2011 Malibu 2.4 ecotec p0171

Hello, I’m new here

ive been watching the SD videos and learning to use my scanner to figure out this p0171 lean bank one code

heres where I’m at;  I found a rip in the boot between the throttle body and the intake cover which I replaced. A also changed the throttle body because I happened to have a known new working one and the old one was filthy. I’ll clean it for later testing and use. I cleared the code after replacing it and still have a problem. I ran the stft and ltft and my long term is 10 at idol and as rpm’s increase so does the ltft to 29.9. It’s worth mentioning that short term is all over the place from negative to positive. (O2 sensor trying to ajust mixture I assume)  As I learned in the sd videos this is a maf or fuel delivery problem. I changed the mass airflow with the only maf my local Autozone had in stock which happened to be a hitachi.  It didn’t solve the problem. The code returned after clearing and test drive. What’s the chances the hitachi maf sensor is bad?  Should I buy another or should I look at fuel delivery problem?  If fuel delivery problem is this something I can use the scanner for? May scanner although not bidirectional snap on does have some fuel system abilities. What can I look at next on scanner or should I go out and buy or rent a fuel pressure tester?  What do you recommend? I or is there an sd video you’d recommend I watch? 

also worth mentioning i bought the car recently with the existing problem.  So because it’s new to me I don’t know what’s been done prior.  Does this vehicle supposed to have a rear cat? It has upstream o2 then cat on/behind manifold then downstream o2 then flex pipe then pipe to muffler. I drove the car 30 miles home with the mil on. It was a cold day and it ran great other than the check engine light which I checked with scanner and knew it had P0171 code.  When it’s warm out it doesn’t run so great. When it’s cold it seams to run pretty good. 
oh and by the way o2 is reading .81 volts on freeze frame. Isn’t that usually a sign rich not lean? I figured that was possibly the computer trying to compensate the fuel mixture so I pulled the plugs and they had carbon soot and not oil. 
Oh and I almost forgot. This could also be important. On the freeze frame it also says 
Ingnition timing advance for cylinder #1 10*.

I can’t think of anything else. Thanks for your time! 

Ensure that the o2 or A/F sensors are reporting accurately. Look for the calculated load value PID, run the car at W.O.T, and note the percentage. Close to 100 is ideal. You should have a MAF voltage above 4v at W.O.T as well.

I’m sorry to ask a seemingly stupid question but what’s a safe rpm for wot or will my rev limiter protect me from having to worry. I’ve seen Paul use manual shifting 1st gear to test wot. Is that the best way? I assume the wot needs to be under load and that’s why moving 1st?

Also I’m already at 100% calculated load on my freeze frame at only 2100 rpm’s. I knew that had to mean something because none of my other vehicles freeze frames are at 100% and only 2100 rpm’s.

Yes, it is a safe way to do the WOT test. Can you check the fuel pressure? Based on the 100% calculated load value at 2100 RPM, I would say that the maf is reporting accurately. If the MAF were over-reporting, you would have a rich code. To make sure that the freeze data is accurate,run the car at WOT with the selected PIDs: Calculated load, RPM, and O2 sensors, and let us know your findings.
 

I cleared the code after replacing it and still have a problem. I ran the stft and ltft and my long term is 10 at idol and as rpm’s increase so does the ltft to 29.9

Does the code still return? Even if you fixed the problem, the LTFT is going to take some time to correct. If, for example, the STFT is negative 20%  at the same time LTFT is positive 29% (because it remembers needing to add fuel due to the lean condition), that's a total trim of 9% and perfectly acceptable. Even 10% total trim positive or negative wouldn't get me to open the hood. It's important to know what the STFT and LTFT are doing together before continuing.

You make a good point. Would it take a drive cycle long enough for a full im readiness with all its check marks before it corrects? I’m still going to do the wot test monde suggested but your point is a good one. Also if computer is still remembering I’m wondering if after I do the wot test, should I take the negative and positive terminals off the battery and touch them together to clear all memory that simply clearing the codes with my scanner may have missed or don’t you recommend doing that?

I’m still going to do the wot test monde suggested but your point is a good one.

Monde is very smart, he won't steer you wrong.

should I take the negative and positive terminals off the battery and touch them together to clear all memory that simply clearing the codes with my scanner may have missed or don’t you recommend doing that?

I think that's a good idea.

I made a video graph with  02, rpm’s, and calculated load but it’s not uploading. Maybe it’s too big.  Wot seems to be around 4000 rpm’s on this car or because it’s running poorly that’s as high as I could get rpm’s the o2 volts drop to zero at wot and load 100%. I was really hoping to figure out how to upload the video  so you could also hear what it was doing. (I recorded video of scanner with phone.)   you wouldn’t be able to hear the car run if I uploaded the .exe file.  I did record one but have no access to a laptop atm to plug scan tool into.  I’m not sure if telling is as good as seeing it so I’ll keep working on it. 

