Front main o2 sensor lazy?

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This is on the Kia 2.4L, it’s the main front o2 sensor the $300 one that controls the a/f and all that.

And honestly this may not even be an issue it’s just something I observe and it might just be the nature of drive-by wire.
So the throttle response I think it’s very nice…. after adjusting the TPS sensor on the pedal, it’s precise, pretty instantaneous… no real delay, I don’t have a bad thing to say about it BUT…..

Let’s say I’m in third gear , and I pull from a off ramp up to Thruway speeds, There is a noticeable increase in power from 80% to wot. It literally feels like a switch… or Honda vtech 😂 And I’m just wondering if the front 02 sensor is getting lazy for the first 80% of the throttle and not reacting quick enough to throttle inputs, then when at wot it’s ignored? I don’t know this is just speculation and what it feels like the car is doing.

Gas mileage seems acceptable for the driving conditions. Every start up a one to two minute warm-up, well because I don’t need to say more.
Gas mileage can range from low 20s exercising the RPMs and shifting frequently, to high 30s on the highway with no AC.

I very rarely go wot, but when I do… I notice this.

So what do you guys think? Thanks.

EDIT: I do have an OBD computer with live data, graphs and other information that I could use to maybe read the readings of the sensors if I knew how to decipher the reading, so if someone could just give me a baseline on what data I should be looking at and what the numbers may be should be on average or what variations I should be looking for etc..
 
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Well, I really don't know without driving the car from when it was new and how it is today, just to see/feel the differences in power & torque output.

Some of the older Hyundai/KIA engines made good power & torque as you are saying but, WHERE in the RPM range is this power & torque? IDK!
It could be torque deficient down low while at the same time, making good high(er) RPM power...sorta in that HONDA V-Tech way.

It's nice to compare a Hyundai/KIA to a HONDA just for comparison sake but, you can't compare to a HONDA as those things are amazing in their own right. But, I think I know what you mean! (y)
 

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Well, I really don't know without driving the car from when it was new and how it is today, just to see/feel the differences in power & torque output.

Some of the older Hyundai/KIA engines made good power & torque as you are saying but, WHERE in the RPM range is this power & torque? IDK!
It could be torque deficient down low while at the same time, making good high(er) RPM power...sorta in that HONDA V-Tech way.

It's nice to compare a Hyundai/KIA to a HONDA just for comparison sake but, you can't compare to a HONDA as those things are amazing in their own right. But, I think I know what you mean! (y)
Power and torque is very nice it comes on strong down low and it holds all the way to the 6500 RPM redline.

And I meant that in the most positive light the Honda comment, that was not a diss or anything like that I respect Honda, and as most Honda owners experienced, vtech is a very real thing LOL

My Kia is not a Honda…. but that’s the sensation the throttle/engine gives from 80% to wide-open throttle

As I said I respect Honda, would never own one, not because they’re bad cars, quite the opposite, it’s just every third person has a Honda.
 
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1 SX

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Are you feeling the kick down switch doing it's job?
Honestly that’s why I posted this question because I’m not sure what I’m feeling. But yeah it feels like a switch and a definite increase in power. Even from 3000 RPMs upwards i can feel the difference from 80% to wide-open throttle.

Another analogy, it feels like when the AC is on and go to wide open throttle, that power increase when the AC compressor turns off to give you more power, that you can feel.

It’s noticeable but it’s not an end all and very livable if it’s part of the design, I kind of like it honestly but again I’m thinking about efficiency and gas mileage, and even down the catalytic converter health so if the sensors are getting weak or lazy that it would be wise to replace them…

I can only compare the 2.4 L engines that I’ve had in past and have in the sonata. The issue is the automatic doesn’t really let you do anything except maybe redline it. No control what’s so ever. The transmission logic is good don’t get me wrong but it’s not a manual, and the automatics even in manual mode will upshift and down shift for you so it’s not really useful in any sense of the imagination, and only for selecting second gear to go up snow hills.
 
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TCL

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I had a 2010 2.4 liter SX Forte, but an automatic. It had a definite kick down and it did shut the AC down when floored to give it more power. I bought it new and put 215,00 miles on it and it always did this.
If you are looking for 1 week old SX floor mats and brand new mud guards and rear Monroe shocks PM me.
 

1 SX

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I had a 2010 2.4 liter SX Forte, but an automatic. It had a definite kick down and it did shut the AC down when floored to give it more power. I bought it new and put 215,00 miles on it and it always did this.
If you are looking for 1 week old SX floor mats and brand new mud guards and rear Monroe shocks PM me.
I really agree with you, really I think is a design thing for EPA or something 😂 to eek out better gas mileage when you’re not at wide open throttle

Absolutely. I was actually looking for a second pair of floor mats so I could swap them out for the wet season, and mud guards? That actually might look good on this car lol. I’m sending you a PM thank you.
 
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Power and torque is very nice it comes on strong down low and it holds all the way to the 6500 RPM redline.

