What could possibly cause 14.2 AFR @ Idle

[boostdmazda3]

^^ i think its fine mine is usually in the 14.4-14.6 range at idle. If it was holding at 14.0-14.2 at idle i would be worried.

[x09MS3GT]

Originally Posted by boostdmazda3 ^^ i think its fine mine is usually in the 14.4-14.6 range at idle. If it was holding at 14.0-14.2 at idle i would be worried.

Kinda figured as much, just wanted the comfort of knowing for sure. Thanks.

[MPS_Fan]

Mine is nailed at 14.6-14.8. If you have 14.4, your STFT should be extremely negative.

[infeKteDx]

Hoping someone can help me out here...

Threw a P0171 - System Too Lean randomly about three weeks ago, at a light.

STFT's climb to 25% while I'm idling.

I checked for a boost / vac leak, found nothing, took it to a shop, they said the clamp on TIP to turbo was loose, tightened it...still same issue.

If I push it, AFR's hit 9.5, (Only pushed it that ONE time for a log) ...

Shop says it's probably my primary o2 sensor, they have given me the option to replace it...I have no idea what to do at this point.

The log below shows STFT hitting -21 randomly while driving, and the 9.5 AFR...I do not have a lot of the +25% STFT while Idling, but I promise you it does it. When driving my STFT's seem to be within -/+ 5%, but whenever I let go of the gas peddle, it's all over the place, -18/+24, -16/+25....random stuff like that.

Does anyone have any ideas, im completely at a loss of what to do...

EDIT: I have also already updated AP, reset ECU, and reinstalled my tune. I was driving perfectly fine for the last YEAR, without issue, then this randomly happened.

[smoogs12]

@infeKteDx; do you yave anyone local that you can swap out o2 sensors with?

Tapa

[infeKteDx]

I don't think so, I don't really know any guys in the area :/

[smoogs12]

PA has a huge nator group. Get involved man!

Anyways, if you can gain access to a propane torch and introduce a bit of propane to the intake stream you should be able to reasonably conclude weather or not you have a sensor malfunction or a real lean condition.

When you introduce the propane just watch the stft. If you are really running lean then they should go way negative. If its a sensor malfunction then you will see no change in idle trims.

[infeKteDx]

Originally Posted by smoogs12 PA has a huge nator group. Get involved man! Anyways, if you can gain access to a propane torch and introduce a bit of propane to the intake stream you should be able to reasonably conclude weather or not you have a sensor malfunction or a real lean condition. When you introduce the propane just watch the stft. If you are really running lean then they should go way negative. If its a sensor malfunction then you will see no change in idle trims.

I'm not entirely sure how I'd even do that...

The shitty thing is, the car is sitting at a subaru shop in MD, called Agile Performance, and they're awesome with cars...I was hoping they could pin point the issue, but apparently not...

Apparently idling around 14 AFR is normal for these cars? He was telling me that it's gotta be the o2 sensor since the car is idling around 14 AFR...

[smoogs12]

Originally Posted by infeKteDx I'm not entirely sure how I'd even do that... The shitty thing is, the car is sitting at a subaru shop in MD, called Agile Performance, and they're awesome with cars...I was hoping they could pin point the issue, but apparently not... Apparently idling around 14 AFR is normal for these cars? He was telling me that it's gotta be the o2 sensor since the car is idling around 14 AFR...

What do you mean "not sure how you'd do it"?

And yes usually the lean code is a sensor malfunction.

Also a 14 afr is not normal. should idle @ 14.6-14.8

[infeKteDx]

Originally Posted by smoogs12 What do you mean "not sure how you'd do it"? And yes usually the lean code is a sensor malfunction. Also a 14 afr is not normal. should idle @ 14.6-14.8

I meant 14.7, sorry...

And I mean, how do I introduce propane into the intake? ...I take the filter off? ...or I just sit it by the intake filter ...I've never done anything like that before, sorry.

[smoogs12]

Yes just let the propane flow into the filter (dont take off the filter).

Doesn't have to be a huge amount of propane either.

[ChimmyChong]

You recently put on that eBay dp? Did you weld in a new 2nd sensor o2 bung?

[infeKteDx]

Originally Posted by ChimmyChong You recently put on that eBay dp? Did you weld in a new 2nd sensor o2 bung?

Nope, it has been on for about a year, I've been tuned with all my parts for a year with no issues at all...I pull off the highway 3 weeks ago, stop at a light, and ding! The check engine light comes on...STFT's 25% at idle for whatever reason...

[x09MS3GT]

Originally Posted by infeKteDx Nope, it has been on for about a year, I've been tuned with all my parts for a year with no issues at all...I pull off the highway 3 weeks ago, stop at a light, and ding! The check engine light comes on...STFT's 25% at idle for whatever reason...

I have this same exact problem man.

Damn car out of the blue decided to start up one day, and idle at 12.0 AFR. STFT was pegged at -25 %. I babied the car home. Pissed as fuck.

tore the entire top of the car apart checking for boost leaks, cracked hoses, vacuum lines etc etc. Cleaned the MAF as well. Nothing man.

I re-flashed my tune and it seemed the problem went away. Or so i thought. 20 miles later it came back. But not as extreme this time. Now , the AFR was bad in all ranges. Crusing the damn thing would sit at 14.0 , and climb up and down to 15.5 down to 14.0 , over and over and over, like 4 or 5 times in a second or 2. Car is running like complete shit. I wont even go past 1/4 pedal input.

I have a new O2 on order right now from Rockauto.com

NTK # 24357 Wideband OEM O2 sensor.

Waiting for it to get here.

[BrandonRKD]

Originally Posted by x09MS3GT I have this same exact problem man. Damn car out of the blue decided to start up one day, and idle at 12.0 AFR. STFT was pegged at -25 %. I babied the car home. Pissed as fuck. tore the entire top of the car apart checking for boost leaks, cracked hoses, vacuum lines etc etc. Cleaned the MAF as well. Nothing man. I re-flashed my tune and it seemed the problem went away. Or so i thought. 20 miles later it came back. But not as extreme this time. Now , the AFR was bad in all ranges. Crusing the damn thing would sit at 14.0 , and climb up and down to 15.5 down to 14.0 , over and over and over, like 4 or 5 times in a second or 2. Car is running like complete shit. I wont even go past 1/4 pedal input. I have a new O2 on order right now from Rockauto.com NTK # 24357 Wideband OEM O2 sensor. Waiting for it to get here.

Did the O2 fix the problem?

I Tapped that

[x09MS3GT]

I replaced the O2 sensor, and reflashed the tune. Problem never came back.
Can't really determine what was wrong with it in the first place. Wierd problem that came out of nowhere.

As far as the wierd AFR @ idle and crusing problem, IIRC there is a fix to the Shift control folder in ATR.
The Load Based Fuel Compensation Tables.

Rich AFR when cruising 14.41 to 14.55 cant find why!

Read that, it should fix your problem.

Good luck.