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Turbo spooling trouble...

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B-lackGSX99

15+ Year Contributor
112
2
Nov 9, 2006
Edmonton, Alberta_Canada
Went on a long drive yesterday, a total of 650 miles travelled in about 10 hours straight...drove at speeds of about 90mph for a lot of the stretches. Anyways, when I got back, I let the car idle for a couple minutes (as the last half hour of the drive was much slower and didn't involve spooling the turbo much, if at all) and then it sat indoors at room temperature all night. The following day, I took it out for a quick drive and I noticed that it doesn't want to spool the same as before. It is going into vacuum just fine, so I don't believe I am having any pressure problems in that area. But, when I get it to the point that it used to begin spooling at, it spools much more slowly and makes a very mild "chhhhhhhh" sound that it didn't make before. It does spool though, and I can still hear the blow off valve opening as I let off of the gas. Could my turbine have coked from a lack of proper cooling?? Thank you in advance for the help.
 
It is going into vacuum just fine, so I don't believe I am having any pressure problems in that area. But, when I get it to the point that it used to begin spooling at, it spools much more slowly and makes a very mild "chhhhhhhh" sound that it didn't make before. It does spool though, and I can still hear the blow off valve opening as I let off of the gas. Could by turbine have coked from a lack of proper cooling?? Thank you in advance for the help.
Really there's no excuse for a leak test when you've suddenly can't boost. Coking is possible. Have you logged anything strange?
 
Thank you all for your help, means a lot to me. I will take the car in and have it boost leak tested asap, and also have them check for shaftplay in the turbo. Will report back following this visit to the shop.

For the time being though, is there anyone that has experienced warping/coking thier turbo and can describe to me what it sounds like?? To be more descriptive of what mine sounds like...i'd say it sounds like a mid-pitched softly played kazoo all the way up till I hit about 10lbs, then it seems to clear up slightly. I haven't really been willing to push the car hard since this began, so it's hard to say what happens at higher psi, or when the wastegate pops. Again, thanks for the help.
 
My mechanic, " Say-wha leak test?"

How to build an Intercooler Pipe Pressure Leak Tester

Do it yourself.

so it's hard to say what happens at higher psi, or when the wastegate pops
A popping wastegate should make all kinds of interesting noisesLOL .

I've never had a turbo "coke up" on me. But I've had a "flapping" silicone couple make that same "gazoo" noise when not tightened properly. Vibrating on the intercooler piping. Turned into a mild "chhhh" sound you've previously noted once reaching a certain boost level... This was a boost leak.
 
I agree.

There should be some sort of certification for owning a DSM, and boost leak test would be #1 by far.

It really isn't that hard, and I would have a hard time trusting a mechanic in a noisy shop to hear all the little leaks.

Also, checking for shaft play is extremely easy. Just remove the intake from the vehicle after you have allowed it to cool down. Then reach your fingers in there and try to wiggle the nut on the compressor wheel. You should try wiggling it side-to-side and in-and-out.
 
The same exact problem happened on my friends 1g. It could not boost more than 1 to 2 psi at 100% throttle and made a weird pressure release sound when we let off the throttle. I took a look at it(w/o a pressure test) and found a vaccum line had blown off a tee that connected to the BOV. I put it back on and zip tied it and now it is as good as new. Definitely do a boost leak test and check your BOV, could be an easy fix. Good luck
 
I am definitely able to spool right up till my wastegate opens up at ~15psi. Tried to remove my intake pipe today, but couldn't...I have a dejon piece there that just wouldn't not budge enough after i'd loosened the hose clamps, so I couldn't check for shaft play as planned. I did inspect all the hoses and couldn't find anything noticably out of place...I by no means profess to be a solid mechanic at all. I would like to attempt this homemade boost leak tester, but am assuming that i'd have to figure out how to dislodge that Dejon intake pipe. I'm going to see if I can figure out how to attach a picture of what i'm talking about...maybe i'm just being daft! The bit i'm trying to remove is the one in the picture, which has the cone air filter on one end, and the turbo attached the other end...please correct me if i'm going about this the wrong way. If I can figure out how to open this part up, check for shaftplay and attach boost leak tester (i'm assuming you plug it on at the same place as the intake), i'd feel a million times more resolved. Thanks for all the help. :thumb:
 

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Start off leak testing from the throttle body elbow. Leave the elbow on, just take off that rubber piece connecting it to your UICP. After you fix leaks there, then move to the turbo. Did you take the clamps completely loose? Loosen them again and also loosen where the BOV connects to the intake pipe. (the one right on the blow off valve, not the one on the intake side, and then disconnect it for the BOV) Unplug your mass air sensor. Then after the clamps are loose, pull away. If it still isn't coming out, I would probably take a screwdriver around where that rubber coupler connects to your turbo and try to pry it off somewhat.
 
Yeah Dream On is right. Although, I just test right from the turbo because I think it is too much of a hassle to start fromt the throttle body elbow and work your way back (too much loosening and tightening and adjusting for my liking). What you need to do is take off that filter, take off the tube that goes from your BOV to your intake, and take off the WHOLE intake pipe (take the entire thing out of the car). To get the intake out, you need to push the MAS (the black box thing right in between you filter and intake pipe) toward the passanger side of the fender and get the MAS side of the intake off first and THEN the turbo side of the intake.
 
The silicone coupler at the turbo is just sticky. Afer so many heat cycles it slightly adheres itself to the turbo inlet. Take the coupling clamps completely loose so that PLENTY of daylight are between the coupler surface and clamp. Then, grab her and twist, hard.
 
When I perform a boost leak test, I loosen the hose clamp at the turbo inlet, disconnect the airflow sensor electrical connector, loosen the clamp at the the end of the BOV dump tube, and then remove the air filter, airflow sensor, and intake pipe as one piece. Then, I have plenty of room to hook-up the boost leak tester to the turbo inlet.
 
