[SOLVED] Code P0171 after changing my spark plugs. - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum



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Go Back   Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum > 2002 - 2009 TrailBlazer/Envoy Tech > 02-09 Vortec 4.2L I-6 Engine and Drivetrain > Air Induction

Air Induction Performance Air Intake/Air Induction Modifications

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  #1  
Old 05-12-2011, 12:21 PM
lsx-geezer lsx-geezer is offline
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Code P0171 after changing my spark plugs.

For once, I'm not asking for help. I just wanted to pass along some experience I gained recently. I have a 2006 TB LS with the 4.2 motor. It has about 96K on the clock and I felt like it was time to change the plugs before a long trip. After pulling off the required air and stuff, the plug change was uneventful and I put everything back as it was (or so I thought). During the plug change I noticed that the throttle body was dirty, so I got out my trusty carb and choke cleaner and went to work on it. It cleaned up real nice. Unfortunately, shortly afterward the P0171's started showing up as alarms on my Ultra-Gauge. I started searching my memory of the work I had done and thought about the carb cleaner. I had forgotten that there are solvents that are much safer to use on modern vehicles and I thought maybe I had messed up a sensor. I didn't have a lot of time to pull things apart again before the trip so I just kept resetting the trouble codes and left. While driving for hours at Interstate speeds, the trouble codes did not appear, but when I stopped, they popped up again. Finally when I arrived home, I took apart the air box on top of the engine and looked at every connection trying to see what I had done wrong. When I turned over the air box, I saw the problem. I hadn't noticed the small hose that connects the air box with the engine. Since I hadn't noticed it when I removed the air box, I didn't connect it again when I re-installed the box. When I found the problem and corrected it, the P0171's disappeared.
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  #2  
Old 05-16-2011, 02:12 PM
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deathmate deathmate is offline
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Do you happen to have a pic of that hose. I got the same code popping up after I cleaned the Intake. Its been driving me nuts trying to find out why the code keeps showing.
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Old 05-16-2011, 02:55 PM
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deathmate deathmate is offline
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Found It!!!!!!!!!!!!!!!!!! I thought that was just a excess air release hose or whatever. I hope that fixs my prob.

Was looking in the "Clean Throttle Body" post and saw the pics in Step 8.
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  #4  
Old 10-26-2011, 02:53 AM
jsafe jsafe is offline
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Ha me too .. l got in a hurry .. fixed now thnx guyz
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Old 10-26-2011, 05:28 AM
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Did you get an SES light? When I first bought my truck I drove around for a few weeks with this hose off before realizing it and I never got an SES light to come on.
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  #6  
Old 10-26-2011, 06:20 AM
Blazin_Trails Blazin_Trails is offline
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Quote:
Originally Posted by gmac310 View Post
Did you get an SES light? When I first bought my truck I drove around for a few weeks with this hose off before realizing it and I never got an SES light to come on.
All the other guys have in this thread have 06's, 06+ have different hoses and a MAF sensor on the air intake.
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Old 10-26-2011, 05:26 PM
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gmac310 gmac310 is offline
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Quote:
Originally Posted by Blazin_Trails View Post
All the other guys have in this thread have 06's, 06+ have different hoses and a MAF sensor on the air intake.
Gotcha, didn't even notice they were a different year.
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Old 06-03-2012, 03:27 PM
mklim mklim is offline
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Quote:
Originally Posted by lsx-geezer View Post
For once, I'm not asking for help. I just wanted to pass along some experience I gained recently. I have a 2006 TB LS with the 4.2 motor. It has about 96K on the clock and I felt like it was time to change the plugs before a long trip. After pulling off the required air and stuff, the plug change was uneventful and I put everything back as it was (or so I thought). During the plug change I noticed that the throttle body was dirty, so I got out my trusty carb and choke cleaner and went to work on it. It cleaned up real nice. Unfortunately, shortly afterward the P0171's started showing up as alarms on my Ultra-Gauge. I started searching my memory of the work I had done and thought about the carb cleaner. I had forgotten that there are solvents that are much safer to use on modern vehicles and I thought maybe I had messed up a sensor. I didn't have a lot of time to pull things apart again before the trip so I just kept resetting the trouble codes and left. While driving for hours at Interstate speeds, the trouble codes did not appear, but when I stopped, they popped up again. Finally when I arrived home, I took apart the air box on top of the engine and looked at every connection trying to see what I had done wrong. When I turned over the air box, I saw the problem. I hadn't noticed the small hose that connects the air box with the engine. Since I hadn't noticed it when I removed the air box, I didn't connect it again when I re-installed the box. When I found the problem and corrected it, the P0171's disappeared.
I love this forum. This just fixed my issue. I missed it after cleaning my TB. Thanks!!!
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Old 01-07-2013, 08:58 PM
jack0723 jack0723 is offline
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Code P0171

Hello all. I just want to share my experience with code P0171 in hopes it helps other out there with the same situation.

This past week, the temp in New York was down between 2F and 5F in the morning, reaching a balmy 15F in the afternoon. That particular day my wife came home from work and told me a yellow light on in the dash came on and the engine was running rough. Sure enough it was the check engine light. I scanned the PCM and found the code P0171 for lean mixture. I did the obvious looking for vacuum leaks, sprayed the intake listening for a RPM change and watching the LTFT, but found nothing. Long story short, I cleaned the MAF and the fuel trims changed for the better - temporarily - so I replaced the MAF. Same problem. Next was the O2 sensor since it seemed slow switching and was not reaching more than 700 mv. I also cleaned the throttle body and plate - still no change. I searched online and found MANY reason and fixes, the one most common being loose intake manifold bolts. Since I already sprayed the intake connections with carb cleaner before, I didn't consider this a problem, but not wanting or liking to just throw (more) parts at it I decided to check the bolts. First, they are not easy to get to, but well worth checking, as most were loose. The last one on cylinder #6, which is the hardest to access was the loosest. I couldn't actually see it, but it was unthreaded at least 1/8". After tightening all the bolts (no I didn't torque them), I started the engine and monitored the LTFT's and they dropped like a rock. I will replace the intake gasket once the weather changes, but for now, the readings are good enough to leave it alone. LTFT readings before the fix were between 12% and 17% at idle, and around 9% when cruising. Readings now are around 7-8% at idle and drifting between 2% to -4% while crusing. I hope this information helps someone out there.

Jack
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  #10  
Old 07-13-2013, 12:34 PM
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jdod23 jdod23 is offline
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Dang this hooked me up too

I even bought a scanner to diagnose. Thanks for posting!
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