Extreme lean condition confusion

I have tried a few tunes, I got this one to where it felt good all over, I was even able to liven up lower rpm/speed pulls by what felt like a lot, however, suddenly now I am getting a maxed lean condition when I am coasting or going a steady speed and not applying the throttle. If I just touch the throttle it goes away and I have been chasing it for two days.

This is a bone stock 2007 Trailblazer SS w/a hiflow air filter and air box mod only.
The number looked good and it felt great except this lean issue that threw DTC.

Any help is much appreciated!

Attachment 97774

The log

Attachment 97775

Current tune

Again, any help is greatly appreciated. I thought it was in the DFCO, but if it is, I'm just missing something.

What does an air box mod do?

Is the MAF sensor still in the factory location and does the MAF sensor have a screen in front of it?

Quote:

---

Originally Posted by 5FDP

What does an air box mod do?

Is the MAF sensor still in the factory location and does the MAF sensor have a screen in front of it?

---

I opened the side facing inner fender and have it pulling air from there (more outside the engine bay.
No change to MAF or screen, stock breather tube to TB. (I've heard it is bad to remove screen on these, but some seem to feel it works better)
So, essentially I am just getting air from a larger opening from inner fender.

Quote:

---

Originally Posted by 5FDP

What does an air box mod do?

To answer more specifically, it is my idea of making a CIA from the factory air box. I cut out the side facing the inner fender, cut a hole in inner fender and seal the space with a memory foam type material so it pulls fresh are from a hole in the inner fender well

Is the MAF sensor still in the factory location and does the MAF sensor have a screen in front of it?

Other than the air box and the higher flowing air filter, everything is stock and in their original locations MAF is original and screen is in

---

Thanks much for the reply

Ok, those things alone shouldn't be the cause of this lean condition.

I guess I would just double check all your hose connections around the MAF and throttle body to make sure you don't have a leak. Check the tubing for cracks in the rubber/plastic and look over the PCV hose.

A bone stock tune shouldn't be spitting out those codes unless there is a problem on hand. Be it a vacuum leak or an extreme drop in fuel pressure.

Quote:

---

Originally Posted by 5FDP

Ok, those things alone shouldn't be the cause of this lean condition.

I guess I would just double check all your hose connections around the MAF and throttle body to make sure you don't have a leak. Check the tubing for cracks in the rubber/plastic and look over the PCV hose.

A bone stock tune shouldn't be spitting out those codes unless there is a problem on hand. Be it a vacuum leak or an extreme drop in fuel pressure.

---

The log doesn't show huge pressure drops, if it's accurate, but I'll revisit the log again.

I had a DTC when I first put the air box back together, the filter slipped off, but I forget what the code was, however, that air filter is finicky, it can slip off if too tight or the box isn't put in just right, which it did slip off on me the first time, which caused that code I don't remember.
Everything on the top side is fine, but I'll look to see if that filter popped off again. That would be the only leak I could think of, but I will also check everything else again as well.
Do you think the filter popping off the tube could cause this lean condition?

Thanks for the input

Quote:

---

Originally Posted by 5FDP

Ok, those things alone shouldn't be the cause of this lean condition.

I guess I would just double check all your hose connections around the MAF and throttle body to make sure you don't have a leak. Check the tubing for cracks in the rubber/plastic and look over the PCV hose.

A bone stock tune shouldn't be spitting out those codes unless there is a problem on hand. Be it a vacuum leak or an extreme drop in fuel pressure.

---

You mention a "bone stock tune", just so you know, I have modified the tune on the truck (the on I posted above) is the on I currently have in it, and the problem came after I wrote this particular tune. So, if this might make a difference, then I have a situation, because everything is sealed up nice and tight. There are no leaks or anything out of place I can see.
Oh, the only other thing I did was use NGK6 plugs when I changed them.

So currently I am at a loss.

Any other ideas? Could you look at my adjusted tune maybe and see if anything looks really out of place? Please and thanks!

Well, I got it fixed, I am pretty sure.
It was definitely something in the tune I attached above. I went back to my best tune #3 (at the time) and made a few adjustments to get my lower end and take off more peppy as I wanted and although the fuel trims bounce around a little, no lean condition and and no codes.
The codes below were what were pulled if this is any indication of the tune issue. I don't know for sure what part of the tune caused the lean condition and codes, I would love to adjust the tune above as it was (just before I messed with something I shouldn't have or did it backwards) was a really good feeling tune.

Attachment 97811

No exhaust or cat removal?

Quote:

---

Originally Posted by ttz06vette

No exhaust or cat removal?

---

No, as stated in a previous note above, just the cooler plugs and I opened the air box to make my own CIA. Bone stock truck otherwise.
I do intend to do an exhaust for sure, just not sure which one, but likely duals with the resonator part of the Borla kit as the mufflers near the rear bumper. I might do headers, but I will us the large downpipe and high flow cats either way.
I tossed around a throttle body, but was told the size I have is decent and if I go large, would likely have to update MAF. I'm still researching and learning, but the goal is just get every little bit out of what I have and end up with. Easy bolt on stuff that will help if it is worth the money for return is never out of the equation, but I doubt I'll go any power adders at this time. I just want her to be a neat fun daily (good weather) driver that will go in the bad stuff should I get caught out.
The ONLY other possibility is a trans upgrade, but even that is something everyone seems to vary on in opinions. The right 6 speed would certainly improve mileage, but I am up a bit just from this tune, I haven't checked straight highway yet, but my average "by the gauge" has risen even with me doing logging with hard pulls.

