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 Post subject: 2002 USDM WRX going lean on boost (vacuum leak??)
PostPosted: Wed Oct 17, 2012 10:28 pm 
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Joined: Wed Oct 17, 2012 10:19 pm
Posts: 2
Greetings!

I have a 2002 USDM WRX that has recently started running lean on boost, and I'm looking for ideas, and tips on how I might track-down the cause via logging. I've done lots of searching, and lots of reading debug-threads for similar issues, but I haven't found a workable solution, so I thought I'd go ahead and post.

The current map started as a commercial tuner (open source) reflash, but has some very minor mods. I've been running said map for 2+ years (and the car was previously fueling just fine, and running strong.) Engine wise, it has:

Stock 2.0 block
Stock 2.0 heads
Stock turbo
TurboXS TUNA Pro wideband O2
APS short-ram intake
Perrin intake hose (from MAF to Turbo)
APS turbo-to-intercooler hoses
Perrin electronic boost controller
Vishnu uppipe
Turbo XS turbo-back
STi pinks
Perrin fuel rails
Aeromotive fuel pump
Greedy boost, fuel pressure, EGT gauges
and lots of samco hoses, and little odds and ends here and there that shouldn't be related

Other than the fuel pump and new stock fuel filter (which I replaced while exploring causes), all of these bits were installed years ago, and it's been fine up until recently.


On a potentially related note, sometime last year the car had an idle problem one morning. I cleaned the IAC, and the problem went away; however, since then, it's had a little stumble just as I blip the throttle coming off idle. If you weren't expecting it, you might stall coming from a stop. Unfortunately, I don't recall whether the lean condition started at the same time. The car also exhibits the occasional-mysterious-white-smoke-puff-from-the-scoop problem if it's been sitting a few days. I've been writing that off as a dying, leaky turbo.


On to the current problem though. I've included a RomRaider log snippet below showing the AFR problem on boost. Dangerously lean:

Code:
Time (msec)     A/F Sensor #1 (AFR)     Engine Load (Calculated) (g/rev)     Engine Speed (rpm)     Feedback Knock Correction* (degrees)     Fueling Final Base* (estimated AFR)     IAM* (raw ecu value)     Ignition Total Timing (degrees)     Intake Air Temperature (F)     Knock Correction Advance (degrees)     Manifold Relative Pressure (Corrected) (psi)     Mass Airflow (g/s)     Primary Open Loop Map Enrichment* (estimated AFR)     Primary Wastegate Duty Cycle (%)     Target Boost* (psi relative sea level)     Throttle Opening Angle (%)
46099     14.81     0.94     3696     0     14.11     16     38     115     12.5     3.92     58.81     14.31     44.71     11.56     28.24
46166     16.65     0.95     3680     0     13.92     16     37.5     115     12     4.06     59.83     14.1     44.71     11.58     28.63
46265     19.52     0.96     3704     0     13.86     16     37.5     115     12     4.21     59.83     13.95     44.71     11.6     29.02
46332     19.52     0.98     3754     0     13.7     16     37.5     115     12     4.35     60.87     13.83     44.71     11.6     29.41
46420     19.98     0.99     3750     0     13.54     16     37     115     12     4.5     61.57     13.67     45.1     11.62     30.2
46498     19.64     0.99     3799     0     13.28     16     37     115     11.5     4.64     62.96     13.51     45.1     11.66     31.37
46586     19.18     1.04     3759     0     13.16     16     36.5     115     11.5     5.08     65.05     13.28     45.49     11.7     31.76
46664     18.26     1.03     3780     0     13.14     16     36.5     115     11.5     5.22     64.7     13.23     45.88     11.74     32.55
46741     18.15     1.03     3803     0     12.92     16     36.5     115     11.5     5.37     65.4     13.12     45.88     11.74     32.94
46808     18.15     1.04     3844     0     12.92     16     36.5     115     11.5     5.37     66.97     13.04     45.88     11.76     33.33
46896     17.46     1.04     3854     0     12.88     16     36.5     115     11.5     5.51     67.69     12.94     45.88     11.76     33.73
46974     17.69     1.05     3846     0     12.88     16     36.5     115     11.5     5.51     67.86     12.89     45.88     11.78     33.73
47062     17.23     1.06     3866     0     12.83     16     36.5     115     11.5     5.66     68.8     12.9     45.88     11.78     33.73
47140     17.57     1.05     3908     0     12.8     16     36.5     115     11.5     5.66     68.42     12.86     46.27     11.78     34.12
47217     16.88     1.04     3945     0     12.82     16     35.5     115     10.5     5.8     68.42     12.85     46.27     11.8     34.12
47306     16.88     1.06     3937     0     12.79     16     35.5     115     10.5     5.8     69.54     12.8     46.27     11.8     34.12
47383     17.11     1.05     3958     0     12.78     16     35.5     115     10.5     5.8     69.54     12.79     46.27     11.8     34.12
47483     17.11     1.04     3998     0     12.77     16     35.5     115     11.5     5.8     69.36     12.78     46.27     11.8     34.12


For easier access, the full log is online at: https://docs.google.com/spreadsheet/ccc ... FlFWFBuOHc

The snippet above starts at row 720. This particular log does not have TUNA (wideband) data in it, but the A/F Sensor #1 column aligns well with what I'm seeing via the wideband.


Other bits to note: Fuel pressure seems normal, and is rising with boost, and I have no CEL codes. The car runs 93 octane (10% corn.) I suspect it's an air-leak post-MAF, but I haven't been able to find one using eyes, ears, hands, and a can of carb cleaner.

My question for you guys (other than general ideas), is whether any of the number ratios seem off. At ~1.0 Engine Load (g/rev), ~3800 RPM, it's showing Manifold Relative Pressure (Corrected) of ~5.22 psi and Mass Airflow at 65 g/s. I feel like if I knew what I was looking for, then a vacuum leak post-MAF should show more manifold pressure for a given MAF reading than it should.

Any ideas or suggestions on what to do next? I'm tempted to build one of those DIY-PVC intake pressure testers...


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 Post subject: Re: 2002 USDM WRX going lean on boost (FIXED: fuel injector)
PostPosted: Mon Nov 26, 2012 11:22 pm 
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Joined: Wed Oct 17, 2012 10:19 pm
Posts: 2
In case anyone is searching for something similar, I thought I'd post my final fix. After testing the intake, replacing hoses, and lots of debugging, I swapped-in some different fuel injectors (scaled for them) and the problem went away. Without getting the old injectors tested, we'll never know for sure; but for now, the final call is a bum fuel injector.


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