Sounds great! I'll give it a shot tonight as it all seems way more clear to me now...except for the unplugging of the mass air sensor, but i'm sure that will clarify itself once I get in there! Much appreciated!!
 
It is really not necessary to unplug the MAS sensor (the electrical connection ((towards the top)) that plugs into the MAS), atleast not for me. It is REALLY easy, and in no way should someone "take it in" to get a boost leak test done because really it is THAT easy
 
Okay, got the intake off as instructed by you guys, but there was one thin soft hose underneath the BOV connecting sleeve that was still connected, couldn't get that off. Either way, I was able to shift it enough to the side that I could reach on a check the turbo for shaftplay. I could not make it move in/out or side/side at all, and the blades spun 100% freely with no indication of being warped/coked. Also, there was no oil whatsoever in any of the intercooler piping neighbouring the turbo. When I check the oil dipstick, it reads exactly between the two notches, so I know there has been no out of the ordinary consumption/loss of oil.

I am now fairly certain it is a boost leak. Since I now know how to get the intake off, I will put together a boost leak tester asap (should be able to gather the parts and compressor within a few days), but am wondering if I am causing any further damage to the car running it the way it is. As a reminder, the car is able to spool up fully, so it is not a leak of excessive nature quite yet. I am running it very softly for the time being, attempting to keep the boost gauge in vacuum as much as possible. Please let me know if this is a bad idea, and what the possible negative outcomes (if any), there are. Your responses are, as always, greatly appreciated.
 
Driving around with a boost leak will not necessarily "hurt" your car. But, it will hurt your gas mileage and overall throttle response/power. So, if you HAVE to drive it around, I would say go for it. You won't damage anything if that is what your asking.

Explain a little more about this "connecting sleeve." I have never heard of this. Although, it could be a spacer of some sort because the outlet of the BOV is too small for the inlet of the recirculation tube and to have a tight seal the guy before you placed a spacer in there (thats what I had to do on my HKS SSQV).

You should be able to pull everything off and out of the way. Keep at it!
 
Well actually depending on the size of the boost leak it can actually do some damage, that is if your doing WOT pulls. Under normal driving you should be fine but if your trying to make full boost & your leaking that pressurized air out, the turbo is working much harder to try & produce the required boost. While this isn't so bad with larger turbo's, the T25 is tiny to start with & can barely keep up with even a small amount of boost increase. Now add ontop of that your now making the turbo work even harder. If this is done regularly you will defently shorten the turbos life, not to mention you may also be causing additional engine knock as the inlet charge is now going to be much hotter.

On a side note, I too would also say this sounds like a boost leak issue.
 
I will be sure not to push the car hard, and definitely not to WOT.

The connecting sleeve I was talking about isn't inside the BOV recirc. tube, it is directly below it (a couple inches) on the intake pipe. It is a small diameter (1.5 inches?) soft rubber hose that ran back into the engine bay towards the passenger seat somewhere. I was also wondering, I have an identical soft rubber hose that runs off of the middle of the left edge of the valve cover (you can see it in the picture above)...this hose goes for a couple feet and then just sits there not connected to anything on the other end. What does this hose do, or dump off??

Once I have tested for boost leaks, and hopefully identified where it is coming from, I will report back the results.
 
I will be sure not to push the car hard, and definitely not to WOT.

The connecting sleeve I was talking about isn't inside the BOV recirc. tube, it is directly below it (a couple inches) on the intake pipe. It is a small diameter (1.5 inches?) soft rubber hose that ran back into the engine bay towards the passenger seat somewhere. I was also wondering, I have an identical soft rubber hose that runs off of the middle of the left edge of the valve cover (you can see it in the picture above)...this hose goes for a couple feet and then just sits there not connected to anything on the other end. What does this hose do, or dump off??

Once I have tested for boost leaks, and hopefully identified where it is coming from, I will report back the results.

From the factory there are 3 additional lines connected to the intake pipe, not including the BOV recirculate. One is for the BCS, which is usually disconnected when you hook up an aftermarket boost controller. Next there is a hose for the emissions system, think it attaches to the charcoal canaster & is probably the line you were refering to above. Lastly that line your talking about that comes from the valve cover should also be attached to the intake pipe. If your having issues taking any of these lines off, try twisting & pulling & if that doesn't work use a slotted screwdriver to break the seal while pulling.
 
Okay, before I attempt this boost leak test (i've been trying to read as much about it as possible), I have a few questions. Once I have the tester hooked up the turbo inlet, I am reading that there are some hoses that I need to plug off (PCV?). Can anyone describe to me which hose this would be?? I have an MBC, so from what I understand i'm supposed to block it off somewhere along the hose prior to the intake?? Is this something I want to do right off the bat, or do I want to pressurize, listen, and then block off and again pressurize and then listen for a difference?? Otherwise, i'm just gonna set the compressor to 20psi, spray every IC pipe connection down with soapy water, and hope for the best...!!
 
PCV is on the back side on the valve cover, towards the passender side. You'll see a vacuum hose coming off it going to the intake mani, thought I'm not sure why you want to pull that hose unless your having leak issues & trying to figure out the source. You don't have to block off the MBC but they do have a bleeder hole so you will get a hissin noice & pressure loss from there. If you go over everthing very carefully with soapy water you can probably get away with keeping the MBC connected but its probably easier just to cap it off. Just unhook the inlet side of the MBC & plug that hose. You don't have to worry about the MBC itself & the hose that goes to the wastegate, this will no longer be a leak source.
 
The engine vent hose popping off of the intake will cause the problems you are describing. It will let a large amount of un-metered air into the system and cause you to run pig rich, as it connects to the intake after the mas.
 
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