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Discussion Starter #1
I've been here before but lost my info so I'm starting new now.

I've been reading around and can't seem to put my finger on the issue here. I'll try to be as descriptive as possible.

99 Sephia, 126k miles, well taken care of.

Recent Work:
Replaced Valve Cover Gasket, Plugs & PCV Valve at 80k
Replaced Fuel Filter around 110k
Replaced Timing Belt, Water Pump & Pulleys, Ignition Coil Packs & Wires at 90k
Brakes at 120k (Front & Rear)

Current Issue.

The car drove fine till it started to sputter a bit then just stahl out. It sounded like it wasn't breathing right. I found the air intake hose (From the Air Filter Box to the Throttle Body) was cracked but was previously taped. I re-applied tape and car seemed ok for a hot minute then the same thing. I got it to run enough to get me to the store to read the code, bad MAF sensor. That was replaced and all was good for about a week.

Week 2. The engine light came on but the car seemed to still be running fine. I had the code read and got a P0171 Bank 1 System too lean. 1st common cause was a faulty MAF, so I swapped it out, reset the computer (Unplug battery for 5 min) and the light stayed off for a few days.

Week 3. Light came back on. I checked the MAF connections, cleaned them & applied some electrical grease just in case. Reset ECM again and waited. The light was back on in 3 days and the car started to feel funny when sitting at a light but it wasn't really bad.

Week 4. The car now hesitates at a light when in gear. I stahled out the other morning slowing down. In order to prevent that I throw it in Neutral when coming to a light and put it back into Drive when I have to take off. I notice that it happens when the brakes are being applied mainly. If I brake really hard and come to a stop quickly is when it feels like it's going to die. With the AC on it tends to just add to the problem.

I've checked all the hoses I can get to, I even replaced the PCV hose and the one going into the beginning of the throttle body just to be safe. I came home today and while the car was running, I put it into drive, let it rest against the parking stone and I got under the hood. (Yes, I'm crazy like that lol). I went around and started to "pinch" any of the vaccum lines I could get to while trying not to cook my fingers.Also I did not smell any exhaust or hear any whistles or usual sounds of an exhaust leak from the manifold. I can't really hear any vacuum leaks either.

This issue happens from morning till night. When I first start the car and back out of my parking space, it feels like it's about to stutter a little when I brake in reverse. I notice that the issue isn't as severe in cooler temps. I'm in South Florida so we are talking a difference between 80 degrees out and 90 lol.

I know the car doesn't have an "EGR" valve but was told that is a very likely suspect. So could it be the Canister Solenoid? Am I missing something?

On a side note. My belts have a slight squeek on cold starts and will SQUEEL when I turn on the AC. I notice that the timming of the squeek/squeel is not consistant with the RPM of the engine. The belts have about 40k on them. As they are squeeking/squealing the engine feels like it has extra drag on it till the noise goes away then it's all fine. I've tightened the alternator belt but noticed the other night that when it was squeeking, my lights were dim till the squeek went away.

I know this is a lot to read and I'm sorry, but I like to try and be as descriptive as possible.

Thanks! I'll be looking at it more this weekend now that I have time and I will try to come back with an update if anything changes!
 

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99 Kia Elan 1.8L, 17 Ford Edge Sport 2.7L V6, 15 Mustang 3.7L V6, 08 Harley Nightrain
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Welcome back to the forum.

It seems like you've been replacing MAF's when the actual problem was more likely something else such as a leak in the intake pipe between the MAF and the throttle body, or an intake manifold vacuum leak.

Sounds to me like you have some air flow that's not being metered by the MAF, such as a bad PCV valve, vacuum line leak, ........ would be a good idea to get a vacuum gauge on the manifold and check the vacuum at idle, and this would confirm if it is in fact a vacuum leak, and then you'll know to continue the hunt for it.
 

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Discussion Starter #3
Welcome back to the forum.

It seems like you've been replacing MAF's when the actual problem was more likely something else such as a leak in the intake pipe between the MAF and the throttle body, or an intake manifold vacuum leak.

Sounds to me like you have some air flow that's not being metered by the MAF, such as a bad PCV valve, vacuum line leak, ........ would be a good idea to get a vacuum gauge on the manifold and check the vacuum at idle, and this would confirm if it is in fact a vacuum leak, and then you'll know to continue the hunt for it.
You're probably right, I'm going to try and find a vaccum gauge today to use. My concern is if I figure out there's a leak, how do I find it if I can't really hear it? I know I can use a cigarette and see where the smoke gets sucked in or something along those lines. Inscents work too, and don't smell as bad :)

Now to find out what the values would be of the vaccum at idle...
 

