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Discussion Starter #1 (Edited)
I'm having trouble with a lean idle that only occurs right after coming to a stop. AFR goes up to to 18 or so, then after about 10 seconds AFR comes back down to stoich. This lean condition has caused to car to stall a couple times after coming to a stop. Besides that, idle and cruise are good with AFR in 14-15 range and trims less than +/- 3%. This issue seems to be significantly worse when the engine is below operating temp. It still occurs when the engine is warmed up, but AFRs do not go quite as lean and it takes less time to get back to stoich.

Car is an X SE and mods include just basic bolt ons. Specifically, fuel mods include ASNU 1100cc injectors and a DW65C pump. Issue started occurring after installing the injectors. I thought it was something that would subside once the injectors were dialed in, but now they are and the issue still continues.

No CEL's have come up. Ive already checked for exhaust leaks, vacuum leaks, and boost leaks and found nothing. I do not have a fuel pressure gauge, so I do not know my fuel pressure.

See attached logs. In the first log, issue occurs after line 220 or so. In the second log, after line 250. AFR is column M ("AFRADC")

Thank you for your help
 

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Why does your current fuel trim never switch to fuel trim low value -- did your tuner lower with your mid-low crossover values in the "Closed Loop - LT Trim Control" table?
 

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Interesting. These threads have been popping up more frequently. Mine does it when the car is warm. These I have also checked for vacuum, exhaust, and boost leaks but can't seem to find anything. I'm assuming it is either a bad front o2 sensor/ exhaust manifold gasket leak, or the MAF. If you find the cure please let us know!
 

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Why does your current fuel trim never switch to fuel trim low value -- did your tuner lower with your mid-low crossover values in the "Closed Loop - LT Trim Control" table?
Curious to know this also. I'll bet that LTFT-low jumps up quite a bit if this is fixed.
 

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Do you mind posting a log of about 5-10 minutes of normal street driving? Drive normal in stop and go traffic. Good to see what normal driving looks like. You may have to zip the csv file to make it fit for posting.
 

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Discussion Starter #10
Thanks for the replies.
I have cleaned the MAF and switched out FP relays and no change. I believe the only mechanical things it might be is a small pre front o2 sensor exhaust leak or a bad front 02 sensor. I doubt its the front 02 because my idle its still okay after the lean condition passes.

Why does your current fuel trim never switch to fuel trim low value -- did your tuner lower with your mid-low crossover values in the "Closed Loop - LT Trim Control" table?
Curious to know this also. I'll bet that LTFT-low jumps up quite a bit if this is fixed.
Strange, I never noticed this. Mid->Low and Low->Mid values are untouched (OEM values 62.5, 56.25 Hz). Just mid->high and high->mid have been lowered. ECU should see that maf hz and be storing low trim right?

Do you mind posting a log of about 5-10 minutes of normal street driving? Drive normal in stop and go traffic. Good to see what normal driving looks like. You may have to zip the csv file to make it fit for posting.
Attached a long driving log to OP.
The lean idle occurs at lines (1126-1204), (3016-3117), and (5578-5720).
 

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Not sure exactly how this came about, but your LTFT current ignores LTFT low until your car warms up past 180 deg F. Do you have the old ROM (from before you added the injectors) to do a diff? You can also PM me your ROMs if you like.
 

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My car does the same, amongst other weird idle issues. It is inconsistent and I have not been able to figure out the issue as well.

Today, it was 37 outside. I let the car warm up about 10-15 mins in my driveway. Drove the car all the way to work without an issue. As soon as I get to work (and am backing up in the parking lot), the car starts going lean. This is when I have already let off the gas and am in neutral and in the parking spot.

I tapped on the gas. And I barely tapped the gas. The rpms shot up to 2k and stayed there a couple seconds. They then dropped to under 1k (my idle is suppose to be at 1k). The AFR's leaned out again. Eventually they climbed up to 14.7. I shut off the car and walked away in disgust.

Please update if anyone figures out the cause of this issue.
 

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My car does the same, amongst other weird idle issues. It is inconsistent and I have not been able to figure out the issue as well.

Today, it was 37 outside. I let the car warm up about 10-15 mins in my driveway. Drove the car all the way to work without an issue. As soon as I get to work (and am backing up in the parking lot), the car starts going lean. This is when I have already let off the gas and am in neutral and in the parking spot.

