Boost Bleeding Off = Bent Intake Valve?
My opinion, I would move it from the booster line. I like all the stuff to have a dedicated signal.
Manifold vacuum to MAP, fuel regulator, BOV
I like to use a signal line right from the compressor housing into the appropriate port on the boost controller solenoid, then on the the gate.
At this point eliminate the variables. Separate the boost control signal from the rest of the components.
Manifold vacuum to MAP, fuel regulator, BOV
I like to use a signal line right from the compressor housing into the appropriate port on the boost controller solenoid, then on the the gate.
At this point eliminate the variables. Separate the boost control signal from the rest of the components.
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My opinion, I would move it from the booster line. I like all the stuff to have a dedicated signal.
Manifold vacuum to MAP, fuel regulator, BOV
I like to use a signal line right from the compressor housing into the appropriate port on the boost controller solenoid, then on the the gate.
At this point eliminate the variables. Separate the boost control signal from the rest of the components.
Manifold vacuum to MAP, fuel regulator, BOV
I like to use a signal line right from the compressor housing into the appropriate port on the boost controller solenoid, then on the the gate.
At this point eliminate the variables. Separate the boost control signal from the rest of the components.
Also I did get the top of the wastegate off today. I measured the spring wire and it is what its supposed to be. There's a double O-ringed piston in it and then an O-ring between the piston and the bottom boost reference line. That bottom O-ring was torn but I thought about it and if anything it would over boost.
Have you checked the turbo for end play. I am wondering if the thrust bearing/washer was going out if it might cause enough friction to prevent the turbo from maintaining boost. I would expect if the thrust were going out that the turbo would start leaking and wouldn't spool worth a crap either. When you did your boost leak test, did you cap the system off before the intake? I am just wondering if the intake could be loose. Also, wondering if the MAP sensor might possibly be defective or leaking. Do you have a boost gauge and are you seeing comparable boost levels on it?
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Have you checked the turbo for end play. I am wondering if the thrust bearing/washer was going out if it might cause enough friction to prevent the turbo from maintaining boost. I would expect if the thrust were going out that the turbo would start leaking and wouldn't spool worth a crap either. When you did your boost leak test, did you cap the system off before the intake? I am just wondering if the intake could be loose. Also, wondering if the MAP sensor might possibly be defective or leaking. Do you have a boost gauge and are you seeing comparable boost levels on it?
Yeah, its still pretty tight. The MAP is a brand new fast and actually reads a pound or 2 higher than my digital boost guage on the a-pillar.
When I did a boost leak test I did it both ways, capped and hooked up to the manifold. I actually found a leak on cylinder #8's injecter o-ring, fixed it and still have this problem. To my knowledge the MAP is good it records a boost drop just the same as the live digital a-pillar guage does.
How big of a boost leak would cause a problem like this anyway?
Just to give you a reference, my bypass valve was stuck open about .125" and I was losing 3-4psi boost. The valve is roughly 1" in diameter. The difference is that I am running a centrifugal with no wastegate. If you were leaking on the intake side, I would expect your turbo to simply spin faster to compensate. I don't have that option. Any exhaust leaks will cause your boost loss as well. Are you sure your wastegate is sealing completely? I haven't read back in this thread, but have you disconnected the vacuum line to the wastegate to see if your boost problem still exists? Removed the wastegate to verify a good seal? Inspected all of the pre-turbo exhaust connections to verify a good seal?
Last edited by BLOWNBLUEZ06; Jul 8, 2009 at 12:21 PM.
After reading the entire thread over, I am betting that something (possibly the torn O-ring) is not allowing your wastegate to close completely and bleeding off your exhaust enough to cause your boost loss.
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I hope you are correct, I took it to a local rubber & gasket dealer & they didnt have it. They said it was a silicone o-ring and they ordered it form me. I'll post the results when I get it back together and try it out. Thanks for the info,
While you're waiting on the new O-ring, I would recommend you remove the wastegate and inspect it for smooth operation when manually actuating it. Also make sure it is free of all debris inside.
