PO171 and PO172??

[benjaminblazer]

Having an issue with my 06 LS Trailblazer, Lean System Bank 1 and Rich System Bank 1. Not sure how this is possible, my guess was a bad sensor however everything iv seen says Oxygen Bank 1 sensor which i just replaced last year with a ACDelco GM Genuine. Not that it’s not possible but i figured it probably didn’t go bad that soon. My next guess was the MAF sensor since i just recently replaced my power steering pump(took off intake and unplugged MAF). My idle RPMs are also stuttering under 700 then jumping back during idle.
Thanks for reading, appreciate any feedback and or advice
Here are the codes

 

[TJBaker57]

Does that scanner read out freeze frame data?

And I don't see any indication of the status of the displayed code(s). (current, history, pending, etc.)

How about a live data record? Does the scanner have that capability?

 

[benjaminblazer]

Does that scanner read out freeze frame data?

And I don't see any indication of the status of the displayed code(s). (current, history, pending, etc.)

How about a live data record? Does the scanner have that capability?

Does not, that 3rd code i think means stored, the other two are current though, its only a 30 dollar one from amazon while im away from my main one at home.

 

[TJBaker57]

that 3rd code i think means stored

On a second look I see the "pd". Likely means "pending".

There is no "stored" status as far as GM is concerned here on these vehicles. No such term on a Tech 2.

I might guess that the word "stored" might be substituted by some for the "history" status??

 

[benjaminblazer]

On a second look I see the "pd". Likely means "pending".

There is no "stored" status as far as GM is concerned here on these vehicles. No such term on a Tech 2.

I might guess that the word "stored" might be substituted by some for the "history" status??

Yeah probably pending, however on my other OB2 it says stored and pending for that code so..

 

[mrrsm]

A Few Suggestions:

(1) If you have a VERY Dirty Air Filter and a likewise, contaminated MAF sensor that needs a Good Cleaning with CRC MAF Solvent... this area is THE "LHF" Place to Start (Low Hanging Fruit) looking for issues with Sketchy A/F activity:

Screen Capture via a YT Video:



(2) Get a Can of Starter Fluid and with a Fire Extinguisher at hand, Spray along the Intake Manifold Flange at the Head Intake Ports while the Engine is Idling and see if the RPM elevates. Do --NOT-- Over-Spray with the Starter Fluid! Do --NOT-- Do this Test inside of an enclosed -closed Garage

(3) If the RPM goes up suddenly... Visit all of the "Trapped Fasteners" holding the Intake Manifold to the Head... and Tighten them all back down to 89 Inch Pounds... and NO MORE. The Fasteners are MEANT to Bottom Out on a Bolt Ledge that WILL Snap Off if too much Torque is applied. It may come down to cases that replacing the *Flattened* Rubber "O" Ring Style Gasket Set to put things right.

(4) THIS is not a Trivial Job since gaining access to the staggered 10mm IM Fasteners to R&R the IM requires jacking up the SUV, Using a Jack Stand to support the Vehicle and removing the Left Front Wheel in order to access the lower IM Bolts through the Wheel Well and work on the one near the Firewall with a combination of Ratchet, U-Joint and Socket to get at to them. There are other like-minded Threads with more ideas on how to do this part properly.

(5) If the Upstream 02 Sensor is failing, or if there are MAJOR Air Leaks along the Exhaust Manifold from having Broken EM Bolts... then Random Ingested, Unregulated Air can skew the A/F responses via the O2s actually doing their jobs correctly.

(6) A Leaking SAIS Gasket or Stuck SAIS Solenoid (Passenger Side of the Engine Head) can also cause weird P0171 issues by allowing unregulated AIR to get access to the Q2 Sensors in the exhaust gas air stream.

 

[benjaminblazer]

A Few Suggestions:

(1) If you have a VERY Dirty Air Filter and a likewise, contaminated MAF sensor that needs a Good Cleaning with CRC MAF Solvent... this area is THE "LHF" Place to Start (Low Hanging Fruit) looking for issues with Sketchy A/F activity.

(2) Get a Can of Starter Fluid and with a Fire Extinguisher at hand, Spray along the Intake Manifold Flange at the Head Intake Ports while the Engine is Idling and see if the RPM elevates. Do --NOT-- Over-Spray with the Starter Fluid! Do --NOT-- Do this Test inside of an enclosed -closed Garage

(3) If the RPM goes up suddenly... Visit all of the "Trapped Fasteners" holding the Intake Manifold to the Head... and Tighten them all back down to 89 Inch Pounds... and NO MORE. The Fasteners are MEANT to Bottom Out on a Bolt Ledge that WILL Snap Off if too much Torque is applied. It may come down to cases that replacing the *Flattened* Rubber "O" Ring Style Gasket Set to put things right.