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You're probably right, I'm going to try and find a vaccum gauge today to use. My concern is if I figure out there's a leak, how do I find it if I can't really hear it? I know I can use a cigarette and see where the smoke gets sucked in or something along those lines. Inscents work too, and don't smell as bad :)

Now to find out what the values would be of the vaccum at idle...
Take a look at the KiaTech web site, but I recall that it's 480mmHg (18.9 inHg).
 

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Discussion Starter #5
Take a look at the KiaTech web site, but I recall that it's 480mmHg (18.9 inHg).
I'll make a note of that. Thanks a ton! :) I'll keep you posted if we make any headway this weekend.

See, I knew I loved this forum for a reason!
 

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Bad iat sensor maybe.

Intake air temp. Its on the filter housing.
 

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Discussion Starter #7
Bad iat sensor maybe.

Intake air temp. Its on the filter housing.
Any idea whats a good way to diagnose that other than buying one? I'm on an extremely tight budget right now and I'm trying my best to troubleshoot with what I have.
 

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With 125k miles on it...and no mention by posters...You may have plugged up Catalytic converters causing back pressure... That would cause stumbling, strange codes,stalling, vacuum, and other problems... They can cause strange things to happen when bad... If you can get someone to read the pressure at the first O2 sensor "bung hole" (where the sensor is screwed in) it should be no higher than 2~3 pounds per square inch.

Your belts are most definitely bad and causing the alternator pulley to slip (dim lights and squealing)..

You said you swapped out the MAF ...New or another used one? If you got a used one it may also have been on a car that had problems... There is a specific spray cleaner just for MAFs that you can get at auto parts stores that may clean your "selection" of MAF sensors... One of these being cleaned may solve your problem also.. just a few thoughts.
Dave
 

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Discussion Starter #9
With 125k miles on it...and no mention by posters...You may have plugged up Catalytic converters causing back pressure... That would cause stumbling, strange codes,stalling, vacuum, and other problems... They can cause strange things to happen when bad... If you can get someone to read the pressure at the first O2 sensor "bung hole" (where the sensor is screwed in) it should be no higher than 2~3 pounds per square inch.

Your belts are most definitely bad and causing the alternator pulley to slip (dim lights and squealing)..

You said you swapped out the MAF ...New or another used one? If you got a used one it may also have been on a car that had problems... There is a specific spray cleaner just for MAFs that you can get at auto parts stores that may clean your "selection" of MAF sensors... One of these being cleaned may solve your problem also.. just a few thoughts.
Dave

I've considered the CAT to be a problem child as well, thought about whacking it a few good times with a hammer. If not, I have some flex tube to bypass it if need be. Thought the car accelerates fine for the most part and I've taken it up to and beyond 80mph lately so I know it's not clogged that bad. I just bypassed the CAT on a friends Sportage who was having similar issues and her truck runs like a top now.

When the belts were first done we had a squeeling problem with them and the mechanic that did them (Before I got the car) replaced them with OEM after 3 tries, saying that these cars were known for being picky on belts. Maybe I should bite the bullet & replace them.

The MAF was a Remanufactured one from Advanced Auto. A1 Cardone to be exact. I highly doubt it's the culprit still, considering the car doesn't act like it's not "Breathing" per say, it feels more like a vacuum issue.

I did the carb cleaner check yesterday and didn't notice anything. Next option is to start pulling sensors and the solenoid (EGR) to see if it clicks or not.
 

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I did the carb cleaner check yesterday and didn't notice anything. Next option is to start pulling sensors and the solenoid (EGR) to see if it clicks or not.
I know the car doesn't have an "EGR" valve but was told that is a very likely suspect.
Does it have an EGR ?
 

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Discussion Starter #11
Does it have an EGR ?
From everything I've read, no. There's a some sort of purge solenoid or something along the firewall that runs from the master cylinder to the canister and then from there into the intake. Sorry if I don't have the correct name off the top of my head :)
 

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I would be suspect of "The MAF was a Remanufactured one from Advanced Auto. A1 Cardone to be exact".

They have been "sourcing" manufactured" parts out of Mexico..
Like their "famous" Lifetime Remanufactured Alternators KNOWN to be bad...These "factories" replace only the most visible problem found and not wear items like brushes/and bearings. The clean them up and send them out as "remanufactured"

This has been found true for Advance and Autozone. I'm not sure about O'Reilly's..
I would like to know how a MAF sensor gets "remanufactured" and what part(s) they replaced... Sounds like the degreased used parts and boxed them.

btw...
You will have lower vacuum and "breathing" problems "if" the Cat(s) are plugged The engine's exhaust causes back pressure on the engine when the exhaust cycle tries to push the waste completely out and can't. Then the fuel/air intake cycle does not draw in as much (where the vacuum comes from). So a blocked/bricked/plugged Cat will cause idle/stumbling/lean fuel (exhaust gases trying to be reburnt again instead of fresh air/fuel).
Dave
 

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I would be suspect of "The MAF was a Remanufactured one from Advanced Auto. A1 Cardone to be exact".

