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Discussion Starter #1
My car is running rich at idle when I monitor the fuel trims by obd. I don't seem to know what's causing it .


Check below sensors and their integrity and they are doing fine .

1. 02 sensor
2. Maf sensor
3. Coolant sensor (recently replaced)

Any idea where I should look ?

Thanks

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09 Altima 3.5SE 6MT Sedan
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Leaky injector(s) would cause this. Does OBDII report the correct ambient temp...if it's reporting -40'F then this would cause problems too.

How rich are we talking? What %'s are the LTFT and STFT at?
 

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Discussion Starter #3
Leaky injector(s) would cause this. Does OBDII report the correct ambient temp...if it's reporting -40'F then this would cause problems too.

How rich are we talking? What %'s are the LTFT and STFT at?
Injectors are good
Ambient reporting correctly
Ltft ≤3
Stft -7 ≤ -25 (Is changes fast, but it's a little bit stable when the car idles)

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09 Altima 3.5SE 6MT Sedan
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Ok, and how does the B1S1 sensor output look while this is going on? Can you graph both, say with Torque or similar?
 

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Like being hinted at, the O2 sensor will NOT be reading correctly with that much fuel being subtracted.

I for one want proof of the injector check, this poster has misinformed us before. Like now.
 

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Discussion Starter #7
Like being hinted at, the O2 sensor will NOT be reading correctly with that much fuel being subtracted.

I for one want proof of the injector check, this poster has misinformed us before. Like now.
How do I misinform anyone trying to help help me with my car problem, don't you think it's otherwise?
Am not that experience as you guys are in the automobile world you know; so misinformation and related can come up. Don't cut my neck off for this please.
Thanks

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Discussion Starter #8
Ok, and how does the B1S1 sensor output look while this is going on? Can you graph both, say with Torque or similar?
I can graph four parameters/sensors of the car as it's running with the obd software I have.
What parameters do you want to see for the graphing ? Up to 4.
Thanks

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09 Altima 3.5SE 6MT Sedan
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Why not graph rpm, b1s1 02, stft, and maybe b1s2?
 

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The O2S1 is all you need. Still waiting on the injectors being good proof. Misled like I said. If rich the O2 will NOT be normal.

You already have once claimed this problem is fixed..........


????????
 

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Discussion Starter #12
The O2S1 is all you need. Still waiting on the injectors being good proof. Misled like I said. If rich the O2 will NOT be normal.

You already have once claimed this problem is fixed..........


????????
Yes exactly
But afterwards started to have running rich at idle but not overall fuel trims. Besides this trims am having is way better than what I was having earlier, it was staying at ≤ -10 ltft all the time; now it's ≤ 3. Just that am running rich at idle which can be seen in stft but is not enough to change the ltft at a drive cycle. Irrespective, that's a fix because I was having VERY bad gas mileage earlier.
Hope you understand it now
Read it somewhere that after running rich for a while (1.5 years with mine) and fixing it you have to change the engine oil because it's contaminated with fuel and can still make you run rich; you guys think that's a fact?

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It can be a fact in 15 minutes if rich enough. The fuel vapor then sucks through PCV to richen the mixture. The O2 is supposed to correct for it though unless it is dead, and too much fuel does that as well as killing the converter. The engine wears like lightning too as the oil is cut by fuel to let engine wear far more. You may drain out 8 quarts and all of the extra is fuel.
 

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Discussion Starter #14
It can be a fact in 15 minutes if rich enough. The fuel vapor then sucks through PCV to richen the mixture. The O2 is supposed to correct for it though unless it is dead, and too much fuel does that as well as killing the converter. The engine wears like lightning too as the oil is cut by fuel to let engine wear far more. You may drain out 8 quarts and all of the extra is fuel.
Noted
But will graph the sensor parameters adviced and share so we can nail the problem down.
With the convertor I don't think it's in bad shape because I pass emissions now but not earlier when I was running super rich.

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You are not running nearly so rich as you claim if you have a converter and it has not gone bad yet after 1.5 years. (!!!!!!!!) The 15 minutes can easily apply to that as well. Running rich at idle can kill a cat in 5 minutes.

I still see there is absolutely no mention of your injector checking method and no proof. You can run around in your circles of misinformation all you want.
 

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Discussion Starter #16
You are not running nearly so rich as you claim if you have a converter and it has not gone bad yet after 1.5 years. (!!!!!!!!) The 15 minutes can easily apply to that as well. Running rich at idle can kill a cat in 5 minutes.

I still see there is absolutely no mention of your injector checking method and no proof. You can run around in your circles of misinformation all you want.
Well
As any angle you want to see it that's how it is. With the injector; again it doesn't have any problem, not dripping fuel or related. With this B16 cars dismantling engine assembly to get injectors is a pain in the ass, nevertheless have done that check with a mechanic before and it wasn't dripping fuel KOEO. Please get this on the injector.
Yes it pass emissions
Can you explain to me what's this 15min rule is all about ?
And the car is not running super rich, please read this OP again, it's run rich at idle; even with that it's intermittent. Not when the car is cruising.
Will be taking the car for a spin today so will share the graphing and the emissions passage screenshot as well.
Trust that will help all of us

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Discussion Starter #17
Hello
Please find the attached link for the video as per requested for the sensors. Maximise the the YouTube window to see all the sensors well.




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09 Altima 3.5SE 6MT Sedan
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What's going on at this point? Weird spikes in rpms lead to changes in STFT. Is it possible you have an rpm sensor issue?

100785
 

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Discussion Starter #19 (Edited)
What's going on at this point? Weird spikes in rpms lead to changes in STFT. Is it possible you have an rpm sensor issue?

View attachment 100785
So with this the 02 sensor is working well?
Should we probe around the rpms? Is it a sensor or something. There is no code related to the rpms, the only codes (P0840, P0845) I have presently which I have ordered for parts are transmission fluid pressure sensor A & B that has gone bad.
You know these cars don't have manual idling adjuster but electronic one controlled by the throttle body.
One thing I have noticed is sometimes when the rpms goes down < 560+ and <600 when idling the stft goes higher in negatives.
One last weird thing I have also noticed, the car fuel trims runs fine and in balance in the morning or early driving but changes after running hot or at it's temperature, it start to idles rough running rich at idle.

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Chiming in on the rpm irregularities, they are absolutely not right. When engine misses it goes rich as the fuel is unburned then. Ignition issue. The O2S1 matched to the rpm dropouts shows it. The S2 shows cat already is not in the best of shape, it is jumping around way too much.

If it passes emissions misfiring like that you have literally no emissions testing at all there, that amount should fail you instantly. Being better cold says a part is getting hot to fail, maybe a coil. Or two.
 
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