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

 

[curt2go]

Maybe the wastegate. I am going to wire it shut and take it for a little spin. keeping in mind I would have not control over boost. Just want to see if it spools up quiker... Maybe it is not seating right.. Hopefully not a bad idea.. TTY

 

[curt2go]

Nope . Not the problem... NOw i am stumped.. Sorry for rambling.. TTY

 

[keymaster]

Ya know, I'm having the same problem with my 14b. Never got any responses here either. The only thing I can think of is turbo seals. Does your turbo have any shaft play? Blowing any smoke?

 

[curt2go]

It would only blow smoke as far as I know after I did a pressure test. i think it puts oil in the exhaust that just urns off. But not sure. I am going to check my timming again tonight cause hopefully I am getting my 1g cas today. Could be knock sensor as well retadring the timming all the time. I really need to figure it out though. It is killing me.. TTY

 

[oldman]

1. How much pis was the system holding in your last boost leak test?

2. Were you having spool up problem prior to the turbo porting?

 

[xcelr8n]

Pre turbo exhaust leaks will cause similar issues.

 

[curt2go]

Oldman I know that it was spooling about the same time prior to the port job. I thought it was normal. this is my first turbo car. Came from a long line of juiced up small block chevies. As for the leak test it would go up until the bov start leaking then go down to about 5 psi . It would take about 20-30 secs to leak from 20 to 5psi. Still a little boggled by this whole issue.

I will add when I looked at my timming at idle I could not see the timming mark anywhere near where it should be. Tonight if I don;t get the CASD I will rev thre motor to see if the mark comes into veiw. Maybe it is just that simple. TTY

 

[oldman]

As for the leak test it would go up until the bov start leaking then go down to about 5 psi . It would take about 20-30 secs to leak from 20 to 5psi.

Do you still have the stock BOV? If so , are you saying that you were only able build 10-12psi when pressure testing? This is no where near the desired test results and can very well be the cause. I think last times we spoke, you were suppose to run some tests but you never came back to that thread to update. I see that you had posted multiple threads about boost leak tests which I was not involve in. If you would like, post me the link to one of them which you think was the most successful so I can take a look and see if other members involved had missed anything.

 

[curt2go]

I have the 1g bov... I was updateing that thread but no one was listening.. IT may not have been in the right spot...

I will update you now.. Did the leak test on the turbo inlet ... bubles in the oil pan. Went to the licp had a couple little ones at the TB. One in the shaft so I did not fix taht one yet. The PCV valve was leaking a bit but did a run with it blocked off and no change. Really no leaks anywhere eles.. Did compression test 158,158,164,150 so that was alright. Any more ideas?

 

[oldman]

The PCV valve was leaking a bit but did a run with it blocked off and no change.

It's ok to pressure test with the pcv blocked off but do not drive it, well a couple of test pulls are ok but nothing more.

I will update you now.. Did the leak test on the turbo inlet ... bubles in the oil pan. Went to the licp had a couple little ones at the TB. One in the shaft so I did not fix taht one yet. Really no leaks anywhere eles.. Did compression test 158,158,164,150 so that was alright. Any more ideas?

The key question is, was the turbo inlet your final leak test? If so, how much psi did it go up to?

 

[curt2go]

Inlet test was first.. It would go up to 20psi then the bov would bleed a little then slowly leak down. 20-30 secs to leak from 20-5ish..
Dam CAS did not come today. There is no way to adjust timing on a 2g mannually is there.. Thanx

 

[curt2go]

i did not to a hard run with the pcv blocked just quik to see how fast the spool up was.. Maybe I have this whole spool up wrong.. When you measure spool rpms is it the rpm's that the engine is at when you hit full spool OR is it the rpms you were at plus the spooling rpm's to get to full spool. For example..


1) Mash the gas from stand still turbo gets to full boost from 0rpms to 2000. We hit full boost at 2000 rpms... this is just an example..

OR

2) Mash the gas when engine was at 2000 and the turbo took 2000 rpms to spool up giving the number of 4000 rpm's to get to full spool? Is this the spool rpms?

This is probably very basic but I am still a newbie..