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From: Alexandria La.
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I can tell you that JGS had a problem with a batch of there valves for there wastegates. They were not sealing like they were supposed to and people were having your exact problem. In order for you find this out on your wastegate you will have to take the wastegate apart and do a valve lap test on it to see if it is sealing all the way around. If this is the problem I believe JGS will replace it for free. A friend of mine had this problem, and this is how I know about it.
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From: Alexandria La.
I can tell you that JGS had a problem with a batch of there valves for there wastegates. They were not sealing like they were supposed to and people were having your exact problem. In order for you find this out on your wastegate you will have to take the wastegate apart and do a valve lap test on it to see if it is sealing all the way around. If this is the problem I believe JGS will replace it for free. A friend of mine had this problem, and this is how I know about it.
How do I do a valve lap test, what specificly am I looking for? I am so glad you you told me this. What your looking for is where the valve sits on the seat. To test it, I think there is some sort of paint, (or talk to a engine shop) you can put on the seat and then put the valve back in and rotate the valve to create a wear mark on the seat to show how the valve sits on the seal. If there is a spot on the seat that dosn't remove the paint, then it is not sealing in that spot and is leaking boost.
Heck you can use a magic marker and paint the valve and seat with it and then use some rubbing compound and dab it on the valve seat. Then get a lapping stick (the stick with the suction cup or something comparable) and spin the valve back and forth a few times. Where there is marker still on the valve or seat, you are not sealing.
Heck you can use a magic marker and paint the valve and seat with it and then use some rubbing compound and dab it on the valve seat. Then get a lapping stick (the stick with the suction cup or something comparable) and spin the valve back and forth a few times. Where there is marker still on the valve or seat, you are not sealing.
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What your looking for is where the valve sits on the seat. To test it, I think there is some sort of paint, (or talk to a engine shop) you can put on the seat and then put the valve back in and rotate the valve to create a wear mark on the seat to show how the valve sits on the seal. If there is a spot on the seat that dosn't remove the paint, then it is not sealing in that spot and is leaking boost.
Heck you can use a magic marker and paint the valve and seat with it and then use some rubbing compound and dab it on the valve seat. Then get a lapping stick (the stick with the suction cup or something comparable) and spin the valve back and forth a few times. Where there is marker still on the valve or seat, you are not sealing.
By testing without the WG, you can either confirm it is the problem (or the control of it) or confirm it is not the problem and look elsewhere.
Jim
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No, I mean completely remove the wastegate and cap the ends of the pipes that connect to it. A couple simple discs of metal of the right thickness should fit those v-clamps nicely. Then you can do some quick tests to see if boost will go up and stay up. And you can still brake boost with a manual, just use the brake to artificially load the car while moving.
By testing without the WG, you can either confirm it is the problem (or the control of it) or confirm it is not the problem and look elsewhere.
Jim
By testing without the WG, you can either confirm it is the problem (or the control of it) or confirm it is not the problem and look elsewhere.
Jim
Also, I spoke with JGS earlier today. They said that if the valve in the gate wasnt seating right then it would take a while to spool and its not. They also said I may just have too much wastegate for my setup but I dont see how that would make the boost bleed.
Oh I see now, thanks for clarifying that for me.
Also, I spoke with JGS earlier today. They said that if the valve in the gate wasnt seating right then it would take a while to spool and its not. They also said I may just have too much wastegate for my setup but I dont see how that would make the boost bleed.
Also, I spoke with JGS earlier today. They said that if the valve in the gate wasnt seating right then it would take a while to spool and its not. They also said I may just have too much wastegate for my setup but I dont see how that would make the boost bleed.
As for the spooling, that's all relative to engine size, turbo size, system design quality, exhaust back pressure and turbine size. Who's to say it wouldn't spool even more quickly with a fully closed wastegate? It is possible that you have never felt this thing truly spool properly and therefore have no frame of reference.
I am hoping we're right and when you get this resolved and feel that turbo spool better, you find your denture cream no longer works.
