Valves, Rings, VS?

[1fast97gsx]

I aquired an ams bottom end a while back from another nabr member since my old bottom end commited suicide due to a bad oil pump. I have a 1g head on it with new valve seals, 272s and crower springs and retainers. Bottom end is a 6 bolt with ross / eagle.

Car runs good, blows a touch of smoke at wot, but other than that nothing. Usually the smoke is visable in my rearview just barely, and only the first time I go wot, after that if it's still smoking at all it's so minor that I can't even see it in my mirror. It burns about 1/2 quart to 1 quart max in 3000 miles.

The problem comes in when I'm trying to raise my boost. My external wastegate has a 1 bar spring so 15 psi is not a problem. On my hks evc4 I go to enter 1.35 bar ( roughly 20 psi ) and the car boosts maybe 16 and creeps up to 18. I figure boost leak.

When I go to pressurize the system I get hissing from under the valve cover and with the oil cap off I can pinpoint the source of my leak to be inside the crankcase with no other leaks anywhere. I pressurized from the turbo inlet, but after doing the test once I then pressurized from the tb elbow.

This leaves me with bad rings, valves, valve seals or I suppose a headgasket or even a turbo. My compression tested 165-170 across and only went up a few psi when doing a wet test. I figure this eliminates rings. I'm not pushing oil or coolant and they aren't mixing. Once again compression is good ... head gasket eliminated? I get no smoke at take off or idle .. valve seals eliminated? Turbo has almost no shaft play and is pretty much brand new, and even after doing a boost leak test at the tb with the turbo bypassed I still get hissing in the crankcase ... turbo eliminated? Compression is good, car runs fine, valves eliminated? PCV is replaced with a straight fitting ran to a seperate catch can and the other breather port goes to a catch can as well. I have no egr as I am running a smim. This is throwing me in a loop, everything that could casue this problem seems to check out fine so I'm confused on what to do. ANY ideas or tests I could run would be greatly appreciated.

 

[JamiesTSI]

I would think you would hear air in the crankcase as air by-passes the ring ends. As far as oil consumption gose I wonder what the ring end gaps are? Could be on the large size and getting a little oil blow by.

Sounds odd as to why the turbo won't build boost. Is there some type of duty cycle that needs to be set on the EVC? Did you try uppin the boost anymore, above 20 psi?

 

[1993TalonTsiAWD]

First off before we go anywhere are you doing the pressure test right? What does it get to and what can it hold for 30sec or so? Also Are you spraying soapy water around the area to try and find the leak? Did you crank the enigne over a bit and try it again, because you can land on a time when the valves are a bit open and you get false readings.

Next and only after you have determined there is no leaks. disconect your waste gate vac line. (WITH CAUTION!!!!)Go for a ride and see if it climbs,but not too much because im sure you know the damage it can do. If it does rise above that level then the falt it more than likly the boost control setup. Make sure thats hooked up properly. If you not sure how it should be and have tried all you can do yourself go to AMS and have them look at it.

I really doubt it's the engine though I feel it's somthing to do with you boost control setup.

How does the engine run other wise? Any misfires or backfires? Whats vac at idle? How many miles is on the used engine and other preformence parts?

Anwser these and we WILL help you out?

Derek

 

[1fast97gsx]

Thanks for the responses guys. Other than the not being able to raise boost over 17-18 there are no problems. No backfires, sputters or anything else. Idle is perfectly smooth. Vac at idle is around 340 - 350 mm/hg at 900 rpm with hks 272s.

Back to the boost leak test ... is it normal to hear some hissing in the crankcase from air bypassing the rings through the gaps? I can pressurize the system to around 30 psi but it will drop decently fast until it hits around 17-18 and from that point on it takes 3-4 seconds or so to drop a psi. Assuming SOME hissing in the crankcase is normal I suppose a bad turbo could still be an option. If I disconnect the wastegate lines I get infinite boost, so I know the turbo is capable of making the boost, just for some reason won't do it. Yes I tried rotating the crank a bit and trying to test again, same results each time.

As far as the boost controller hook ups ... I followed HKS' instructions EXACTLY for an external wastegate type setup and on my old motor hooking it up the same way I was able to run 22-23 psi all day so it's not my boost controller setup.

As far as my mods, I just updated my profile last night so that's my current mods. The engine has a total of 10k on it at this point and is just over a year old.

 

[1fast97gsx]

Did you try uppin the boost anymore, above 20 psi?

Yes, I will get an extra 1/2 a psi or so and it will slowly TRY to creep up but doesn't creep up more than another 1/2 a psi or so. This is with the controller set for 26 psi. I'm lucky to hit 19 by the end of 3rd gear.

