Hyundai Forums banner

1 - 12 of 12 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter #1
Hey all,If this issue has been previously covered, feel free to just drop a URL.
Car is a 2017 Santa-Fe sport 2.0T with ~71,000 miles.
The wife was telling me that sometimes the car turns over for a few seconds longer than usual before it starts.
I plugged in my BT OBD reader (using the torque app) to check for codes when we went for a drive, it shows a pending fault for P0172 and does not clear.
The CEL is NOT on. nor was it on prior to me attempting to clear the code.
I watched the AFR readout as we drove and noted that while it generally stayed in the 14 range like usual, it would sometimes show 25 for a few seconds and then snap back to 14ish.
Oddly enough this seemed to start after i changed the oil? I don't really see how that could be related but i wanted to mention that in the event it could be.
Before this car I have always owned Chevy's so I am pretty unfamiliar with Hyundai's and how one should go about diagnosing faulty sensors/etc. My initial thought would be of course an O2 sensor going out because its showing a rich condition and not a lean one that is usually associated with a dirty MAF, but input from someone who is "in the know" would be greatly appreciated. Thanks in advance.
Tom
 

·
Registered
Joined
·
4 Posts
Discussion Starter #3
What is the diagnostic code description?
It is code P0172 for a bank one rich condition. I was watching the commanded Vs measured AFR on the way to work this morning and while commanded never went over 15, sometimes the measured would get as high as 25! It's no longer showing a code but the car is drinking gas like crazy, I'm getting about 250 miles on a full tank now and that's 90% highway driving and driving like a grandma in eco mode. I guess I should be asking if it's common for these cars to get shitty gas mileage...i definately was expecting better from a 2.0T, the VW I traded in for this was also a 2.0T and got significantly better mpg
 

·
Registered
Joined
·
4 Posts
Discussion Starter #4
I always use 93 octane fuel from a quality gas station such as shell or mobile so I doubt fuel is an issue but I'm starting to wonder if I have a fuel delivery issue such as a dirty injector,failing FPR,filter,pump...etc...im wondering if it's worth my time to check out the condition of the MAF? Buy an O2 sensor to swap in to see if that changes things,can something as simple as a dirty airbox filter cause things like this to happen? I don't know how picky Hyundai cars are,first time owning one...possibly last if I can't figure this out,even with gas being reasonable right now I still can't afford to fill up every day,I'm literally getting the same MPG from this 3 year old 2.0 as I would in my 10 year old 5.3...crazy
 

·
Registered
Joined
·
4 Posts
Discussion Starter #5
One more oddity to point out,I noticed that under load the AFR was generally on point but when coasting or idling that's when the numbers jump into the mid to high 20 range,that makes me circle back to the intake side of things like maybe I have excessive carbon buildup in the throttle body or again,the MAF is dirty...im not sure but I need to get to the bottom of this soon
 

·
Registered
Joined
·
7,904 Posts
When you let off the gas the ECU sets the fuel injectors to idle values. That's why it goes lean. What are your primary O2 sensor votlage values when cursing. Should be going .05v to .750v or so. Hard to see as it happens so fast and the OBDII read out is just wherever it is in a cycle.
 

·
Registered
Joined
·
230 Posts
If I understand this correctly, the O2 or air fuel ration sensor, is saying the engine is running rich and it is using fuel at a high rate. Wouldn't this suggest the O2 sensor is reading correctly? Normally a dirty air filter will not cause a rich condition as the computer should compensate but it sounds like you are suggesting the air filter may be dirty. If you don't know when it was last changed, why not just change it?

Short term fuel trims go into negative numbers when the computer believes the engine is running rich. Are these numbers you are quoting negative?
 

·
Registered
Joined
·
7,904 Posts
If it is indeed running too rich the O2 sensor voltage will be stuck high and not cycling down below .5v, the LTFT would be really high negative too.
 

·
Registered
Joined
·
7,904 Posts
I've change02 sensor before and no change in behavior. The last one I let fail before changing it. But you could see it really slowed down on the switching between high and low voltage. Eventually it quit and the ECU sent a default value. The car still ran good but the gas mileage was down a bit. But one they quit they set a slow response code.

My Accent is currently on the OE O2. I took it out at 100k and put in an aftermarket D
Bosch. It failed at 50k miles and I out the original one back in. Still on it at 175k miles (-50K) total.
 

·
Registered
2013 Hyundai Santa Fe Sport
Joined
·
2,247 Posts
Another member had occasional hard starts and turned out to be the in tank fuel pump.

A scan tool is required to check fuel system pressures after the pump shuts off. Fire some reason Hyundai did not think to include a Schrader valve on the fuel rail that a cheapo mechanical gauge could connect to.

Sent from my SM-G965U1 using Tapatalk
 
1 - 12 of 12 Posts
Top