Why does my car make no boost with the wastegate safety-wired closed? - Page 2 - Miata Turbo Forum - Boost cars, acquire cats.

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Old 08-25-2007, 10:42 PM   #21
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Are you sure you don't have it wired open?
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Old 08-25-2007, 10:47 PM   #22
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Totally sure.

I've removed the EGR. Is there a simple way to tell whether it's failed? The valve seems to be closed at rest.
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Old 08-26-2007, 12:24 AM   #23
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What would happen if the turbo wasn't spooling properly? Would you notice a difference in the cars performance due to increased back pressure or lack of ease that the exhaust can escape?

This is the the turbo you got from ebay recently right?
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Old 08-26-2007, 12:37 AM   #24
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Yeah, but the problem started with my old T25 which ran great for 2500 miles.
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Old 08-26-2007, 02:39 AM   #25
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OH, I apologize I didn't understand that.

Maybe its not a charge pipe, maybe one of your vacuum lines came off somewhere.
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Old 08-26-2007, 03:40 AM   #26
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is the boost gauge reading correctly? sometimes the simple things get ya....
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Old 08-26-2007, 03:44 AM   #27
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The car is gutless, and the boost gauge is actually teed off of the MAP sensor hose for the Megasquirt.
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Old 08-26-2007, 06:32 AM   #28
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damn i cant wait to find out wtf is causing this because if its not the charge pipes and its not the turbo, then I dunno what it could be?
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Old 08-26-2007, 09:43 AM   #29
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Makes better sense though. Check couplers for cracks, then check IC. Would be easiest to shoot compressed air into the charge system post turbo and listen for leaks. Check compession and leak down as warranted. Remove BOV.
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Old 08-26-2007, 09:54 AM   #30
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Ben has a point. If your BOV is recirculating, it may be wide open.

+1 on compressing the whole track with air.
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Old 08-26-2007, 11:38 AM   #31
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huge crack in the IC?
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Old 08-26-2007, 02:06 PM   #32
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Like ben and olderguy said, make a boost leak tester with a PVC elbow, cap, and tire valve stem. Remove the filter and clamp that to the turbo intake. Pump 12 psi through the system. You'll hear a psssst where the leak is.

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Old 08-26-2007, 03:02 PM   #33
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I had a probleim with my compressor sealing not to long ago i where i would make 4-5 psi and it would all peeter down to nothing as i got towards redline. Some JB weld fixed my problem right up on reassembly
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Old 08-26-2007, 08:38 PM   #34
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I just put 25+psi through the system, from TB to intercooler endtank, and it blew the fitting out of the TB first. (Nearly took my ******* finger off.) I'm going to figure out a way to test the hotside piping, but I'm also going to have the motor compression checked. I've been through everything but the motor itself.
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Old 08-26-2007, 08:45 PM   #35
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Quote:
Originally Posted by Savington View Post
I'm going to figure out a way to test the hotside piping
Connect the cap to the turbo inlet and test the entire system at once.

FYI for others: you can make a pressure tester from junk at Home Depot for under $15.

If you have a turbo, being able to check your charge pipes for boost leaks with a compressor is essential. It should be part of basic trouble shooting for a turbo car with boost problems yet seems to be a huge mystery in the turbo Miata world. If you can't make boost you test for leaks first and THEN come to the forums. Period.

http://www.mirage-performance.com/Ec...aks/index.html
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Old 08-26-2007, 09:00 PM   #36
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Quote:
Originally Posted by Savington View Post
I just put 25+psi through the system, from TB to intercooler endtank, and it blew the fitting out of the TB first. (Nearly took my ******* finger off.) I'm going to figure out a way to test the hotside piping, but I'm also going to have the motor compression checked. I've been through everything but the motor itself.
If your motor runs than it is not the cause of zero boost.
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Old 08-26-2007, 09:10 PM   #37
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Quote:
Originally Posted by Arkmage View Post
If your motor runs than it is not the cause of zero boost.
yep even with a blown #2 i made good boost
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Old 08-26-2007, 09:35 PM   #38
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I found a pinhole leak in one of my hotside tubes. Nothing that would even come close to venting the amount of air required to cause this problem, though.
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Old 08-26-2007, 10:28 PM   #39
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If the system is sealed from turbo to head and you have no boost = bad wg, bad wg actuator, or bad turbo. If all is sealed then the turbo isn't spinning fast enough to make boost. You can still hear it but something could be causing it not to spin fast enough. Oil cooled only? Maybe it's coked up. Damaged bearing? Could have a bad bearing but feel tight. Process of elimination. If you verified everything from point a to point b and still have a problem then you didn't properly verify something or you have a ghost.

Maybe you floated your valves and bent all the intakes. What did the compression test show?
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Old 08-26-2007, 10:31 PM   #40
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Quote:
Originally Posted by lazzer408 View Post
If the system is sealed from turbo to head and you have no boost = bad wg, bad wg actuator, or bad turbo. If all is sealed then the turbo isn't spinning fast enough to make boost. You can still hear it but something could be causing it not to spin fast enough. Oil cooled only? Maybe it's coked up. Damaged bearing? Could have a bad bearing but feel tight. Process of elimination. If you verified everything from point a to point b and still have a problem then you didn't properly verify something or you have a ghost.

Maybe you floated your valves and bent all the intakes. What did the compression test show?
The problem arose with my 2500-mile journal-bearing T25 and its actuator, then on the new-to-me GT25R w/ the T25 actuator, then with the GT25R and an ATP actuator, then with the GT25R and no actuator at all (wastegate wired closed). It was a sudden failure, so I don't think I bent the valves. The most RPM this motor has ever seen since I've had it has been 7400rpm or so (missed 3rd gear and the motor spun up pretty good, normal limiter is 7100-7200)
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