 

[1993TalonTsiAWD]

Ok if you say the turbo can build boost over 22 or so with waste gate detched then that means your engine is healthy enough. And if you say the boost control system is hooked up right than I beleave you. If that checks out and the turbo seems to be in good condition then I would check the only thing remaining the external waste gate it's self or the source from where it's getting it's signal. Where is it getting it's source from the bov,or the intercooler piping, or off the turbo it's self? Next if you look around on the manifold where the waste gate ataches look for black traces, you know like where a exhaust manifold is leaking. Also no respect to SBR,but I see thats the kind you have and I do remember a post a while ago about some of there manifolds cracking. Now I;m not saying there bad product it was just a material defect and SBR was good about replacing them. I think you should looks for cracks on the manifold to be 100% sure, because with a bad waste gate or cracked manifold that would cause the turbo to work harder and may be spinning 35-45psi and only 22-23psi is coming out, because thats all it can do, sorta like a boost leak, but on the hot side.

Anyway see what you can find out and get back to us. Also on the boost leak test. Some people are very strick about hissing are in the crank case, but to be honest I have some on my engine and it's a ross/eagle 8.5:1 with around 8000 on it so I wouldn't worry. There may still be a leak though I would have to se the test in person to give my full view.

Derek

PS mods were did the spell check feature go...I miss it

 

[1fast97gsx]

Thanks again for your help. I have also considered the wastegate as a problem, however last year the wastegate worked fine on my old motor so I find it hard to believe it just went bad from sitting for a few months. I'm sourcing a pressure source off of the turbo of of the compressor housing and another off of the p port on the throttle body. I'm assuming the way the controller works is once both source pressures are equal ( which should be within milliseconds imo ) it opens the wastegate. I suppose I could try and cap the p port and take it off of an extra nipple on my smim that is currently capped, but I thought the p port was was also a pressure port. If you are questioning anything about boost controller hook up you can see the correct way to do it here: http://www.hksusa.com/faq/?ID=1647 ( mine is the evc4 )

As far as the exhaust manifold goes for cracking I see none. The only exhaust leak is a VERY minor leak on my O2 housing to downpipe gasket however that is after the turbo and wastegate so that shouldn't really cause any boost problems.

 

[JamiesTSI]

Do you know anybody local that would let you borrow a manual boost controler?
i.e. if your able to build boost with the MBC then something is wrong in your EVC set-up.

I would just take the source off the compresser housing only.

 

[1fast97gsx]

Do you know anybody local that would let you borrow a manual boost controler?
i.e. if your able to build boost with the MBC then something is wrong in your EVC set-up.

I would just take the source off the compresser housing only.

When you say source off the compressor housing only how do you mean to do that? The boost controller has a nipple for a source and it has a t fitting that goes into 1 of the wastegate lines that requires another pressure source. I'm assuming this is to keep the wastegate shut?

The hissing in the crankcase was my main concern, is it safe to assuming some hissing is normal? The more I pressurize it the worse it gets, at around 15 - 17 psi there is barely any crankcase noise, at 30 psi there is lots more. Normal?

If it comes down to it I have a mbc to try, but the ebc worked fine with my old motor and all that was changed was the bottom end. Everything else remained the same, so I think if it was bad it wouldn't have worked properly before either. I may have some time tomorrow to play with it and find out more. Thanks.

 

[JamiesTSI]

If you are running a 2 port external, the top port is to hold the wastegate shut. While the side port will open the wastegate.

On my particular set-up, I come right off the compressor into a tee. One hose goes to the side port while the other goes to the solinoid. The other side of the solinoid goes to the top of the wastegate. Being that the solinoid is N.O. it will put pressure on the top of the wastegate, when the solinoid closes it puts all the pressure on the side of the wastegate to open it.

On the MBC idea, I just thought for the short amount of time it would take to install it would help to start eliminating things.

Yes, some air will sneak past the ring end gaps.

 

[1fast97gsx]

I ran a pressure source to my ebc from my smim and capped off the throttle body port and it seemed to fix my boost problem. I had the controller set at 1.30 and it went straight to just under 20 psi. I still got some blueish smoke during boost though so I'm assuming the turbo is shotsky once again. Thanks for your help I will post again when I solved the rest of the problems.

 

[1fast97gsx]

Well it seems that my problem is not fixed. That day it worked fine ( I only floored it twice and it hit 20 ) was over a week ago. Once *I thought* the problem was fixed I pulled it in the garage and left it sitting until today. I took it for a drive today and it's doing the same shit again. I'd REALLY appreciate some more advice/input. Does anyone rent out leakdown testers? Any other possibilities that I may have overlooked? I find it hard to believe rings could cause such a minor boost limitation problem.