As for a DD, there is a Subay in the works I think, I'd rather go GMC, but the Acadia and Terrain don't have the best reliability ratings and the Subay is better off road and in reliability.

I have my Regal GS that I kept after it was wrecked, it's a well tuned barely modded 3800 S/C motor so as for a real toy, likely that motor, built and put in a S-10, maybe a Jeep (they are so pricey tho) or even a Fiero if I can land a decent 1988 model Formula or GT (formula preferred for a couple reasons).

So there's my life in a 3 minute read.... LOL

You got any ideas, please share, some of the parts of the tune are from a 07 Corvette just FYI. I could share the current tune that seemed to fix the issue (well mostly I hope) and you could compare them. I'm far from a master tuner, but I research, read, research more, watch videos and feel I have learned pretty good, but I still can't seem to get some answers on this TBSS and the TCC and STBLA Track controllers, enabled/disabled, how do they, OR do they affect my tune and is there a way to have them use an adjusted tune like I was able to do with my Regal and the sport mode transmission button setting. Any ideas on where I may find info on this is appreciated as well, the posts here don't seem to get answered about those items.

Thanks for the reply

I got the same error codes when I removed my cats until I richened up the MAF curve that’s why I asked.

Quote:

---

Originally Posted by ttz06vette

I got the same error codes when I removed my cats until I richened up the MAF curve that’s why I asked.

---

I'm still learning the MAF curve settings. I think one of the tunes I was looking at and using some info from may have had the MAF removed and my truck didn't like those tables.
I went back to almost stock settings and relieved the lean issue (mostly), but I'm not quite good enough in that understanding to attempt any readjusting.
I haven't looked through a couple of the last really long logs, but from what I saw on the tablet, I may be a little on the rich side now mostly. Better than lean, but not better for MPG

OK, so I would really love a little help here please and thanks.
This is a good feeling tune, and a log to go with
The only thing is that I am still just a tad lean in some areas and I'd love it to get more 0'd but I can't seem to find the proper adjustment to get it there.
Attachment 97867
Attachment 97868
Something in this tune could use a tweak to lessen the lean condition I am seeing at low speeds/rpms, but for the life of me, I can't quite find the area that may be hurting me.

Any thoughts/suggestions are so appreciated. I have it so close to "what I feel" feels the best, but if LTFT numbers >0 are lean as I understand it, then I need an adjustment.

Use your data logs to tell you where.

If you make a graph/chart that matches the airflow tables in the editor, it will show you exactly where it's lean or rich on the airflow table. Then you can take that information to add or remove fuel. Like if between 1,800 and 2,500hz on the MAF curve it's lean, then you could add fuel to that portion to see if it stops being lean.

You will drive yourself crazy if you want perfection, that just won't happen. If fuel trims are withing 3-5% of zero, that is good enough and the computer is more than able to adjust the fueling on the fly to correct it.

Quote:

---

Originally Posted by 5FDP

Use your data logs to tell you where.

If you make a graph/chart that matches the airflow tables in the editor, it will show you exactly where it's lean or rich on the airflow table. Then you can take that information to add or remove fuel. Like if between 1,800 and 2,500hz on the MAF curve it's lean, then you could add fuel to that portion to see if it stops being lean.

You will drive yourself crazy if you want perfection, that just won't happen. If fuel trims are withing 3-5% of zero, that is good enough and the computer is more than able to adjust the fueling on the fly to correct it.

---

I have been told this as per the 3-5%, I am just seeing some 5 to 8's and would like to tone them down. I can tell by the log when/where it happens, it's basically at low "cruising type" rpm's Say 20 to 30% throttle in the 1200 to 1500 rpm range. It's fine at idle, it's fine with just a slight throttle bump at those locations, but staying steady speeds and rpm's mentioned it bounces in the 6 to 8 range. I've seen it hit a 9 and 10 then just a bump from 3o to 33% throttle 0's it out.
I get down at that 1300 rpm range, at about 40mph and about 25% throttle and it will hit 9 and 10 for just a moment then settles back around 6 to 8. Everywhere else it looks pretty good, I can deal with 1 to 3, maybe even a 5 spotted here and there, but 9 to 10 seems thin.

So here is my problem, since I feel I know where/when it is happening, I'm not exactly sure how to adjust it or exactly even where when you get to that fine tune requirement. You mentioned a graph/chart, I'm not sure how to do this, and I don't seem to see anything that shows a MAF curve with anything in hz except the Engine>Airflow>General>MAF Calibration> Airflow vs. Freq. Low/High.

The MAF airflow vs freq is what I am referring too.

Read the VCM scanner section stickys, they will show you in a general way how to make graphs or charts to log this data. Youtube some of this stuff, there are TONS of video's out there that should help someone. All you are doing it taking what is in the editor and making it in the scanner so you can watch what it is doing.