Hitting max boost, but car goes no where..

[PieEyedPiper]

It only happens when its hot, or after I've been boosting the whole way across town. I'll be around 2k rpm, and I'll wanna giver some gas so I do. I hit max boost ~14lbs. and the car just doesnt go anywere. It's fairly intermittant.

I don't think its a boost leak cause I can pressurize my intake to about 18-22psi, which is defintiely above my current boost levels.
I also have low compression on 2 cylanders. going from passenger side to driverside.
180 181 149 151

Hope thats enough info for ya.

 

[oldman]

The two of you are really out of control with these long posts. !

 

[VBGSX]

Now that's the kind of quality test I like to see

Oldman. Hey, hey, hey, bite your toungue. I'm still the champ of Long Posts. DSMLP Champion

1. Compression is good
2. As we all know, the 2g BOV leaks. Your's is terrible. You are loosing 5psi(minimum)
Time for a new BOV
3. You're loosing 1psi between your turbo and IC. You could be loosing it through your turbo seals or in the pipe between the turbo and the IC. Since you heard bubbling, it's probably your turbo seal. Not a worry unless you're smoking. When the car is running, you won't be loosing the 1psi because the oil pressure in the turbo is higher than the 1psi pressure.
4. since you've tested past the turbo and still have air pushing out of the crankcase, it probably getting past either your valve seals or compression rings.
5. When you pressurized past the turbo, I hope you sprayed soapy water all over the injector seals, TB gaskets and vacuum hoses.

I also found that if I disconnected my tube going from the PCV to the Mani. I built ZERO Pressure. If I reconnected the line I built pressure.
.

That's because you were supposed to cap off(vacuum cap works) the plug on the intake mani when you disconnect the PCV line from it..
If you're building pressure, then it's probably ok though.

After looking at all your info:
Let me go back to basics for a sec. The only way your wastegate will open, is if it sees the pressure needed to open it. An example would be if you have a 12 lbs wastegate spring, the only way it will ever open is if it sees 12 psi. If your wastegate doesn't see the 12psi, it stays closed. This allows your turbo to keep spinning more(faster) and more(faster) until the wastegate sees 12 psi.
With all your leaks, your turbo is working harder and less efficiently than it should have to. A simpler way to look at it....If your loosing 2psi out a leak, your turbo has to make the 12 psi and make up the 2psi(now 14psi) so the wastegate see's 12psi.
You could definitely overspin and overwork your turbo. There will come a point when your turbo can't make up enough(since the t25 is so small)
At the same time your ECU is seeing all this extra air being drawn in and it's adding the appropriate fuel. Since you're loosing a lot of metered air, you're also running rich because the ECU doesn't know you're loosing the metered air.
I hope this makes sense. I'm trying to write it in the simplest terms

so:
leaks cause turbo to work harder/more hotter charge/rich condition/more knock prone.
It will also help to heat soak the IC and heat up the engine more.
And as it's already been mentioned, you're probably heat soaked from "boosting all the way across town"
Fixing all your leaks will help you run a lot better.
Good luck

 

[PieEyedPiper]

I hate to bring this thread back to life.. but its just so much fun!

Just a follow up and one more question for you guys.
I replaced the PCV with an OEM valve and retested my system. I also rocked the car back and forth while in gear to find the sweet spot to build a nice amount of pressure (i really think this part should be added to the vfaq.).

At the turbo: I built 11psi max. (with plugged bov, cause bov leaks at 5psi.)
I heard bubbling. This must mean turbo seals.

At the TB: I built 20psi max. NO bubbling, MINOR hissing sound from under oil cap. and the pressure took over a minute to go abck to zero after I shut my compressor off.

My analysis of these latest results indicate that my rings are good, and afaik valve guide seals are good as well. (These were concerns previously)

The bad news is that my turbo seals leak. Now I've read that while operating this leak is probably minimized to some extent due to oil pressure. This is a good thing. But is there anything I can do to try and fix this issue? Is there a sneaky bolt I can tighten up to limit the amount of escaping pressure?

All in all, I want to thank everyone who helped me in this and past threads. I've gone from needing a new motor to really only needing a new BOV (which every 2g owner does).

Cole Burns.

 

[oldman]

Glad you got to the bottom of it...and became a leak test expert in the process. 30* before or after TDC is a good place to be for leak testing, no valve overlaps. I don't think there is an adjustment screw for the 2G BOV, your best bet is a 1G BOV. As for the turbo seal, just pay attention to your tail pipe under boost, any hint of smoke and you should know where to look first. Happy boosting.

 

[VBGSX]

Don't worry about this one coming back from the dead.. This one has a lot of good info that can also benifit others.

As I posted above, don't worry about loosing the air at the turbo. The oil pressure will be higher on the other side so you won't loose the air pressure through the seal. As Oldman has stated, just watch for oil consumption and smoke out your tailpipe. If you see it, like he said, you'll know where to look first.
Definitely replace that 2g BOV. I think you'll notice a big difference all around once it's done.
Glad you figured it out.
Good luck