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2006 chevy trailblazer_ls
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Discussion Starter #1
Long time reader first time poster looking for an answer. I recently had a rough running engine (P0017 code) I changed the Camshaft Position Actuator Solenoid and it was damaged, I also clean the throttle body it was dirty, and changed my air filter which was very dirty. Now I’m get a P0171 code (System too Lean), these are the parameters.

System too Lean (Bank 1)
Fuel sys 1 CL
Fuel sys 2 NA
Calc Load (%) 28.6
ECT (deg C) 88
STFT B1 (%) -1.6
LTFT B1 (%) 24.2
MAP (kPa) 34
Eng RPM 594
Veh Speed (km/h) 0
Spark Adv (deg) 5.0
IAT (deg C) 20
MAF (g/s) 4.24
TPS (%) 13.7
Air Status NA

My Trailblazer is a 2006LS with a 4.2 liter engine and 100000 KM on it. Thank you for your help.

MaxPower
 

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2005 gmc envoy_sle_xl
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Long time reader first time poster looking for an answer. I recently had a rough running engine (P0017 code) I changed the Camshaft Position Actuator Solenoid and it was damaged, I also clean the throttle body it was dirty, and changed my air filter which was very dirty. Now I’m get a P0171 code (System too Lean), these are the parameters.

Eng RPM 594

My Trailblazer is a 2006LS with a 4.2 liter engine and 100000 KM on it. Thank you for your help.
Engine RPM is too low. It should be 650 if I am not mistaken. A lean condition could be a slow O2 sensor or vacuum leak. Also have you disconnected the battery to reset the system after cleaning the TB? How is the fuel pressure?

A code P0171 may mean that one or more of the following has happened:
•The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters may cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
•There could be a vacuum leak downstream of the MAF sensor.

Possible Solutions

Possible solutions include:
•In the vast majority of cases, simply cleaning the MAF sensor does the trick. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling
•Inspect all vacuum and PCV hoses, replace if necessary
•Check for a dirty fuel filter and proper fuel pressure
 

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Discussion Starter #3
Thanks, Ralph_T

I took my MAF sensor out and cleaned it tonight, I will disconnect the battery again in the morning for 45 minutes, I had done this after I cleaned my throttle body for 20 to 25 minutes maybe it wasn't long enough? I’ll be driving it tomorrow I'll see what happens.
Could it be that the air filter was very dirty so it was not get proper airflow therefore running rich, and now with the new air filter the computer thinks it is running lean or has not adjusted itself?

MaxPower
 

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Thanks, Ralph_T

I took my MAF sensor out and cleaned it tonight, I will disconnect the battery again in the morning for 45 minutes, I had done this after I cleaned my throttle body for 20 to 25 minutes maybe it wasn't long enough? I’ll be driving it tomorrow I'll see what happens.
Could it be that the air filter was very dirty so it was not get proper airflow therefore running rich, and now with the new air filter the computer thinks it is running lean or has not adjusted itself?

MaxPower
Nah, I am sticking to the MAF being the culprit. It shouldn't matter how much air you are getting. Only a loss of power in the higher band would result. The key here is that the engine thinks it is getting less air. This would create a lean condition. Especially when the computer has your right foot and the MAP sensor to guess engine demand.

The MAP sensor and the Throttle Position Sensor tell the PCM, "Hey. I am going full throttle! Lets give it more gas".. But the MAF sensor is telling the computer "I am showing this much air going in. Do with it as you see fit." But the computer says "Oh crap I guess I need to lean out the injectors because I aint getting enough air". Then the O2 sensor tells the computer "Your running too lean dude." So then the computer increases fuel and then the cycle starts all over. Something like that.

It wouldn't be a bad idea to change the O2 sensor while your at it and throw in some Techron Concentrate in your tank. Then you should be covered on all ends.
 

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Discussion Starter #5
It wouldn't be a bad idea to change the O2 sensor while your at it and throw in some Techron Concentrate in your tank. Then you should be covered on all ends.

