T25... spools to 15psi at 4000?

[curt2go]

Wel I have posted a few other places about this but here is the problem. I hit full boost on a t25 at about 4000 rpms.. That is bad.. It is very sluggish of the line. I mean very sluggish. Compression on average is 158. Tiny boost leak at the TB shaft but still getting the bubbling in the oil on the turblo inlet boost leak test.

I did recently port the t25 mani and o2 sensor housing....

I even blocked of the pcv and same result(It leaks a tiny bit as wee. The new one I bought leaks even more)

Please help.... This now is starting to get madening. i have been chassing little boost leaks but none of them are the culprit. They are all fixed now except for the tb shaft. The boost leak test will get to 20 psi but then slowly go down to 5 psi and stay. Slowlyt meaning about 20 secs to get from 20psi to 5.

Let me know what you guys think. Thanx

 

[Attack Eagle]

HOws the shaft play? Any "cool 767 jet engine sound"?

Sounds almost like you have so much play the blades are rubbing the housing... that will definately kick your spool up stairs to the 3500-4k range as well as casue it to drop off boost between shifts.

t25s only seem to last about 50k or less on average before they start to go

 

[curt2go]

Very little shaft play. I does not lose boost between shifts it is an automatic. I hope to get the cat in and find that is the majority of my problem. I also got the 1g CAS in today so I have that swap to do as well.. TTY

 

[curt2go]

Well I have come to the conclusion that this sort of thing is normal in an automatic. I have even changed the cat to a high flow one but did not do much. My problem may lie in the auto not being able to get rpm's quick enough in first gear from a dead stop. However when rolling and puch the throttle it boost's in very little rpm's under 1000. So with all that said I do not think there is a problem with my car. Except for getting the bottem end better. I do have the 1g cas but do not know how far I can go with the base timming at 15psi? Does anyone know. Is 8 safe? 10 safe? Thanx

 

[doug]

That is NOT normal spool-up for an A/T. I was getting full boost by 2800-2900 RPMs on my T-25. oldman is wise and helpful; just because you have an A/T shouldn't change his diagnostic procedure for pinpointing spool-up problems. It's starting to sound like a boost leak isn't the problem, though, which was my first guess when I saw this thread. I don't think it's your TB seals either; mine were leaking too and I just got them fixed a couple weeks ago.

 

[TSiWarrior]

I have the same problem, Im willing to bet you have a crack in your wastegate area. I used to only be able to hit 10psi MAX ant any time, I fixed some of the cracks with some metal putty stuff, and I can hit 15 now but it takes a while. I'd suggest fixing that if possible.

 

[ddavisaf]

You either have a boost leak or an issue with your wastegate.

My car hits full spool around 4k with a clipped 18G.
I'm not exactly sure what the exact rpm is since I don't care enough to find out. You should hit or be near full spool before you hit 3k rpm with a T-25.

 

[curt2go]

That 4000rpms i speek of is from a dead stop. I will spool up under 1000 rpms when I am rolling..

It is not the wastegate. I have wired it shut with no differnece. I can make over 20 psi if I turn up the mbc as well...

Any other suggestions if you think there is still a problem?

 

[ddavisaf]

Yes. I was making full spool before 3k in my automatic from a dead stop. Boost leak.

 

[doug]

Agreed. Boost leak, pre-turbo exhaust leak, or bad turbo.

 

[curt2go]

What about if the auto is slipping? It would make it look like it is a higher rpm but only the load of a lower one. Does that make sense? TTY

 

[curt2go]

This may be a long shot but I do not know when they changed the timming belt last. So maybe when they changed it they got the timming setting wrong on the cams. 1 cog off or something. Or the timming belt has jumped 1 cog or something? That might explain my bad bottom end and turbo not spooling very fast? TTY

 

[ddavisaf]

Okay, I'm getting annoyed.

1) Fix the boost leaks.
2) Check for pre-turbo exhaust leaks
3) Make sure the turbo is good.

