25% is BS.... From what I know the average should be under 10%.

I would be looking at and logging O2 sensors, KR, Ignition, STFT, LTFT etc...

 

I did a couple hours of data logging last night. O2 is switching, no big knock events, timing is normal during WOT. 8 pulls out of 10 feel like a slug, 2 feel normal. I dropped the car off this morning for an unrelated issue, and the Service Advisor looked at me like I grew a second head, that was speaking Greek, when I told him the LTFT was excessive... So we'll see how that plays out.

 

Got the call from the dealer, can not duplicate.

 

Show them the data logs.

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Yeah, I can't get out there today. I have another appointment next week for delamination of the windshield and rear view mirror. I'll argue it out then. It's pointless to try to argue about this with a service advisor that doesn't understand what a fuel trim even is. I'm very hopeful that they've fixed the loud banging noise from the rear that I had posted videos about before. As long as that's fixed, I'll consider this trip a win. One thing at a time, right? Here's that video.

https://youtu.be/u3wEIDicjIE

 

Hey @ChicagoTommy
Did they sort this out? If so what was that?

 

Hey,

I'm a bit lost with understanding this so please advice ...

My LTFT goes to about 20+ in idle. It goes down on higher RPM.
But STFT never exceed 2.5+ so why the LTFT goes so high? I thought LTFT is an avarage of STFT?
No check engine yet. But scan tool show P1101 pending code.
MAF in the idle shows about 2.5 g/s After disconnecting MAF the measure dropped to 18+
I checked around for air leak and all seems to be OK.
What else should I check?

I did those test in my garage with gate half open. I doubt it could be caused by bad air circulation?

 

LTFT is not necessarily an average of STFT, it is a long term correction for AFR. LTFT is a compensation for changes in internal and external conditions. Pumping losses due to engine wear, or due to increase in altitude,etc.

STFT sees those changes first, then LTFT takes over, adjusts and stores those compensations in memory.

Good luck. I'll try to see if this is a common issue and get back to you.


Also, how did you go about resetting the the fuel trims?

 

What kinda fuel are you using

 

My long-term fuel trim is always, and I mean always averaging between 10 and 11. It's either normal for this engine, or there is just a very small unregulated leaked into my intake manifold that I can just can't find.

I gave up trying to find it. Just no appreciable difference in performance or fuel mileage.



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Having same problem on my 2014 ATS 2.0L, I have spent 3 months and nearly $2k trying to fix it. Initially STFT would just max out at like 35%+ at idle, found a vac line hanging loose under the car and a couple vac lines behind the base of the radiator that had been chewed up, fixed those issues but still vac leak somewhere. Took it to a dealer, they found more lines chewed so I had the entire vac line assembly replaced.

I have also replaced MAF and MAP sensors and new PCV valves and new PCV lines [was relatively inexpensive and was hoping to find the solution] and have sprayed carb cleaner everywhere looking for a leak somewhere else.

Data logged a couple days ago and STFT has stabilized and LTFT is now 17-22%+ at idle, I put a new throttle body on Dec or Jan and just used the old TB Gasket cause it looked fine, but went ahead and ordered a new gasket this week and will replace that. O2 sensors seem to be reading fine, don't think their is an issue there.

It has been to the dealer twice and they seem to think the car is fine, in their opinion fuel trims are no longer throwing a lean code so they claim it is fixed. I am getting close to just throwing my hands up. Best of luck to you on finding the problem.

 

That's on a stock tune?!

 

No, I have a few bolt-ons and a tune.

 

I see the throttle body is upgraded and you're going to change the gasket. Did you happen to check the charge pipe that is connected to it? I'm not sure if you got the adapter or FMIC Kit, but check by the MAP connection. Maybe the screw fell out that blocks the boost gauge attachment port (if your adapter or charge pipe offered that addition).

 

Thanks for the tips. I have the FMIC too and all the hose connections have been checked multiple times at this point, lol. Good tip on the boost gauge port, I hadn't thought of that and will double check it while I am replacing the TB gasket.

 

Only other thing I could think of lol. It sucks too because it's on the opposite side and facing the engine on my setup.

 

我也遇到了同样的问题。我不知道您用来解决这个问题的方法。我的LTFI高达25％-30％。我头疼，一直在寻找问题的根源。

 

I also encountered the same problem. I don't know the method you used to solve this problem. My LTFI is as high as 25%-30%. I have a headache and have been looking for the source of the problem.

 

I had the same thing, +25-35 LTFT. I replaced the upstream O2 sensor, not change. I inspected everything for leaks, could find any. I cleaned every sensor I could find, no change. Finally paid the dealer to do the diagnostic. For me it was a faulty MAF. I declined repair and replaced it myself (I think I paid around $40 for the sensor). LTFT usually around +5 now.