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Miata Turbo Shuts Off

Old 03-31-2016, 08:41 PM
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Default Miata Turbo Shuts Off

Hey everyone,

Hopefully I can get some help here. I recently finished installing a T25 on my 1999 1.8. It has an ebay manifold, with custom intercooler piping, and a custom downpipe. I am using a Flyin' Miata Voodoo Box for engine management. I tuned it following the instructions that came with the Voodoo Box.

The car runs great when it isn't in boost, however after hitting boost and letting off the gas, the rpms drop and sometimes the car cuts off and dies, other times, the rpms will drop and go back up and idle very high around 2k. After cutting off, the car will turn back on normally. My boost gauge is telling me I am hitting 6psi.

The only thing I could think it is, is when installing the downpipe, I accidently snapped one of the bolts off, so only four bolts are holding the downpipe on to the turbo. Could a small exhaust leak be the reason this is happening?

Please help!
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Old 03-31-2016, 08:45 PM
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What kind of blow off valve setup are you using?
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Old 03-31-2016, 08:49 PM
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I am using a Bosch recirculating BOV. Thanks for responding!
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Old 03-31-2016, 08:51 PM
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Originally Posted by faviles5566 View Post
I am using a Bosch recirculating BOV. Thanks for responding!
As long as it is recirculating back after the MAF it should be fine. That was my only guess.
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Old 03-31-2016, 09:16 PM
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Here is a picture of the engine bay the BOV is right after the MAF
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Old 03-31-2016, 09:46 PM
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Originally Posted by faviles5566 View Post
Here is a picture of the engine bay the BOV is right after the MAF
LOL. BOV is plumbed wrong.
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Old 03-31-2016, 09:47 PM
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Where is that BOV hose going to?
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Old 03-31-2016, 09:53 PM
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Originally Posted by sixshooter View Post
LOL. BOV is plumbed wrong.
I'm extremely embarrassed. What is wrong with it?

The hose is going to a nipple that was welded on a few inches after the throttle body
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Last edited by faviles5566; 03-31-2016 at 10:22 PM.
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Old 03-31-2016, 09:57 PM
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Does it idle?
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Old 03-31-2016, 10:00 PM
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BOV mounted onto the intake side of the turbo? Poscat to you sir.


Attached Thumbnails Miata Turbo Shuts Off-80-66316081_72b7ae0df38e43a4ad3e137b8ed0f0dd1a954091.jpg  
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Old 03-31-2016, 10:28 PM
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Wtf is going on
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Old 03-31-2016, 10:42 PM
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You were pretty close, man. Here, I drew a sweet picture that should explain.

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Old 03-31-2016, 10:45 PM
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Also what's up with the washers on the exhaust manifold?
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Old 03-31-2016, 10:58 PM
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Your first diagram should work just fine. That's essentially how BEGI routes theirs, except with the BOV fipped. It's common to use that BOV flipped, as boost pressure helps it seal shut.
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Old 03-31-2016, 11:13 PM
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In that case, he'd still have to swap the "direction" of the BOV.
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Old 03-31-2016, 11:15 PM
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Direction of the BOV doesn't matter. It's just a piston that opens and allows air to flow. What he needs to do, is route that pre-throttle.
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Old 04-01-2016, 07:42 AM
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IIRC soviet was using a similar BOV, he had it mounted halfway between the intake and cold side plumbing
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Old 04-01-2016, 07:58 AM
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Where is your idle valve connected?
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Old 04-01-2016, 10:24 AM
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Originally Posted by faviles5566 View Post
I'm extremely embarrassed. What is wrong with it?

The hose is going to a nipple that was welded on a few inches after the throttle body
As long as that longer, ~1" diameter hose is going into the correct end of the BOV, this set up will work just fine. Where the BOV is mounted matters none, except for its sensitivity/response. It would operate better mounted on the charge pipe.
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Old 04-01-2016, 10:32 AM
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Flip this the other way

Put it closer to the charge pipe on the cold side.

I'd swap your T fittings locations also, put them closer to the intake manifold and just side by side so manifold==t=t======emissions thingy
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