You said you found boost leaks and never fixed them earlier. Did you ever fix them?
Did you ever check for exhaust leaks?

If you want help then do what we suggest and quit arguing with us.

 

[doug]

What about if the auto is slipping?

If the tranny was slipping, you'd know the tranny was slipping. Is it?

 

[curt2go]

Okay, I'm getting annoyed.

1) Fix the boost leaks.
2) Check for pre-turbo exhaust leaks
3) Make sure the turbo is good.

You said you found boost leaks and never fixed them earlier. Did you ever fix them?
Did you ever check for exhaust leaks?

If you want help then do what we suggest and quit arguing with us.

Wow wow wow. Sorry If I am not doing the right things here but I am trying..
1) The leak that I have is in the throttle body linkage. That would not make the spool up time go down by that much. The system will pressure up to 20 psi then slowly about 20 secs go down to 5 and sit there.
2) No pre turbo exhaust leaks. At least none that I can hear. How can i find ones I can't hear?
3) The turbo looked good when I took it off. Very little shaft play and spins very freely.

Also as I have siad before it is very sluggish of the line. It willnot even spin in gravel. If that helps pin point anything?

I don't think the tranny is slipping but it is surging a little at low rpms in 3rd and OD..

I am more than willing to do as I am told here but some things are harder than others..
TTY

 

[doug]

You mentioned earlier that you have a 1G BOV. Any other mods not listed in your profile? Go ahead and finish updating that completely so we can get a better understanding of your situation.

 

[curt2go]

It was really close already but updated.. TTY

 

[ddavisaf]

I was just getting you to help us help you.
Psychology rocks.

1) The leak that I have is in the throttle body linkage. That would not make the spool up time go down by that much. The system will pressure up to 20 psi then slowly about 20 secs go down to 5 and sit there.

This is bad.
You should hold 20 psi for a minimum of 30 seconds.
I want you to run two different boost leak tests from now on until we get all the leaks fixed.
First one is at the turbo inlet. Second one is at the throttle body elbow.
The reason for this is to help you pinpoint your boost leaks more accurately. By testing at the throttle body elbow you're focusing on the throttle/intake portion of the system. Once you get those fixed you'll focus on the entire system by testing at the turbo inlet. If you're not holding 20 psi for 30 seconds, run both tests (turbo inlet/TB elbow) and spray a massive amount of soapy water.
This is your problem as to the 4krpm spool time.

Post back with what you find.

 

[curt2go]

Will do..

The turbo inlet when I presurize there I get bubling inthe oil pan and crackcase pressure. I will try at the tb elbow. I know I have a shaft seal leak as well. I will let you know how it goes.. TTY

 

[ddavisaf]

Will do..

The turbo inlet when I presurize there I get bubling inthe oil pan and crackcase pressure. I will try at the tb elbow. I know I have a shaft seal leak as well. I will let you know how it goes.. TTY

This is even worse. I would suspect a hole in a piston, or failing piston rings.

 

[doug]

Rings, even if his compression test was good?

 

[ddavisaf]

Yes. Reason being.

Did compression test 158,158,164,150 so that was alright. Any more ideas?

164-150. 14 psi difference between cylinders.
That's the ABSOLUTE max it can be at, leading me to believe that his ring may be failing him on the cylinder with 150psi compression.
I could be wrong though.

 

[doug]

Yeah I thought about that after I posted when I went back and looked at his numbers again. My guess is still on some hard-to-find boost leak, though.

 

[ddavisaf]

Very true, before we jump to any conclusions the boost leaks need to all get fixed. Then we can start on the oil pan bubbles.

 

[curt2go]

The bubles in the oil pan are comming from the oil drain on the turbo. Reason I know that when i put the turbo back on and presurized at the inlet it was pushing oil out the drainpipe cause i had a bad gasket on it.. Does that help???

 

[ddavisaf]

Yeap. That is most likely your problem.
And for those nay-sayers, yes a bad turbo seal can cause crankcase pressure.
Piston rings, pcv, valve seals, and turbo seals = crankcase pressure.