Is there two O2 sensor? If so, is it the upsrtream sensor that should be replaced?

MaxPower
 

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Discussion Starter #7
Drove it today still getting the P0171 code after cleaning the MAF sensor. Checked intake bolts to see if they were loose, some were a bit. Tried to get O2 sensor out tonight but it is seized in pretty good will be work on it tomorrow. I also plan to pickup some Techron Concentrate if I can get that in Canada not sure I’ll look.

MaxPower
 

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Discussion Starter #10
Does anyone have any ideas for get the O2 sensor out, mine is seized in, I can't seem to get to loosen. I’ve spray it with penetrating oil and left it for quite awhile. Would it help if run the engine and have the exhaust manifold hot?

Thanks, MaxPower
 

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Does anyone have any ideas for get the O2 sensor out, mine is seized in, I can't seem to get to loosen. I’ve spray it with penetrating oil and left it for quite awhile. Would it help if run the engine and have the exhaust manifold hot?

Thanks, MaxPower
Yes, it helps to have the exhaust manifold a little hot when removing the O2 sensor.

PB blaster + heat should do it, it worked for me.
 

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Discussion Starter #13 (Edited)
Yes, it helps to have the exhaust manifold a little hot when removing the O2 sensor.

PB blaster + heat should do it, it worked for me.
Tried this, no luck getting my O2 sensor out. I'm going drive it for a bit and see if tightening up the intake bolts made a difference. I'll let you know if the code comes back.

MaxPower
 

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Tried this, no luck getting my O2 sensor out. I'm going drive it for a bit and see if tightening up the intake bolts made a difference. I'll let you know if the code comes back.

MaxPower
Any updates on this? I've been having issues with the cyl 4 misfire from water getting between the hood and cowl. Changed the plugs last July when one of them cracked from being so rusted up. Started doing it again couple weeks ago. Put the updated hood seal on it, and dried it out. Didn't get rid of the misfire though. Check engine light came on today while I was bringing it into work today so I can work on it. Figured it was for the misfire since it was pretty bad. No misfire codes, just the P0171. Going to change the #4 coil and see if that fixes the misfire.
 

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Discussion Starter #15
Been driving it for a week with NO codes. I did end up changing my plugs at the same time as I tightened up my intake bolts, after this everything seems to be good for now.

I would like to thank everyone for their help and sharing their knowledge, it is much appreciated.

MaxPower
 

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seafoam

I can strongly suggest that SEAFOAM is probably WAY better to clean your fuel system, yhis stuff is amazing....I can also suggest PB pentrating oil, it's one of the best I've used.
 

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Been driving it for a week with NO codes. I did end up changing my plugs at the same time as I tightened up my intake bolts, after this everything seems to be good for now.

I would like to thank everyone for their help and sharing their knowledge, it is much appreciated.

MaxPower
How did you get your oxygen sensor out? The nut on mine is stripped. Planning to use a pipe wrench tomorrow. BTW, compnine part number for the O2 is AC Delco 213-3539. Sorry, I gave you the part number for my truck a few posts back. Let me know.:yes:
 

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Finally got my oxygen sensor out using by using wd40 and a 10" pipe wrench I bought at Harbor Freight. Installing the new sensor was a bear as well. The threads appeared to be clean. Not sure why mine was difficult seeing how others posting here are only using a box end wrench.:confused:
 

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Discussion Starter #19
How did you get your oxygen sensor out? The nut on mine is stripped. Planning to use a pipe wrench tomorrow. BTW, compnine part number for the O2 is AC Delco 213-3539. Sorry, I gave you the part number for my truck a few posts back. Let me know.:yes:
Never ended up replacing it, could not get it out.
 

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Discussion Starter #20
I can strongly suggest that SEAFOAM is probably WAY better to clean your fuel system, yhis stuff is amazing....I can also suggest PB pentrating oil, it's one of the best I've used.
Thanks, I tried the PB pentrating oil, did not do it for me. I haven't used the anything in my fuel system yet but thanks. I was thinking about the seafoam, I can not get the chevron stuff in Canada.
 
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