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No Boost In 1st?

Charles89

By Charles89,
in Engines & Forced Induction

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Charles89 Grand Master

Charles89

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I don't if it's just me or the car, after a spirit drive, the car doesn't seem to be boosting in 1st gear...

My R34 is pretty much stock, with just fmic, pod, exhaust, it's running stock boost but it creeped up to 9psi.

I'm pretty sure I could hit 9psi in 1st gear before today, but after the drive, it won't boost, it felt like an NA in 1st, then when I changed to 2nd, then it started boosting again?

So then I turned off my car and started it again, then it started boosting in 1st, but it only got to 7psi?

Any help would be awesome!

Thanks

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Charles89 Grand Master

Charles89

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It was just weird, because it wouldn't build boost after spirited drive, then after I turned off the car and on again, it only went to 7psi, but it hit full boost in 2nd, 3rd, 4th. It felt like an NA in 1st gear.......

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Nic_A31 Grand Master

Nic_A31

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Also explains why boost creeps up slowly (slightly open), and only reaching 7 PSI (still slightly open).

I guess it'd work after a gear shift since its been forced fully open then recloses properly or half properly.

Edited by Nic_A31
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Nic_A31 Grand Master

Nic_A31

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You turn the car off and vacumm (intake plenum) is killed, this opens the BOV since the throttle body plate is shut and the spring in the BOV isnt being forced down.

Likely to be a problem with that vacumm line from the intake plenum to the BOV, maybe something in there cloggy it intermittently, or the internals of the BOV...dont know too muhc about them, only seen a basic idea of how they work on WikiPedia and that's always been enough information for me.

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Charles89 Grand Master

Charles89

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Was the engine cold when trying to boost?

You know if there is not heat in the manifold it wont hit boost the air is too dence

Nope, the engine was well and truely warmed up, because after a spirited drive, on my way home, thats when the problem started (non/not much boost at all), then I quickly restarted the car and it started boosting again, but only 7psi in 1st, max boost in other gears, then when I come to a stop, shifted back into 1st, still only 7psi max.

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Charles89 Grand Master

Charles89

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You turn the car off and vacumm (intake plenum) is killed, this opens the BOV since the throttle body plate is shut and the spring in the BOV isnt being forced down.

Likely to be a problem with that vacumm line from the intake plenum to the BOV, maybe something in there cloggy it intermittently, or the internals of the BOV...dont know too muhc about them, only seen a basic idea of how they work on WikiPedia and that's always been enough information for me.

It's weird because it happened outta nowhere :thumbsup:

But after doing some research, there are other cars that had similar problem, even GTR's, and people just suggest to restart the car, as it restarts the ECU, or to upgrade the stock ECU to aftermarket.

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