And I meant that in the most positive light the Honda comment, that was not a diss or anything like that I respect Honda, and as most Honda owners experienced, vtech is a very real thing LOL

My Kia is not a Honda…. but that’s the sensation the throttle/engine gives from 80% to wide-open throttle

As I said I respect Honda, would never own one, not because they’re bad cars, quite the opposite, it’s just every third person has a Honda.
To be certain, I know what you meant, all in a good way for sure! (y)
I didn't think that you were dissing Honda's and I wouldn't care if you did. :p
I've owned my share of Honda vehicles but I don't think for one minute that they're the be all/end all of mainstream vehicles.
I like very much Hyundai/KIA vehicles on many fronts. ATMOF, I've been having good success with NISSAN vehicles and maybe even better reliability with them personally compared to my past Honda/Toyota/Lexus vehicles, even though Nissan's reliability has tanked lately.
Others may laugh at me for liking NISSAN products but, it is what it is! 🤷‍♂️
 
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There is a noticeable increase in power from 80% to wot.
I think it's the transition from closed loop stoichiometric to open loop rich.
and the automatics even in manual mode will upshift and down shift for you so it’s not really useful in any sense of the imagination, and only for selecting second gear to go up snow hills.
I put my auto into manual mode whenever I use the cruise control, to avoid unneeded downshifting.
 
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I don't think WOT use O2 output to adjust the air fuel, more like just open loop calculation with air only, especially with drive by wire they would compensate artificially instead of waiting till it is too rich or too lean to feedback and adjust (and take away some safety margin to make the engine more efficient).
 
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I don't think WOT use O2 output to adjust the air fuel, more like just open loop calculation with air only

It uses the fuel trims learned during part-throttle operation during WOT, if it is in fact in open loop during WOT. I don't think engines with wideband O2 sensors go open loop during WOT.
 

1 SX

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UPDATE:

I think im just going to replace the front main o2 sensor. Ive read even on here that after 100K they start getting slow but won't throw check engine light... any truth to that? I can read values of o2 sensors, what numbers should I be looking for? In the factory service manual they give these specs:
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I will get the OEM o2 sensors - they are double the price of aftermarket but again I believe in using quality components and doing the job once.. Im thinking I will replace the main one and sensor 2 just because even OEM sensor 2 is 58 bucks.

I was really analyzing the way the throttle feels and sometimes less is more on acceleration/power.... for example if you're going up a mild hill at 40% throttle and let up on the throttle it actually kind of surges and gives you more power at 30% throttle but only after going to 40% or more.. I hope that makes sense..

there is no surging or anything though at 85% to WOT, like "something" is being ignored.
 

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I received both the main, and 2nd NTK O2 sensors. They are made in Japan, and look very well built. Will install this upcoming week.

IMG_1843.jpeg
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1 SX

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Update on this: I replaced both the front main o2, and bank 1 sensor 2. With the o2 sensor socket a pipe and some PB they both came out. NTK were the OEM sensors.

I'd say it feels substantially more "peppy" across the board on throttle inputs. I don't think it will translate into a "faster" car 0 to 60 type deal, but that "less is more" feeling in the throttle is a lot less. Gas mileage also increased a little under the same driving conditions... And the cat does not seem to "click" as much on cool down after a trip. (y)
 
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From what I understand, as the o2 sensors age, their response times slow down. Lazy is a word I've heard used. There are folks who understand this way better than I do.

Whenever my old Toyota Pickup develops an off-idle flat spot or surging feeling, I replace the front o2 sensor. Fortunately, that has never happened before 100,000 mile intervals on the o2 sensor. Newer sensors seem to last even longer. I have always stuck with OEM part number/brand sensors so far, with satisfactory results.
 
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Update on this: I replaced both the front main o2, and bank 1 sensor 2. With the o2 sensor socket a pipe and some PB they both came out. NTK were the OEM sensors.

I'd say it feels substantially more "peppy" across the board on throttle inputs. I don't think it will translate into a "faster" car 0 to 60 type deal, but that "less is more" feeling in the throttle is a lot less. Gas mileage also increased a little under the same driving conditions... And the cat does not seem to "click" as much on cool down after a trip. (y)
That front sensor wouldn't be "LAZY" since it's a wideband linear. It could still be contaminated though, and provide incorrect mixture assessment. I'm chiming in too late, but I would have been looking at the MAF first after verifying fuel pressure. But it's sensor replacement time anyhow, so not a waste.

Enjoy a '12 Forte is a very good car.
 

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That front sensor wouldn't be "LAZY" since it's a wideband linear. It could still be contaminated though, and provide incorrect mixture assessment. I'm chiming in too late, but I would have been looking at the MAF first after verifying fuel pressure. But it's sensor replacement time anyhow, so not a waste.

Enjoy a '12 Forte is a very good car.
thanks, im thinking it was contaminated also. All the little vents on the tip of o2 were almost completely shut off with a white carbon.. I did clean the MAP from what I remember. - it does not have a MAF sensor.

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for me this is treading on complex ground as you cannot see a hard fault.
I would get a diagnostic tool to analyse all the engine running parameters first
 
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