kcobean

iTrader: (2)

In reviewing the installation instructions (page 19/20), it indicates that there is supposed to be a gasket between the dump tube and the downpipe flange. I guess now a) I know where the 2nd gasket on the wastegate came from (the one that is NOT supposed to be there), and b) I know why I have an exhaust leak between the dump tube and the downpipe.

I'd still love to know how this could cause overboosting though....

kcobean

iTrader: (2)

I'm going to guess that you did this with the turbo itself out of the car? I was hoping to avoid having to yank the turbo out to get to these bolts, but it looks like I might have to, especially since the gasket that was supposed to be installed at the top of the dump tube was installed on the input port of the wastegate instead.

disturbed2483

iTrader: (9)

well unfortunetly yes the turbo has to be out and so does the feed pipe to the turbo, but that is the only way that the down pipe with the dump-tube will go back in from the top.

overZealous1

iTrader: (27)

just curious, i think i read most of the posts till now, but have you tried simply taking the boost controller out of the picture and venting the top of the wastegate to atmoshpere. it would eliminate alot of possibilities if it then only let you build the 5psi of the spring in there.

kcobean

iTrader: (2)

Yep. The boost controller is new in the last couple of weeks. The car has exhibited this behavior ever since the kit was installed back in June. Prior to the top port being connected it was open to atmosphere.

This is all kind of coming up now because Sharif commented after tuning the car that he thought something might be wrong with the wastegate due to the high boost, and I finally got around to getting a new gate from Turbonetics, thinking that this would solve the problem. But apparently not.

overZealous1

iTrader: (27)

try disconnecting the bottom vacuum line and hook a vacuum tester to the top portion of the wastegate. have someone rev the engine to say 3000rpm and start applying vacuum to the top and see what it takes to open it. should hear it when it opens.

MIAPLAYA

iTrader: (3)

Well it appears the weirdness never ends. I still don't see how the wastegate leaking out from the dump tube could do this either but at this point I guess we just need to eliminate every possiblity...

huducks

hey kelly just curious... but whats the highest boost u've seen out of the car so far? not that u would want to find out the hard way.

kcobean

iTrader: (2)

The highest I've seen is 14 PSI, but that was just briefly and I had one eye on the gauge and one on the road. It's amazing how fast the boost builds once you hit around 4K rpm.

huducks

yea tell me about it i know the feeling. i didnt realilize that the ST kit could produce that much boost with the other mods u have on the car now. i was def considering making swap to the turbonetics after seeing urs this weekend.

UnderPressure

iTrader: (4)

The problem w/ the increased boost level lies w/ the problem that not enough exhaust gas is being bypassed around the turbine. (duh).

Check the valve and seat of the w/g. Without the spring in the gate the valve should move freely. Could be a little sticky or not opening fully. That would cause the turbine pressure to rise.
Have you tried replacing the gate assembly completely? Not just the spring. Try swapping it out w/ another know working gate and see what happens.

Ok just read where you got a new gate from T-netics. Try one from a known working car. Chances are slim but it might have been a bad gate as well. Quality isn't exactly #1 w/ their products.

MIAPLAYA

iTrader: (3)

He just replaced it last weekend with another valve and gets the same thing. I'm starting to wonder about the amount of flow from the wastegate. I definitely think he should get that leak fixed and assuming that doesn't do it maybe flip the gate and vent to atmosphere for one run and see how it does.

UnderPressure

iTrader: (4)

Flow from the gate would be the only other possible cause. When the gate is off the tube, check to make sure the port into the exhaust is completely unobstructed. Hole could have been cut to small.

Edited my previous post once I finished reading the reast of the thread. Teach me to jump to conclusions.

Also check the hole size on the return to downpipe tube. The w/g could be fully opening but the hole back into the exhaust might be the size of a coffee stirrer.

MIAPLAYA

iTrader: (3)

Well I must say the the three main people seeing this issue happen to have a similar exhaust set up....EXTREMELY wide open 3 ". I wouldn't say its a quality issue with the wastegate. The wastegates work. Thats been proven time over on this kit. My concern is more then maybe they are flowing SOO much better with these exhausts that the dump tube just can't route enough exhaust gas past the turbine. I know its hard to believe thats it as I don't even believe it myself to the fullest but two of the three have the SAME setup, modified Greddy true duals and the other has the Topspeed Pro-1 which apparentely flows pretty damn well. The one thing to note is that the two that are running the modified Greddy true dual are not only getting 11+ PSI but they are running in the 9s AFR which makes ZERO sense. The injectors are at roughly 100% duty cycle by 10.5 PSI and I know at least in kcobeans case the fuel pressure is exactly like mine.

Sharif@Forged

iTrader: (92)

Hence...its the mystery of all ages....I hope the collective community can solve this one. Several good heads are better than one, I suppose.

UnderPressure

iTrader: (4)

It has to be an issue w/ the wastegate or the related systems. I'm leaning more and more towards the dumptube issue. The downpipe/exhaust can flow sufficent amount of exhaust gas to regulate turbine speed. What seems to be happening is the w/g is trying to bypass the exhaust gases but is unsuccessful. If the problem doesn't lie in the w/g itself it must be post-w/g a simple test would be to remove the w/g dump return and see if the car hold low boost. If not, then it's time to start looking @ w/g placement vs. exhaust back pressure.

Sharif@Forged

iTrader: (92)

If I was looking at this problem in a vaccum, then one could probably point to insufficent wastegate flow...ie...the gate is too small to flow enough exhuast to keep the pressure at the preset level.

But becuase there have been so many successful installs, it's hard to point the finger at the wastegate, especially now that Kelly has swapped it for a brand new one.

prescience

Off the wall but could the gas be flowing in such a way to create some kind of fluid dynamics effect (vortex, eddy or whatever) at the wastegate which is restricting the flow through it - so it opens but can't flow (vent) correctly.

And maybe the freer flowing (faster flowing?) exhaust setup could contribute to the above effect.

Told you it was off the wall and no idea how to verify LOL

UnderPressure

iTrader: (4)

Well that's actually not that far off the wall. I think the problem is going to be much simpler and found as a partial blocked w/g feed or dump tube return.

35ounces

iTrader: (5)

Yeah but he has a leak at that dump tube also which would allow it to flow that way and bypass the turbo to some extent and also as I understand it, other people have run without ANY exhaust and there was no issue.
It would be hard to believe that the dump tube is blocked in some other way too. I mean what would be in there to block it, a cat?

I think there is enough info here and diagnostics that have been suggested that Kelly at least has some things to try. When he has some answers to these things I think he will be able to resolve the issue. Might take a long day at a good shop to try it all.