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

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Old 08-25-2007, 02:26 AM   #1
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Default Why does my car make no boost with the wastegate safety-wired closed?

Just curious.

Came around a corner sideways in 1st last Thursday with my old T25, hit 2nd, and had no boost. I was planning to change the turbo anyway, so I did the swap to a GT2554R, but kept the old wastegate actuator. No boost. Then I switched to a new actuator, no boost. Then I wired the ******* wastegate closed, no boost. What gives? The only thing I can think of is that my EGR has somehow failed (I have a BEGI manifold with the EGR hooked up) and all the exhaust gases are rushing through there. I'm stumped, though; I figured wiring the ****** would give me at least a few PSI on roll-on.
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Old 08-25-2007, 02:43 AM   #2
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You couldnt possibly have all exhaust gasses exiting through the EGR, maybe you have a boost leak in your charge pipes somewhere?
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Old 08-25-2007, 02:45 AM   #3
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Wiring it closed should allow you to boost till you blow. I don't know much about how the EGR would work in this case but it's either going to be the EGR or the WG flap fell off.
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Old 08-25-2007, 02:49 AM   #4
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The WG flap is still on my T25. It's not a boost leak because my car sounds like a ******* Mack truck spooling up. I can't hear the exhaust over my turbo noise normally, and right now there is NO turbo noise. All the basic ideas get shot to hell by the fact that I've changed the turbo and wastegate actuator.

How do I change the god damn EGR? I don't even know how it works. >.<
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Old 08-25-2007, 02:53 AM   #5
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Kinda greek to me as well. Isn't there an EGR valve on the intake manifold that open's and closes relative to vacuum. The valves stick sometimes and I think you can clean them with brake cleaner or something to unstick them. (doing research)

My egr is replaced with a block offplate on the back of the intake.
http://forum.miata.net/vb/showthread...ight=stuck+EGR
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Old 08-25-2007, 03:11 AM   #6
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Could it be that your new turbo isnt spooling at all?

As for EGR, I think it only activates at idle and cruise.
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Old 08-25-2007, 03:13 AM   #7
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I've had this problem on two different turbos. Both spin freely with minimal shaft play. I could see the T25 spinning at idle with the intake tube off.
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Old 08-25-2007, 04:10 AM   #8
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check charge pipes
then recheck
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Old 08-25-2007, 04:20 AM   #9
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Will I really hear no turbo noise at all if I blew a charge pipe off?
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Old 08-25-2007, 04:28 AM   #10
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actually this just happened to me like 2 days ago and the turbo would not audibly spool when the pipe blew off. I suppose with the lack of actual boost increasing the exhaust pressure, it just cant quite get spinning quick enough.
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Old 08-25-2007, 04:44 AM   #11
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yeah you should hear some noise, but it will sound completely different than what you're used to hearing. you'll hear the 'spinning' but none of the 'wooshing', hard to explain
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Old 08-25-2007, 06:01 AM   #12
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id also say check your pipework, if you have a cooler check that you havent got a hole in it also...... but in saying that you would normally hear a pipe come off or a cooler pop, it sounds like something poping & its loud, this happened to me once on my rx7 & trust me you know about it, in fact the pipe that came off did so with so much force that it dented the strut tower that it hit....
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Old 08-25-2007, 06:25 AM   #13
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it does not necessarially mean any loud sound though, pipe can work off slowly.
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Old 08-25-2007, 08:45 AM   #14
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I would still consider the EGR as a possible culprit stuck open, it's either that or a pipe blew off.

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Old 08-25-2007, 09:47 AM   #15
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Cracked manifold? Blown manifold gasket?
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Old 08-25-2007, 10:13 AM   #16
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+1 on manifold seating surface or manifold leak preturbo. Even with my charge pipe damn near off i got 3-5 psi most of the time :gay: Pull the manifold and inspect it thuroughly cracks are a bitch. and gaskets suck when they fail as well.
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Old 08-25-2007, 11:44 AM   #17
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cracked mani/open pcv/blown hg, etc the car would still make SOME boost. even with everything functional and a tied open WG, it should still make a little positive pressure.

best explaination for no boost at all is a problem in the charge pipes.
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Old 08-25-2007, 02:02 PM   #18
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I had the manifold off extracting a stud when I changed turbos. I did not see any blatant cracks; I would think a problem so serious that it wouldn't spool the turbo would come up as a really ******* loud exhaust leak. The car sounds normal, mabye a tiny bit louder. Certainly not exhaust-leak loud.
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Old 08-25-2007, 08:02 PM   #19
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look at everything between the TB and turbo.
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Old 08-25-2007, 09:13 PM   #20
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I just drove the car and pushed it pretty hard. I can get to around 3psi at 5000rpm. There are no charge pipes broken; I pulled on them all pretty hard and none came loose in my hand. The wastegate is still wired closed. It makes boost VERY slowly, which leads me to believe that the pressures in the EM and the IM are constantly trying to equalize.

How hard is it to block off the EGR? Can I block it off and have no issues if it has really failed?

Does a 1.6 have an EGR? I have a salvage 1.6 that used to have a turbo, and I cannot see an EGR tube on it. If I can find the EGR on that motor, I can use its blockoff plate, possibly?
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