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Boost Cut?

Black_CSR

By Black_CSR,
in Engines & Forced Induction

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Black_CSR Rising Star

Black_CSR

Posted
Posted

Ok Guys wondering if you can figure this out.. I boosted the car this morning & it hit peaked boost @ 22psi then the car backed off the power like a cooler piping came loose. Checked power FC level, ID% went to 76% n only rev it to 4700rpm. Pulled over all piping tight n vac hose all good.. I only usually peak 61-62% IDC.

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89CAL Grand Master

89CAL

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Posted

Have you got the boost control kit installed or even just the map sensor? This is the only way it will cut the engine because of boost. Only other way is if your airflow voltage is to high that will give a similar effect.

Look at paulr33's power fc FAQ for the answers

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Black_CSR Rising Star

Black_CSR

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Hey mate i have a HKS EVC 5 and Power FC that still uses a Z32AFM. I am thinking that the Spark plugs is not keeping up or something.. n just dumping fuel??? Only thing i can think of is turning the boost gain down a bit. What is the Max volt on the Afm so i can check it if i try again. Knock level was low @ 10.

Edited by Black_CSR
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Hanaldo Grand Master

Hanaldo

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If it was spark plugs it would be a misfire, not a cut. Misfire is usually not as violent as a cut,and very identifiable from the sound. I wouldn't play around with the boost controller either, it's more likely to be something that has changed. What boost do you normally run? I assume the EVC 5 has a limit function like the Greddy Profec B?? What is that set to?

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Black_CSR Rising Star

Black_CSR

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EVC is set to 21psi.. if it goes above 21.5psi it will auto turn it down to by 0.6psi and it will beep. I don't think the EVC will cause the back off in power?? I have changed the turbo intake pipe from 2.75" to 4" n the Bov was slightly open at idle so i tightened it up so it's just closed.

Edited by Black_CSR
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Hanaldo Grand Master

Hanaldo

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No, it shouldn't.

t really does sound like a vacuum leak though, are you sure none of your hoses are loose or split? Is it idling ok? Even if it is, it could be a hose that's split and only leaking at higher vacuum/boost. Could also be AFM as 89CAL said, max voltage should be around 5V. But how much power are you making? I'd be surprised if you were maxing the Z32.

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Black_CSR Rising Star

Black_CSR

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Yeh it ldles fine, Made 370rwhp on a roller dyno last time i checked. 350 on hub dyno with low 10 afr's. Split hose or vacuum leak?? I think i have checked all of them & they are fine. I boosted it again on the way home n turned boost gain down a bit n it peaked 20psi n ran fine. Even the BOV slightly open it was still idling fine.

Edited by Black_CSR
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