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Vacuum leak? Other possibilities? A/F Learning


caramall2

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I haven't checked voltage or fuel pressure. I can check these.

 

When the a/c is on the maf only goes up to 4 g/s from 3 g/s which isn't in a different cell. Plus, the A/F learning #1b is still around 1%. The maf calibration is still stock.

 

The tune is just the ots cobb stage 2 map. I plan on tuning with opensource in the very near future because I just picked up another lc-1 to log with.

 

Once I figure out the idle fuel trim I plan on fine-tuning the open loop fueling and re-calibrating the maf anyways. Even with the stock intake, it seems that it can always be a little better; it was this way with my impreza.

 

Thank you for the help and suggestions. I may have to bite the bullet and find a shop to do a smoke test.

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yes, so your maf scale is stock, if learning a is still way off, something mechanical is wrong..thus meaning you should do a smoke test. there's no reason to be adjusting your scaling with stock intake/filter/injectors, you'd just be bandaiding a mechanical issue. learning b range is hard to hit consciously, so it will usually bounce from a range to c range while stopping and starting driving
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Update:

 

I did another vacuum/boost test and again there were no leaks. The inlet held 15 psi solid and then blew the tester out of the inlet. I tweaked the ots stage 2 tune because I don't really like it and installed my wideband. I'm getting a netbook this weekend and am going opensource. Here is my latest learning view from last night after idling/driving for 2 hours.

970219381_LearningView_SS_A2WC510N_2012-08-04012402.jpg.9806863b22e54f9c25d0a7f604bc5879.jpg

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Update:

 

I did another vacuum/boost test and again there were no leaks.

 

If you have no leak, why are your idle fuel trims at +4? Something is off. With a stock intake and MAF scaling you should almost always have negative fuel trims.

Obligatory '[URL="http://legacygt.com/forums/showthread.php/2008-gh8-238668.html?t=238668"]build thread[/URL]' Increased capacity to 2.7 liters, still turbo, but no longer need spark plugs.
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I've seen stock wrx's, lgt's with no vac or boost leak confirmed via smoke and compressed air test still have slight positive trims. from what I've gathered, slight improper airbox seal with the filter have caused small positive changes, or tiny maf seal leak
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I will check the airbox and maf again. My understanding is that anything +/-5 is ideal. I am not an expert though and do appreciate the help. Next step is to check for a leak at the exhaust manifold, crossover and uppipe connection. I will also check the o2 sensor.
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Anything 0 to -5 is ideal. The stock MAF scaling is set up to run the motor rich at zero trims and almost always has subtract a little to run at stoich.

 

Having said that, idle trims can bounce around a bit. LV is just a snapshot, you could log the car idling and see what the average trim is.

 

Have you cleaned the MAF sensor?

Obligatory '[URL="http://legacygt.com/forums/showthread.php/2008-gh8-238668.html?t=238668"]build thread[/URL]' Increased capacity to 2.7 liters, still turbo, but no longer need spark plugs.
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  • 3 months later...
So just to clarify guys, My A/F bounces around during driving, from -25%to 25%. is this ok? I just changed my inlet hose also, and ended breaking a nipple on my Vaccum switch ( Solenoid beneath intake manifold). Anyway, replaced it. I know from previous Smoke down test I may still have a slight intercooler leak, but by A/F learning #1 is pretty stable now; within +/- 3%.
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Inlet was torn. The nipple was part of the purge sensor solenoid( Vacuum Switch). It is actually attached to the same bracket that holds the boost controller.

 

Question... Which way does the arrow on your purge valve point? Inlet or fuel tank? My brother and I were opposite. I believe it points to the inlet tube line, but I'm not sure.

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Correction... I've been told by the dealership that Subaru uses similar names for different parts. Unless it's the same part we're talking about, the sensor I'm referring to sits directly beneath the intake manifold, with two nipples pointing towards the front of the car. There's another sensor infront, beneath the alternator, is that the one you're referring to?
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So just to clarify guys, My A/F bounces around during driving, from -25%to 25%. is this ok? I just changed my inlet hose also, and ended breaking a nipple on my Vaccum switch ( Solenoid beneath intake manifold). Anyway, replaced it. I know from previous Smoke down test I may still have a slight intercooler leak, but by A/F learning #1 is pretty stable now; within +/- 3%.

Correction, A/F Learning still all over the place, from -10% to 10% times, ( but usually in the 7% region). Vacuum pressure ranges from -9.6 to -10. Which is better than before. So, I don't really suspect a vacuum leak. Double and triple checked all hoses. Also, I have a K&N Typhoon intake..car is tuned for it. All answers/ suggestions welcomed :spin:

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Here are two pics showing where the hose was disconnected at the purge valve and where the other end of the hose is connected. The third is a piece I found (credits to boostin) highlighting where the purge valve should connect according to the fsm.

Do you know if the lack of the foam around the purge valve 'thingy' affects it's efficacy?

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