I tapped on the gas. And I barely tapped the gas. The rpms shot up to 2k and stayed there a couple seconds. They then dropped to under 1k (my idle is suppose to be at 1k). The AFR's leaned out again. Eventually they climbed up to 14.7. I shut off the car and walked away in disgust.

Please update if anyone figures out the cause of this issue.
Post a log, please.
 

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Discussion Starter #15
Not sure exactly how this came about, but your LTFT current ignores LTFT low until your car warms up past 180 deg F. Do you have the old ROM (from before you added the injectors) to do a diff? You can also PM me your ROMs if you like.
That's right forgot about this. I think there is also a maximum intake temp and baro pressure range that must be met in order for fuel trim learning. That log must have been taken shortly after firing the car up.

I do not have an old ROM. I ran stock ROM before installing the new injectors.
 

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Discussion Starter #16
Interesting. These threads have been popping up more frequently. Mine does it when the car is warm. These I have also checked for vacuum, exhaust, and boost leaks but can't seem to find anything. I'm assuming it is either a bad front o2 sensor/ exhaust manifold gasket leak, or the MAF. If you find the cure please let us know!
I have a 09 ralliart. I had the same issue happen to me last week and again this week. I have no clue either but I hope someone knows

Sent from AutoGuide.com Free App
Mine does it too. Curious the fix for it.
My car does the same, amongst other weird idle issues. It is inconsistent and I have not been able to figure out the issue as well.

Today, it was 37 outside. I let the car warm up about 10-15 mins in my driveway. Drove the car all the way to work without an issue. As soon as I get to work (and am backing up in the parking lot), the car starts going lean. This is when I have already let off the gas and am in neutral and in the parking spot.

I tapped on the gas. And I barely tapped the gas. The rpms shot up to 2k and stayed there a couple seconds. They then dropped to under 1k (my idle is suppose to be at 1k). The AFR's leaned out again. Eventually they climbed up to 14.7. I shut off the car and walked away in disgust.

Please update if anyone figures out the cause of this issue.
What mods do you guys have? Specifically what injectors? Also what car, MR or GSR?

Lets find some similarities.



I'm beginning to think its an injector latency issue. Seems like the injectors are slow to respond after deceleration to provide sufficient fuel for idle. Also, I am bogging down pretty bad when taking off from a stop. Its been pretty dangerous at times trying to make quick left turn across traffic. And also downshifts seem delayed. There is a noticeably longer time from when I pull the paddle to when the revs shoot up. All of these seem consistent with a latency issue.
 

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What mods do you guys have? Specifically what injectors? Also what car, MR or GSR?

Lets find some similarities.



I'm beginning to think its an injector latency issue. Seems like the injectors are slow to respond after deceleration to provide sufficient fuel for idle. Also, I am bogging down pretty bad when taking off from a stop. Its been pretty dangerous at times trying to make quick left turn across traffic. And also downshifts seem delayed. There is a noticeably longer time from when I pull the paddle to when the revs shoot up. All of these seem consistent with a latency issue.
My injectors are FIC1100. It's a 2013 GSR with 6k miles and modded at 3k. The rest of the mods are as followed:

ETS Intake
3.5" ETS FMIC
ETS UICP
Turbo XS TBE
3port
DW65C

Dual tuned for E85 and 93. Been running on the E85 though
 

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This will seem very counterintuitive, but excessively high idle fuel pressure will result in a lean run condition. Most high impedance injectors lose flow at idle pulsewidths when they are run at 4+ bar pressure. Search for threads covering enlarging the fuel return orifice (I usually do 2 mm) and checking to see if the return line is clogged.
 

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This will seem very counterintuitive, but excessively high idle fuel pressure will result in a lean run condition. Most high impedance injectors lose flow at idle pulsewidths when they are run at 4+ bar pressure. Search for threads covering enlarging the fuel return orifice (I usually do 2 mm) and checking to see if the return line is clogged.
Would that also cause symptoms as seen in these videos?

http://www.evoxforums.com/forums/showthread.php?t=187594
 

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Have the same problem
2011 gsr 21k miles
injen intake,ets hfc and v2 quiet and map upper ic pipe.
running a modified (for the intake) ots tune currently. other than that its all stock
 
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