Ok so I left my other scanner in my truck but this one does have the ability to graph load,o2 and rpm’s.  I don’t have my laptop and can’t get the file small enough to share so I’m going to post a link to the video and see if that works. 

youtube.com/shorts/CPVkTTfdswE?si=hHhBW3XAs_bB9_PX

The video is very poor quality, I can't even tell what PIDs you have there.

Sorry, this reply took so long. I have been so busy at work and with other projects that I only just today got back around to working on this again.
So in this video I had to work with the only scanner on hand. I’ve cleaned it up the best I can so you can see what the pids being used are.



Red=load
Orange=o2
Green=rpm’s

Here’s another video For reference.

Red=stft
Orange=maf
Green=map

Sorry, that's not helpful at all, lol.
So I presume you have been driving the car. Has the code returned?
If it has, the PIDs you need to look at togther are STFT, LTFT, RPM, Loop Status ( because of it's not in closed loop, fuel trim is irrelevant).
IF the engine light is not back on, then you fixed it. Good job 

It’s closed loop. That was already established. We already determined it’s not a vacuum leak too prior to my very first post. Also, no I’m not driving it. It runs great when it’s cold outside but teribble when warm out as it’s been lately. The very last video can be disregarded with stft, map and maf. As I posted it was just a video I uploaded on accident so wrote “just for reference” I should have just wrote “posted by mistake” the pids that monde asked for are in the video above it is the one you should be looking at. I can see it on my end. Maybe you can’t see it? The one with load, rpm and o2. I know someone said it doesn’t seam like it’s the maf with it already being 100% load at 2000 rpm’s but thought I should still post the video anyways because it also said, “assuming is never a good thing”. So if you can see the video, do we now agree that it’s not the maf or is more testing needed? Im a little confused as to where we are at in determining. I thought I still needed to post that wot test for monde and it seems to me that maybe your a little ahead or even a little behind where I thought we where. Would it help you to see the freeze frame? It shows that it’s in closed loop. Also if you could be so kind as to tell me not just what pids are needed, but what we’re testing for because I thought we determined that it’s not a vacuum leak and are now trying to determine if it’s the maf or fuel related.

This is my freeze frame data.  I’ve driven around watching and recording live data and in both the freeze frame and live it’s always been closed loop. Maybe something here could answer what other pids might be needed. 

My apologies, I only just noticed it’s reported everything in metric. There are 5 more pictures of the freeze frame I hadn’t yet uploaded when I noticed it was set to metric. If you need to see freeze frame data in standard (all 11 pictures)  I’ll have to switch the scanner to standard and get new photos. Let me know if you want to see all 11 pictures of the freeze frame in standard measurement system. Also let me know exactly where we are in the process, what we need to determine and what pids we need next. Keep in mind that I can only graph 3 pids at once. I am happy to take a video of 3 then another 3 and upload them all together. Just let me know which 3 at a time on each graph screen is needed.

New development. Remember how we talked about disconnecting the battery to clear the capacitors and get it back to factory defaults to make sure the computer isn’t remembering the old maf sensor? (Or rather the old fuel trims) I just discovered this car has 3 ecm fuses. One of them is a ecm batt fuse!  Does this mean I need to pull one or more of these ecm fuses?

Ok, so then the answer is "yes, the code has returned?"

Your answer about clearing the codes and code coming back is simply this; The wot test was done with the factory maf. I did decide to move on after waiting for comments on the wot test and try clearing the codes after putting in the new hitachi maf sensor back in. They wouldn’t clear with my scanner so I used a buddy’s. Wouldn’t clear with his. I pulled battery terminals from battery touched them together and that didn’t clear the codes either. Left them off for an hour. No joy. Pulled the ecm and ecm batt fuses and left them out for 30 minutes. Still won’t clear the code. Now the car turns over but won’t even start. It’s a reall head scratcher! I did graduate from an automotive school back in 91 so I’m experienced but out of practice and back then cars weren’t the rolling computers that they are today. Back then you could roll around for years here in the state of Michigan (no emission tests) with a bad 02 sensor and it wouldn’t affects it’s drivability like today. As a dual major in business management and automotive I hit the ground running as a service manager straight out of school and have become rusty and inexperienced on these new cars with vvt soilnoids instead or egr valves and lots of other changes too. It’s just a hobby for me these days but this one isn’t fun hobby kind of repair anymore. It’s very close to becoming a parts car. Although I’ve never given up on a repair and don’t want to start now.