Thanx

 

[oldman]

When you measure spool rpms is it the rpm's that the engine is at when you hit full spool OR is it the rpms you were at plus the spooling rpm's to get to full spool.

rpm when hitting full spool, mostly refers to a 3rd gear pull unless specified.

Inlet test was first.. It would go up to 20psi then the bov would bleed a little then slowly leak down. 20-30 secs to leak from 20-5ish..

Always end with the turbo inlet test to make sure the TB elbow (one of the most common leaks) coupler isn't leaking after TB elbow test. With that said, if you're able to pressurize the turbo inlet up to 20psi, regardless of the holding time, boost leak isn't the cause but I would still fix that TB shaft seal when possible.

I believe you were suppose to check

1. Exhaust leaks before O2 housing.

2. The wastegate flapper is completely closed.

What were the results?

 

[curt2go]

Wastegate flapper is completely closed. I even tried a run with it wired shut. No change..

So let me get this striaght.. First off I have a auto but second off then turbo spool rpms are measured in the time it takes from where you are at (lets say 2000rpms) till the time to hit full spool (lets say 4000 prms) would that make the spool rpms 2000? or 4000 rpms? I just need to clarify cause I may be thinking totally wrong and may not have a problem with my turbo????? Let me know just in case I have to kick my own butt.. Thanx

 

[oldman]

First off I have a auto but second off then turbo spool rpms are measured in the time it takes from where you are at (lets say 2000rpms) till the time to hit full spool (lets say 4000 prms) would that make the spool rpms 2000? or 4000 rpms? I just need to clarify cause I may be thinking totally wrong and may not have a problem with my turbo????? Let me know just in case I have to kick my own butt.. Thanx

Damn did I miss that some where or did you forget to tell us? I'm not at all familiar with ATs, someone else with an AT will have to chip in.

 

[curt2go]

No I have said it was an auto before. But as for the spool rpm's now this is real data if I am at 3000 in 2dn gear(auto) and punch it the turbo will hit 15 psi by about 4500.. Does that mean my spool rpm is 1500. I think I am a total retard??? Is this correct. I would not say in this case that my spool rpms are 4500???? This must be a total fundimental question but it is not definitevly answered anywhere.. TTY

 

[oldman]

That should mean that the spool up time is 4500rpm but someone with an AT should confirm this as well as chip in on whether 45k is normal for ATs.

 

[curt2go]

So then at normal driving 1/4 throttle at 3000 rpms you shoudl have full boost?

 

[oldman]

So then at normal driving 1/4 throttle at 3000 rpms you shoudl have full boost?

NO, spool time refers to the rpm when you hit full spool. If your boost is set at 15psi, then it's the rpm when you hit 15psi.

 

[ddavisaf]

T-25 Automatic should reach full spool before 3500 rpm.
Mine reached full spool at about 29-3200. Hard to remember exactly. But I had an exhaust leak that was very minor also. Seems one of the turbo to manifold bolts and broken off and the top of the bolt was just sitting on the hole so the person who had it before me didn't look stupid.

Remember though, that with an automatic your car is downshifting into a lower gear, so your "spool rpm" isn't an exact science.

If you're at a stop, and you punch it from a dead stop. What do you reach full spool at?

 

[curt2go]

Ok.. From a dead stop to full spool at about 4000 rpms. But when in like 2nd gear at around 2000 rpms then punch it spool up by 3500 about so it only takes 1500rpms to reach full spool when moving.. Man I wish I could come to conclusion here...

PS The timing is a 5 degrees btc.

 

[curt2go]

"NO, spool time refers to the rpm when you hit full spool. If your boost is set at 15psi, then it's the rpm when you hit 15psi."


Thats what I thought I you punched it from 1/4 throttle when your rpms were at 3000 in 2nd or 3rd gear where would you hit full spool?

Thanx for all the input so far. I just need to figure this out to go on if I am actually having a problem... TTY

 

[polarmoment]

curious, how many miles are on your car? if it's high mileage, maybe the cat is becoming plugged. if the spool was about the same before the porting job, maybe this is the problem. a clogged catalytic converter would definitely affect spool. just a thought...

 

[curt2go]

144kms ... I am getting a hiflo cat this week so I wil be changing it anyways.. I had a thought that maybe that might contribute. I will keep you all informed. TTY