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Thread: P0171 - Diagnosis Help

  1. #1
    Junior Member
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    Default P0171 - Diagnosis Help

    Got a few questions for the masses:

    Recently purchased an 09 GT with 9500 miles. Car runs great, sounds great, but was 'dyno tuned' prior to my purchase. I was curious today so I threw my BlueDriver OBD reader on it and it is pulling the 'P0171 System Too Lean Bank 1' with short drives, not going over 25 MPH.

    Modifications are as follows:
    • Kooks LTH
    • SLP Loudmouth Exhaust
    • Rotofab Intake


    I'm fairly mechanically inclined, just need some direction. Does it make sense that the reader is pulling the P0171 but not triggering the CEL? Is this something that could have been tuned to not display?

    I feel like I hear air, but I did some poking around and couldn't really find anything. Used a long oil funnel to help listen. Seemed to get loudest over the center of the intake manifold where my PCV tube is routed or the back of the motor. Checked out some of the hard vacuum lines and didn't see any cracks. The areas surrounding each injector did look dark, plausible that I need new O-rings due to the low mileage but didn't hear air coming from this area.

    Exhaust manifold leaks could cause this from things I've read; is there a good/easy way to check for this? With how little miles has been put on since installation, I don't SEE anything wrong, but doesn't mean there isn't a leak.

    Checked my fuel trims on the way to work this morning. Drive was 10 minutes, was at operating temperature by arrival, and I gave it a few 3,000 RPM accelerations. The P0171 code shows under the ECM codes, but will not read under the CEL codes or illuminate the CEL. The codes haven't been cleared for the last ~400 miles.

    Bank 1 STFT (HIGH): 10.2%
    Bank 1 STFT (LOW): -7.8%
    Bank 2 STFT (HIGH): 10.9%
    Bank 2 STFT (LOW): -8.5%

    Bank 1 LTFT (HIGH): 6.3%
    Bank 1 LTFT (LOW): -0.8%
    Bank 2 LTFT (HIGH): 4.7%
    Bank 2 LTFT (LOW): -0.8%

    Google Drive link to the report: https://drive.google.com/file/d/0B7f...ew?usp=sharing

    Going to do a little more reading while I wait for some/any input.

  2. #2
    VIP Member Kermit's Avatar
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    It's been so long now that I got my Kooks but I think going with headers, it will give you this code. I think the bank 1 sensor has to be electronically turned off via a tune to prevent this code. Maybe they forgot to do that?
    Again, I can be COMPLETELY wrong about that code. I just remember a code will be thrown if you get headers.
    2009 G8 GT MGM.
    Performance - 1900 MagnaCharger , Lunati Cam, RCR Ported Heads, Intake and TB, FAST #65 Injectors, CTS-v fuel pump, Kooks 1 3/4" LT and Catted X-Pipe, Pypes Violator Axel-Back, Roto Fab CAI, RX Oil Catch Can, Pedders XA's & Track II Bushings, BMR Sub Frame Connectors, Sway Bars & Rear Control Arms, 19 Inch Staggered (8.5 front/9.5 Rear) VMR 810 Wheels, DBA 4000 Sloted Rotors with Hawk HPS Pads & Russels Brake Lines, Camaro 3.27 Diff, Gforce Axles.
    Cosmetic - Partially De-badged Rear, 6.0L Badges, Tinted Side, Rear Markers & Tail Lights, 35% Tint, Auto-dim Mirror, Spencers 6K 35W & 5K 25W Fog HIDS, Blacked Out Door Chrome, Vagas Nates 3 Gauge Pod W/Interceptor Gauges, Color Matched GXP Diffuser, Shark Fin Antenna, V-LEDs on Side/Rear Markers, Brakes & Back Ups Lights, MM Carbon Fiber Rear Spoiler


    1/4 mile 10.917 at 130.44mph 564 RWHP 568 Torque.

  3. #3
    Moderator, Retired -Ray-'s Avatar
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    If you don't have a MIL lit, I wouldn't worry about it.
    Just make sure you aren't getting unmetered air from the intake at the maf.
    Rest in Peace Charlie!

    BMR, Brembo, Circle D, Comp Cams, Crazy Paul's Holden parts,
    Gforce axles, GRRRR8.net SS bolt kit and heater hoses, LandSpeed Development,
    Livernois, Lunati, Pedders, White auto media
    Under more construction.


    Just a GT


    Quote Originally Posted by RichsGreyGT View Post
    this site is hardcore modding central.

  4. #4
    Addicted Member RichsGreyGT's Avatar
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    Mine was throwing that code AND also the CEL. Started happening after I cleaned my Vararam filter.

    I ended up changing the MAF, spark plugs, wires and the upstream O2 sensor. Code is gone.

    Yes I threw money at the problem. I love spending money~! haha
    MGM '09 G8 GT, RCR tuned, RCR cam (223/231 .625/.622 111+0 ), PRC 250CC heads 65cc chambers, RCR "ram air" intake, & ported TB; Spectre 102mm MAF/LS7 card, HSRK, DT headers, Vararam with RCR type air wedge, Solo Mach CB, 3.45 gears & Yank 3200SS stall

  5. #5
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    May want to do a injector balance test, one could be spraying weak from car sitting a lot

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