(4) THIS is not a Trivial Job since gaining access to the staggered 10mm IM Fasteners to R&R the IM requires jacking up the SUV, Using a Jack Stand to support the Vehicle and removing the Left Front Wheel in order to access the lower IM Bolts through the Wheel Well and work on the one near the Firewall with a combination of Ratchet, U-Joint and Socket to get at to them. There are other like-minded Threads with more ideas on how to do this part properly.

(5) If the Upstream 02 Sensor is failing, or if there are MAJOR Air Leaks along the Exhaust Manifold from having Broken EM Bolts... then Random Ingested, Unregulated Air can skew the A/F responses via the O2s actually doing their jobs correctly.

(6) A Leaking SAIS Gasket or Stuck SAIS Solenoid (Passenger Side of the Engine Head) can also cause weird P0171 issues.

Here is this, don’t know how much this cold air intake affects the codes but my MAF is also missing a screw. However, with this said i cleaned off the MAF pretty recently as well as the intake, trying to get a normal one though.
Also for your 3rd suggestion, are you talking about the top piece that says 4.2 vortec? Or something under that, because i’m missing a screw for that as well.

 

[TJBaker57]

"Cold Air Intake"

I will never understand how it could be thought that the air will somehow magically be colder after passing through the potentially hot A/C condenser coil, the assuredly hot radiator and being adjacent to the certainly very hot exhaust manifold and engine than it would otherwise be when taken from in front of all that hot stuff as the factory air intake does.

 

[mrrsm]

No... Not the Air (Box) Plenum which joins the Throttle Body to the Air Inlet Tube from the Cold Air Intake (Very Likely allowing the MAF Sensor Elements to become VERY Dirty, too).

The Trapped Fasteners I am referring to are arrayed along the Plastic Flange of the Intake Manifold that has Three Paired Figure *8* Shaped Rubber Grommet Gaskets that will eventually Flatten Out while oscillating (Floating on the Rubber Grommets) with the Throttle Body balanced on the Inner Portion of the IM and the PCM mounted on the opposite site as a counter-weight:



With BAD MOTOR Mounts on High Mileage Engines... Over time Excessive Vibrations impacting those Intake Port Gaskets will --flatten them all out-- so much so that Ambient Air will get sucked in at random locations along the entire length of any Loosened IM Flange and FUBAR the A/F Ratios causing P0171 and P0300 Codes to be thrown.

PS... Based upon the apparent poor condition of the After Market Cold Air Intake Filter... it is very likely that the Intake Throttle Body deserves a decent R&R and a "Bench Top" Cleaning as well.

The problem with this type of Filter is that they always allow an enormous amount of Dust and Dirt to By-Pass Proper Filtration and that is an invitation for excessive In-Cylinder Dust and Dirt Contamination that will enhance Cylinder Wall and Piston Rings to Wear.

 

[benjaminblazer]

"Cold Air Intake"

I will never understand how it could be thought that the air will somehow magically be colder after passing through the potentially hot A/C condenser coil, the assuredly hot radiator and being adjacent to the certainly very hot exhaust manifold and engine than it would otherwise be when taken from in front of all that hot stuff as the factory air intake does.

Yeah i don’t get it either, i also don’t get why the owner before me put this on here, knowing it was a v6 not even a SS.

 

[benjaminblazer]

No... Not the Air (Box) Plenum which joins the Throttle Body to the Air Inlet Tube from the Cold Air Intake (Very Likely allowing the MAF Sensors to become VERY Dirty, too).

The Trapped Fasteners I am referring to are arrayed along the Plastic Flange of the Intake Manifold that has Three Paired Figure *8* Shaped Rubber Grommet Gaskets that will eventually Flatten Out while oscillating (Floating on the Rubber Grommets) with the Throttle Body balanced on the Inner Portion of the IM and the PCM mounted on the opposite site as a counter-weight:

View attachment 115169

With BAD MOTOR Mounts on High Mileage Engines... Over time Excessive Vibrations impacting those Intake Port Gaskets will --flatten them all out-- so much so that Ambient Air will get sucked in at random locations along the entire length of any Loosened IM Flange and FUBAR the A/F Ratios causing P0171 and P0300 Codes to be thrown.

PS... Based upon the apparent poor condition of the After Market Cold Air Intake Filter... it is very likely that the Intake Throttle Body deserves a decent R&R and a "Bench Top" Cleaning as well.

The problem with this type of Filter is that they always allow an enormous amount of Dust and Dirt to By-Pass Proper Filtration and that is an invitation for excessive In-Cylinder Dust and Dirt Contamination that will enhance Cylinder Wall and Piston Rings to Wear.

Gotcha, going to try these recommendations tonight, here are some more codes and info on the car with my other scanner!

