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Fuel pressure & ecu / AFM matchup


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#1 Gizahoon

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Posted 18 August 2017 - 7:23 PM

Hey fellas,

Looking for some advice for my 92RS as its hunting for idle after the throttle is let off, it evens out and runs okay after about 5 seconds though.

I know the previous owner played with the fuel pressure regulator, I have a gauge, what should I be setting the pressure to at idle / what's the ideal pressure to run?

Its got yellow injectors, K7 ECU, green afm

I'm wanting to install a wideband and gauge at some point, the exhaust / turbo got really hot when I drove it so I'm assuming its running lean

Any advice much appreciated 😁
04 BP Legacy 3.0R
92 BC Legacy RS

#2 Sammy

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Posted 18 August 2017 - 10:22 PM

yellow injectors and green afm is a big no no. Check your ecu to see if it has an aftermarket chip installed, some people advertise yellow injector tunes but I've yet to see one actually run how it should.

As for the hunting idle, most common is vacuum leaks. Check and replace any brittle lines that show any signs of cracking, make sure they're secured properly with hose clips or heavy duty cable ties (not shitty cheap ones!), common areas are the intake pipe that connects to turbo and the intercooler charge pipe

Other common issues with idle hunting could be coil packs - does it boost alright? IF it's splutters and misses on boost it'll be coil packs

Idle control valve, this is tricky to diagnose, check ecu codes to make sure it's not something else, it should move freely when removed, if not you can clean it out and get it moving nicely again it may work, or replace it with a known good one.
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#3 Gizahoon

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Posted 19 August 2017 - 1:24 AM

The car actually runs really well, no cutting out or strange behavior while under load / on boost.

Currently got the shifter out so can't really test it, turns out the hot smell / smoke was grease over the headers where a CV boot must have split and not cleaned properly after its replacement 😁
04 BP Legacy 3.0R
92 BC Legacy RS

#4 Subiandy

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Posted 20 August 2017 - 7:26 AM

Hunting after boosting could also be BOV leaking, most cases aftermarket BOV tend to do this.
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#5 DCVR

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Posted 21 August 2017 - 4:16 AM

43.5 psi I believe is the correct factory pressure but of course if you have mods this might be adjusted
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