake to 7 psi then there is a MAJOR leak somewhere. If you didn't feel any leaks but HEARD a leak by the turbo, then what you heard was pressurized air escaping down the exhaust because your valves were open.

If you turn the engine to TDC or BTDC then the valves close and you can pressurize your intake to find any leaks.

To fix leaks it generally involves tightening either a loose bolt or a loose hose clamp. Im my case I have run across leaks most frequently at my lower intercooler pipe, injector seals, and PCV (which was just removed).

 

[tsibryan]

How can I tell if the engine's at TDC? I hope I don't have to take off a lot of belt covers :thumbdown

 

[Darksyne]

I hope I don't have to take off a lot of belt covers :thumbdown

Nope, all you have to do is point your wheels all the way to the left, pull the circular plug in the driver's side engine cover (in the wheelwell), insert the end of a 1/2" extension into the center of the crank pulley, turn the engine over clockwise with the 1/2" ratchet until the notch on the crank pulley lines up with the BTDC mark on the lower timing belt cover.

Pretty easy

 

[tsibryan]

Yay thank you. Those covers were a pain in the ass when I changed the timing belt. That's good news

bryan

 

[92Talon251]

Your sitiuation seems almost simmalar to mine. Try checking your gasket as well, where your lower IC pipe hooks into your turbo. I had a bad boost leak checked that gasket and I had a chunck missing out of it. I replaced that gasket runs great ever since.