They have been "sourcing" manufactured" parts out of Mexico..
Like their "famous" Lifetime Remanufactured Alternators KNOWN to be bad...These "factories" replace only the most visible problem found and not wear items like brushes/and bearings. The clean them up and send them out as "remanufactured"

This has been found true for Advance and Autozone. I'm not sure about O'Reilly's..
I would like to know how a MAF sensor gets "remanufactured" and what part(s) they replaced... Sounds like the degreased used parts and boxed them.

btw...
You will have lower vacuum and "breathing" problems "if" the Cat(s) are plugged The engine's exhaust causes back pressure on the engine when the exhaust cycle tries to push the waste completely out and can't. Then the fuel/air intake cycle does not draw in as much (where the vacuum comes from). So a blocked/bricked/plugged Cat will cause idle/stumbling/lean fuel (exhaust gases trying to be reburnt again instead of fresh air/fuel).
Dave
I somewhat agree, but logically this would be if I were getting a code for a Rich running system, not a Lean running system, no? If the pressure in the exhaust is too great for the waste to escape, wouldn't that mean a backup of rich air and not of clean air? Or am I just assuming that the ECM would be working logically in this case? :)
 

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Any idea whats a good way to diagnose that other than buying one? I'm on an extremely tight budget right now and I'm trying my best to troubleshoot with what I have.
The iat for the sephia is 16.00 dollars, so it will not break the bank. I am not sure of how to test it though. Have you signed up to kiatechinfo.com? Should have the procedure on there to test it.

I assume the iat takes the temp of the intake charge and with that information it helps determine the air/fuel ratio. Which if not running correctly could throw off your air/fuel ratio and cause a lean/rich condition throwing the above code.
 

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Discussion Starter #15
The iat for the sephia is 16.00 dollars, so it will not break the bank. I am not sure of how to test it though. Have you signed up to kiatechinfo.com? Should have the procedure on there to test it.

I assume the iat takes the temp of the intake charge and with that information it helps determine the air/fuel ratio. Which if not running correctly could throw off your air/fuel ratio and cause a lean/rich condition throwing the above code.
Yeah it may be worth while to change that too.
 

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Yeah it may be worth while to change that too.
The IAT is very easy to test with a multimeter and as 1fastkia said, the method and values can be found on KiaTech Info (see my sig for link).

The IAT provides the ambient air temperature which is used together with the MAF signal for a density compensation mass air flow value.
 

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I found this info, might be useful with your search

Basically this means that an oxygen sensor in bank 1 has detected a lean condition (too much oxygen in the exhaust). On V6/V8/V10 engines, Bank 1 is the side of the engine that has cylinder #1. The P0171 is one of the more common trouble codes.

This code is triggered by the first downstream (front) O2 sensor. The sensor provides a reading of the air:fuel ratio leaving the engine's cylinders, and the vehicles powertrain/engine control module (PCM/ECM) uses that reading and adjusts to keep the engine running at that optimum ratio of 14.7:1. If something is not right and the PCM cannot maintain the 14.7:1 ratio, but rather there is too much air, it triggers this code.


Causes

A code P0171 may mean that one or more of the following has happened:
•The MAF (Mass Air Flow) Sensor is dirty or faulty
Note: The use of "oiled" air filters may cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
•There could be a vacuum leak downstream of the MAF sensor
•Possible cracked vacuum or PCV line/connection
•Faulty or stuck open PCV valve
•Failed or faulty oxygen sensor (bank 1, sensor 1)
•Sticking/plugged or failed fuel injector
•Low fuel pressure (possible plugged/dirty fuel filter!)
•Exhaust leak between engine and first oxygen sensor


Possible Solutions

A lot of times, cleaning the MAF sensor and finding/fixing vacuum leaks fix the problem. If you're on a tight budget, start there, but that may not be the fix for certain. So, possible solutions include:
•Clean the MAF sensor. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling
•Inspect all vacuum and PCV hoses, replace/repair as required
•Inspect all hoses and connections in the air intake system
•Inspect and/or test the intake manifold gaskets for leakage
•Check for a dirty fuel filter and proper fuel pressure
•Ideally you'll want to monitor short and long term fuel trims using an advanced scan tool
 

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Discussion Starter #18
I found this info, might be useful with your search

Basically this means that an oxygen sensor in bank 1 has detected a lean condition (too much oxygen in the exhaust). On V6/V8/V10 engines, Bank 1 is the side of the engine that has cylinder #1. The P0171 is one of the more common trouble codes.