 

[mrrsm]

Regarding the P0171 and the possible involvement of the SAIS Solenoid becoming inoperative, this is arguably the BEST Instructive Diagnostic Video covering that component. Here are the "One Over The World" Views of the SAIS System:

The reason I like this Wells Video is because THAT Dude is part of the Regular Crew that produces Videos for "Trained By Techs" ...mostly for the use of In-Depth Oscilloscope Diagnostics, essential for this kind of work.

This information relates to another Unsolved Thread by the same name:

Help with PO171 Error Code

Hello All, I have been repeatedly been getting that pesky PO171 error code on my 2006 Ascender with the 4.2 engine. and around 60,000 miles. The following is what I have done so far, in order. 1. Had dealer re-flash ECM with latest version upgrades (free under open campaign). 2. Clean air box...

gmtnation.com

 

[Mooseman]

(2) Get a Can of Starter Fluid and with a Fire Extinguisher at hand, Spray along the Intake Manifold Flange at the Head Intake Ports while the Engine is Idling and see if the RPM elevates. Do --NOT-- Over-Spray with the Starter Fluid! Do --NOT-- Do this Test inside of an enclosed -closed Garage

I would caution AGAINST using starting fluid. It is too volatile and flammable as well as possibly put you to sleep (ether). Use carb or non-chlorinated brake cleaner instead but still do this outside and have an extinguisher handy.

 

[Mooseman]

Your LTFT is whacked. Seems to be running super rich and pulling back fuel (LTFT -24.2%). I would ditch that HAI (Hot Air Intake) and get a stock cover, hose and new filter as that filter doesn't look too healthy. I would also get some MAF cleaner and clean it as those oiled filters have a tendency of contaminating it.

 

[budwich]

You posted a "running MAP" reading from your freeze frame data. Post that PID for engine OFF / key ON. That "should be" your "base barometric" reading for your vehicle. That one helps determine the amount of correction in the speed density system.

 

[mrrsm]

As per @TJBaker57 's suggestion in Post #8... There IS a Decent, Complete Air Intake System for a 2005 Chevrolet Trailblazer (Nice!) Available over on eBay for only $110.00 (OBO) with FREE S&H -=right now=- that will help to normalize things again under the hood:

2005 Chevrolet TRAILBLAZER 4.2-L COMPLETE AIR CLEANER BOX ASSEMBLY OEM | eBay

This part was removed from a 2005 Chevrolet TRAILBLAZER 4.2-L and may interchange with lots of different years and models so do your own research. It is in fine usable working order see picture nice piece.

www.ebay.com

 

[Mooseman]

Or even better, from a pick-n-pull yard if you have one nearby. Usually much cheaper and you can be sure the have the proper one.

 

[benjaminblazer]

Your LTFT is whacked. Seems to be running super rich and pulling back fuel (LTFT -24.2%). I would ditch that HAI (Hot Air Intake) and get a stock cover, hose and new filter as that filter doesn't look too healthy. I would also get some MAF cleaner and clean it as those oiled filters have a tendency of contaminating it.

That is the plan, been looking around for one for awhile and can’t find my right one. 06 and up. All want upwards of $100 that’s just not worth it for me right now.

 

[benjaminblazer]

You posted a "running MAP" reading from your freeze frame data. Post that PID for engine OFF / key ON. That "should be" your "base barometric" reading for your vehicle. That one helps determine the amount of correction in the speed density system.

Car was off when i scanned.

 

[benjaminblazer]

As per @TJBaker57 's suggestion in Post #8... There IS a Decent, Complete Air Intake System for a 2005 Chevrolet Trailblazer (Nice!) Available over on eBay for only $110.00 (OBO) with FREE S&H -=right now=- that will help to normalize things again under the hood:

2005 Chevrolet TRAILBLAZER 4.2-L COMPLETE AIR CLEANER BOX ASSEMBLY OEM | eBay

This part was removed from a 2005 Chevrolet TRAILBLAZER 4.2-L and may interchange with lots of different years and models so do your own research. It is in fine usable working order see picture nice piece.

www.ebay.com

View attachment 115219

Doesn’t fit an 06, maf sensor on the bottom not the top by the plug cover.

 

[budwich]

Car was off when i scanned.

The information that you posted in #11 is not live data but stored / freeze frame data from the coding.... RPM was 604.

 

[benjaminblazer]

The information that you posted in #11 is not live data but stored / freeze frame data from the coding.

what do i do different? something on the scanner

 

[benjaminblazer]

After finding a filter, hose, and box in almost new condition at a pick and pull for only $20, i installed it right away. Threw away that crap cold air intake and started the engine. RPM Rev up and down has gone away. Cleared engine codes, knock on wood drove around 200 miles now with no codes. Thanks everyone for the help, while this might not be the code problem solver, it definitely helped my idle problem!