Help! Very high a/f learning

[xt2005bonbon]

You said 'new MAF'. So it is two years old then?

Another test you could do is check the MAF wiring and connection. I suffered from it before (although LTFT became negative, not positive). I checked it by having the car idle, hood opened, BtSsm running on my phone, twisting the MAF wires one way, then another way while watching for the fuel correct parameters on BtSsm. Mine changed right away when I was moving the cable a certain direction.. You could also hear the engine idle slightly change.

[xt2005bonbon]

It wouldn't, and it's absolutely idiotic for some to suggest such.

 

 

^Not very nice here.

 

 

 

He did not say his OTS was two years old until now. More details are always good. OTS tunes are not that good in general. You do need to adjust the tune for your specific engine.

[dwmccauley01]

So, in reality, the only AF correction which would be harmful is if the 40+ was making large corrections which will cause issues in Open Loop going too rich or lean possibly resulting in detonation. The range you are seeing correction will solely occur off when you are seeing little to no engine load. If you're hitting your AFRs up top I wouldn't really worry about it. If you're hitting 14.2ish at idle and 14.7 cruising you should be alright. I would probably just adjust your scaling as xt said. Its either that or smoke testing the your intake an exhaust to find a leak.

 

Edit: just read you already smoke tested. You should be fine

Edited January 20, 2021 by dwmccauley01

[zactek]

Thanks for all the replies guys. Even though it's my DD, I don't put on that many miles a year, so with about 9K in the last 2 years, I consider my MAF and O2 sensors fairly new,sorry for the confusion.

My AFR is where it should be across all the rpm and load ranges, and the LV is pretty steady,I was just worried about the idle range being so out of whack. No CEL's,drives great,idle is smooth.

Not sure if I can fully rely on a smoke test,so I'm gonna do the soapy water check around the IC/BOV/TGV connections and try the MAF wires wiggle test. All my hoses are silicone with new clamps and zip ties in the right places, so I'm gonna look in some not too usual areas. Can leaking PCV/ breather hoses cause a leak that would make it lean out at idle? I want to first rule out any leaks before I touch the tune,which has been good to me for the last 5 years

[DaveWaters]

I experience a similar issue. When I brought it to my tuners attention he told me that it’s heat soak causing this. Which makes sense at least in my case because what I’ve noticed is that if I drive for a while, when I stop and idle my LTFT is low like around 0 or .78 and will gradually rise to 14.84 the longer I sit and idle. I see this often at the drive thru. My wideband does show me hovering around 14.7 the whole time so it would appear that the ecu is making the needed short term corrections.

[xt2005bonbon]

Thanks for all the replies guys. Even though it's my DD, I don't put on that many miles a year, so with about 9K in the last 2 years, I consider my MAF and O2 sensors fairly new,sorry for the confusion.

My AFR is where it should be across all the rpm and load ranges, and the LV is pretty steady,I was just worried about the idle range being so out of whack. No CEL's,drives great,idle is smooth.

Not sure if I can fully rely on a smoke test,so I'm gonna do the soapy water check around the IC/BOV/TGV connections and try the MAF wires wiggle test. All my hoses are silicone with new clamps and zip ties in the right places, so I'm gonna look in some not too usual areas. Can leaking PCV/ breather hoses cause a leak that would make it lean out at idle? I want to first rule out any leaks before I touch the tune,which has been good to me for the last 5 years

 

I agree; you always want to touch the tune as a last resort after you know you have checked everything in terms of hardware and you are sure your sensors are in good shape. So, when exactly did the high LTFT idle begin to show up? Did it show since day 1 when you uploaded the OTS tune? Or did it show up later?

 

I experience a similar issue. When I brought it to my tuners attention he told me that it’s heat soak causing this. Which makes sense at least in my case because what I’ve noticed is that if I drive for a while, when I stop and idle my LTFT is low like around 0 or .78 and will gradually rise to 14.84 the longer I sit and idle. I see this often at the drive thru. My wideband does show me hovering around 14.7 the whole time so it would appear that the ecu is making the needed short term corrections.

 

IIRC, the tune has some kind of settings to adjust the fuel correction when intake temperatures begin to rise above a certain threshold. I need to recheck this though. Don't want to spread rumors

[solidxsnake]

The tune should certainly have temperature compensation built in to it. But remember that the IAT is by default at the MAF sensor, which is conceivably much cooler than the actual intake charge when idling in heatsoaked conditions, so temperature compensation for while you're actually moving likely won't correlate well to sitting still.

 

If you didn't have this issue previously on the same tune, I'd highly suspect a mechanical change. I know you said you smoke tested, but I'd double check for leaks. The symptoms you show certainly indicate to a minor vacuum leak.

[zactek]

Finally found my problem! An aftermarket crosspipe that was less than 4 years old. The flex section was completely rotted and letting in too much air only at idle,fooling the O2 sensor about a foot downstream. Bought a Grimmspeed one and installed, no more high A/F learning at idle and low load! No more lean code as well, hope this helps someone!

 

Zack K.

[ttnio]

smoke test for the above find?

[xt2005bonbon]

Finally found my problem! An aftermarket crosspipe that was less than 4 years old. The flex section was completely rotted and letting in too much air only at idle,fooling the O2 sensor about a foot downstream. Bought a Grimmspeed one and installed, no more high A/F learning at idle and low load! No more lean code as well, hope this helps someone!

 

Zack K.

 

 

First time I hear this. Good job finding this issue!

[zactek]

First time I hear this. Good job finding this issue!

 

First time for me as well, I did the whole exhaust when I first got the car and thought it would be bulletproof for a while. I did a smoke test on the intake,not the exhaust,and found nothing. I thought the car sounded a little louder lately,lol.

 

Zack K.