This code is triggered by the first downstream (front) O2 sensor. The sensor provides a reading of the air:fuel ratio leaving the engine's cylinders, and the vehicles powertrain/engine control module (PCM/ECM) uses that reading and adjusts to keep the engine running at that optimum ratio of 14.7:1. If something is not right and the PCM cannot maintain the 14.7:1 ratio, but rather there is too much air, it triggers this code.


Causes

A code P0171 may mean that one or more of the following has happened:
•The MAF (Mass Air Flow) Sensor is dirty or faulty
Note: The use of "oiled" air filters may cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
•There could be a vacuum leak downstream of the MAF sensor
•Possible cracked vacuum or PCV line/connection
•Faulty or stuck open PCV valve
•Failed or faulty oxygen sensor (bank 1, sensor 1)
•Sticking/plugged or failed fuel injector
•Low fuel pressure (possible plugged/dirty fuel filter!)
•Exhaust leak between engine and first oxygen sensor


Possible Solutions

A lot of times, cleaning the MAF sensor and finding/fixing vacuum leaks fix the problem. If you're on a tight budget, start there, but that may not be the fix for certain. So, possible solutions include:
•Clean the MAF sensor. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling
•Inspect all vacuum and PCV hoses, replace/repair as required
•Inspect all hoses and connections in the air intake system
•Inspect and/or test the intake manifold gaskets for leakage
•Check for a dirty fuel filter and proper fuel pressure
•Ideally you'll want to monitor short and long term fuel trims using an advanced scan tool

I've already gone over this information. Not to sound like an ass, but I started with this and that's how the MAF got replaced twice already, the 2nd replacement was a precaution but 2 bad MAF is highly unlikely considering when I changed it the first time the car at ran perfectly fine.

The code came, but the troubles didn't start till more than a week after that.

I don't have the funds to go replacing every sensor, buying every gauge and the time to run the gambit of checks on the car, hence why I was so descriptive in every action and reaction of the car.

If the problem was O2 sensor, Stuck Fuel Injectors or mostly anything else of the sort, the car would sputter more often, not accelorate as well and my fuel economy would go in the toilet. Honestly I'm still averaging between 28-31mpg with the car. I gauge it every week when I get gas, I top off and check my mileage to my Odometer AND the GPS I have in the car, reseting the trip each time.

I know if I sent this thing to a mechanic, it would be a minimum $700 bill just to replace a $19 part. I'd rather avoid that.

:)
 

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2015 Buick Verano "Leather Group", 2015 Kia Optima Hybrid
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An o2 sensor will cause nothing if it fails. You will most likely not notice anything. Fuel economy would suffer only a few to 5mpg, nothing you would really notice. You would not go from say 25mpg with ok sensors to 10 mpg, just would not happen.
If youve replaced the maf, (twice at that) its not this. How is the wiring to the maf? have you looked for rubbed wires, all the way to the ecu?

Of course we know you have not tested the iat yet, might wanna do that.

If you are complaining about the bill at the mechanic then you will have to break down everything, test every sensor that has to do with the air/fuel ratio, check o2 sensor, iat, fp regulator, and so much more.
This is why that bill would be XXX dollars cause of all the work associated with a n unknown cause to the issue. Its gotta be something.
So, unless you spending all the dough to a mechanic, better reserve sometime to test everything, and break down all the wiring associated if sensors test out good.

Its a lot of work sometimes, but that is why there are mechanics who have the time and knowledge to do this kinda thing. or you make time to do it yourself.

If your looking for anything else there really isn't. There is only so much associated with the AIR/FUEL ratio and what could cause it to lean out or richen up.
 

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Discussion Starter #20
An o2 sensor will cause nothing if it fails. You will most likely not notice anything. Fuel economy would suffer only a few to 5mpg, nothing you would really notice. You would not go from say 25mpg with ok sensors to 10 mpg, just would not happen.
If youve replaced the maf, (twice at that) its not this. How is the wiring to the maf? have you looked for rubbed wires, all the way to the ecu?

Of course we know you have not tested the iat yet, might wanna do that.

If you are complaining about the bill at the mechanic then you will have to break down everything, test every sensor that has to do with the air/fuel ratio, check o2 sensor, iat, fp regulator, and so much more.
This is why that bill would be XXX dollars cause of all the work associated with a n unknown cause to the issue. Its gotta be something.
So, unless you spending all the dough to a mechanic, better reserve sometime to test everything, and break down all the wiring associated if sensors test out good.

Its a lot of work sometimes, but that is why there are mechanics who have the time and knowledge to do this kinda thing. or you make time to do it yourself.

If your looking for anything else there really isn't. There is only so much associated with the AIR/FUEL ratio and what could cause it to lean out or richen up.
Would the ambient air temperature affect this? IN other words, say it's 75-80 out and the car runs smoother, but when it's 85+ it runs a little rougher. ?
 
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