Unknown Boosting Problem

[afireinside5976]

Well this has been going on now for about a month, and I have tried about everything I could think of to try and fix it, but I still haven't found the problem.

My mods are:
Big 16g
6 bolt swap
Dump Tube
2g exhaust mani
Front mount & piping
K&N Filter
Boost guage
Crappy air/fuel gauge (it was free)
Turbo Xs Boost controller
Turbo Xs Blow off valve (not recirculated, it wasn't when I got the car and haven't had any major problems with it that way)
NGK6's

All MAF honey combs are in

About a month ago I was driving along and noticed my BOV was not as loud and the turbo was spooling slower. I didn't even mess with anything and the day before it was fine. I was running 14 psi and it dropped (I cannot remember what it dropped to), but now even with my boost controller cranked all the way down I can only get about 15 psi max.

This is what I've checked so far

Boost leak test: Checked from the turbo to throttle body, and from throttle body to where ever. Both times only little small leaks, fixed them though. I pressured it at 20 psi and it dropped about 1 psi a second,

Compression: 168 170 167 170 across the board

Tried running straight waste gate to see if it was the boost controller, that wasn't the problem, still only got 15 psi

New plugs

I'm throwing no codes

I'm burning some oil, but I have a very small leak in the oil feed line, but there is no oil inside the turbo

Exhaust and intake fins on turbo are not bent or damaged.

Exhaust leaks: I may have a few small ones before the turbo, but was like that when I got the car and haven't fixed them yet because they aren't going to be fun. There are only 3 bolts holding the turbo to exhaust mani (one broke off inside) and two bolts that bolt the exhaust mani to head are stripped, but none of that effected anything before, still need fixed though.

Wastegate: now this I'm unsure of, I have a dump tube and at a idle there is exhaust coming through the dump tube, and I don't think it should be. The wastegate has 3 washers behind each hole to close the flapper tighter, but still leaks at a idle. So that's a maybe, but I don't know how to fix it. Even at idle if I disconnect the wastegate rod and hold the flapper shut as tight as I can (pushing on it with a pry bar) it still leaks.

Exhaust mani isn't cracked, nor is the turbo.

Sorry for the long post,. but I'm stumped. I need help here bad, it has never taken me this long to figure something out like this before. I guess boost leaks could still be a possibility, but I've done the test 5 times now and haven't heard anything, I do it with soapy waster too and I see no bubbles, thanks for your help guys!

 

[silver bullit]

Wastegate checked for failure, and how is the side to side and in and out shaft play?

Summarize what your problem is.

 

[afireinside5976]

Pretty much my problem is I can't run more than 15 psi with my boost controller cranked all the way down, or even just running open waste gate (did that to check boost controller). My wastegate is fully shut at an idle (the only time I can really make sure its shut), but the rod is bent, it was like that when I got it. But that would just keep the waste gate shut at all times right and should make me build more boost instead of less..

Oh and very little shaft play, nothing to be worried about

 

[silver bullit]

You should not be trying to go over 15 psi, you dont have the mods for it (or your not telling us what is done to it), your car is stock.

T-25 cant go more than 15 psi before it shits it guts out and your maxing the fuel pump and probably the injectors to.

You probably have it hooked wrong hoe is the mbc hooked up?

 

[90 tsi awd]

have u tried a different wastegate or do u have a boost restrictor

 

[50trimmed1g]

It might be a failing turbo. That is how mine started to perform when it was starting to die on me.

 

[afireinside5976]

Well today I fixed the 4 stripped manifold studs, the ones from the exhaust mani to head. No differance. Whats a good way to check waste gate for failure? Never had any problems with that so it would be a learning experience.

Boost controller is hooked up right. The bottom nipple of the controller goes to the j pipe nipple and the side nipple on the controller goes to the wastegate. Even with it unhooked I only get 15 psi. I'm not trying to run more than 15 psi, problem is I'm scared I may be over running my turbo, I have to have the boost controller cranked all the way down to get 15 psi, before to get 15 psi I only had to turn the boost controller like half way down.

No I havent tried a differant waste gate and if you mean the boost restrictor solenoid, its removed.

 

[Maxboost1010]

I know you said the most you are putting out is 15 psi, what is the lowest that you can produce (checked with the J pipe niple connected directly to the wastegate without a MBC in the middle)? I'm only asking because on mine the lowest its putting out is 13-15 psi without the MBC connected.

 

[Jordanbutter]

The way I checked my wastegate *actuator* was as thus. I found a hand held bike tire pump and hooked a gauge to it one pump is 10psi and my wastegate is supposed to open at 9psi. I stuck a hose in the pump and then put the other end on the wastegate nipple and pumped, with almost one pump it opened right at 9psi.

It doesn't sound like a wastegate actuator problem. It sounds like a turbo or wastegate flapper problem. Most likely a crack like mine now has.

 

[casperfast]

wow, you have a rats nest of problems, i sgree, sounds like your turbo is going out, is the intake clogged in any way before the turbo?

 

[afireinside5976]

Maxboost1010-I'll try that tomorrow and let you know, I haven't tried that yet.

Jordanbutter-checked the actuator, wasn't the problem, it opened like it was suppose to. I'm starting to think it is a turbo problem too. Maybe the seal? It's not spitting oil, barely any shaft play, and the fins look good on both intake and exhaust side.

casperfast-what exactly do you mean by clogged? But no not that I know of, nothing is inside of it and it isn't kinked.

 

[Jordanbutter]

I would really consider pulling the o2 housing off and looking for cracks around the wastegate flapper. Pull the actuator arm off too so you can open/close the flapper and make sure nothing is obstructing it.