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Discussion Starter · #1 · (Edited)
Kia Soul 2016 1.6L (base model) automatic,
While doing random test with an OBD scanner I noticed that the LTFT values are too high on Idle, and are dropping significantly when the rpm goes up.
The dealership inspection found no air leaks, and no other problem. since the engine light did not turned on and no errors detected in their scanner, they say all is ok.
The attached excel contain the data from a short car drive with various driving conditions.
I dont have enough knowledge to know which values are normal and which are not.
are the spark timing values looks ok?
can anyone try to see which other values are too high/low ?
The attached excel contain the data from a short car drive with various driving conditions.
 

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I don't see a particular issue with it. Those are pretty normal values. Your scanner is misleading you somewhat, Kia does not have LTFT STFT per say, they have Idle, and partial load trims so not sure which trims your data is interpreting as which but it is misguiding you a little. If I get a chance to today I will take a snapshot for you of what it looks like on a factory scanner. You want to look at the Lambda values more, only time it goes haywire on your chart is when you step off the gas after accelerating and that is perfectly normal. It is a lot easier to read these if your scanner will allow you to graph them rather than to chart the numbers. You might want to mention which engine and transmission you have also.
 

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Discussion Starter · #3 ·
I don't see a particular issue with it. Those are pretty normal values. Your scanner is misleading you somewhat, Kia does not have LTFT STFT per say, they have Idle, and partial load trims so not sure which trims your data is interpreting as which but it is misguiding you a little. If I get a chance to today I will take a snapshot for you of what it looks like on a factory scanner. You want to look at the Lambda values more, only time it goes haywire on your chart is when you step off the gas after accelerating and that is perfectly normal. It is a lot easier to read these if your scanner will allow you to graph them rather than to chart the numbers. You might want to mention which engine and transmission you have also.
Its Kia Soul 2016 1.6L (base model) automatic.
You mentioned Lambda values - What is the range of good Lambda values ?
If you can direct me which columns have most useful information I will create charts, I Just dont have a good idea which columns I should look at.
Thank you for your useful remarks !.
 

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Discussion Starter · #5 · (Edited)
First question, are you actually having issues, or did you just randomly look at some data and convince yourself that you are?
That's a good question, Ill have to go to more details to answer that.

1. It began at 2019 when I noticed that fuel consumption increase, It wend up from about 28 MPG to about 22 MPG, the OBD showed dramatic lean condition - Long tunf fuel trim is ~25% when engine runs in idle.
2. The dealership scanner showed engine error codes and they found a problem in the injectors - clogged injectors. they replaced it under warranty. everything went back to normal and I scanned LTFT to be under 5%.
3. After a about a year I noticed again that fuel consumption went up, scanned the LTFT to be about 12%
4. The dealership checked the car and this time they say they dont see any problems, so they did nothing.
5. Since then fuel consumption improved again to 28 MPG but the LTFT values increased a bit to about 15-17% on idle. I tried to use injector cleaners (saw a youtube by Scotty Kilmer recommended that) It didnt change anything.
6. Last year I noticed a new noise appear at 1500-1600 rpm, when I slowly accelerate. Its like a soft noise of knoking from the engine. Other than that everything looks and sound normal.

I will add the diagnosis results of the dealership for both time the car was there.

During this whole saga I never saw the check engine lights turned on or any engine error codes in the OBD scanner.
AFAIK lean engine for a long time can damage other components in the car such as the catalytic converter, So if there is a problem I want to solve it as soon as possible.
 

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Your case sounds rather rare. For starters I have seen maybe a handful of injectors fail on Kias period and that's GDI and MPI engines and never replaced all 4 on one car, have done 2 at once but one would be worse than the other and was probably a problem before the 2nd failure that made the car really act up. The tech who wrote the diagnosis sounds pretty competent and stated all relevant items to your car so there had to be sound reason to believe all 4 injectors failed I just have never seen it on a Kia or any other car for that matter where all injectors failed unless some kind of fuel contamination came to play here. It would be like saying all 4 of your coils burned out at the same time, it just doesn't happen because the probabilities of that are somewhere better than a lotto ticket.
On the Kia factory scanner (KDS he refers to on your paperwork) you will see idle and part load fuel trims and Lambda values as well as watch the upstream A/F sensor. I usually take a test drive with the parameters I want to see in graph mode and I can stop it and replay it at any time if I see a spike in the graph. The Lambda correction value should be at 1.00, any variance from that is your fuel trim adjusting rich or lean and that is normal unless it goes haywire during idle or steady driving or even steady acceleration. I'll try to take a 2nd look at your data but it is hard to scroll around on it. About the only data points I would want to see to start with (for the issue you are describing) would be: fuel pressure actual and requested side by side, O2 bank1 sensor 1 (it is an Air Fuel sensor but they still call them O2s) on the Soul you should see something like 1.48-1.5 volts with a fluctuation any time you floor it or get off the gas, accelerator position % (not throttle position, the TB goes full open even during mild acceleration) and the Lambda values along with RPM. I wonder if you have a MAP sensor issue or there is a potential small vacuum leak. Perhaps it would be best to check out the MAP and do a quick smoke test on the intake. This might take some deeper digging, it could be even mechanical like cam timing acting up but not for long enough to throw a code or even the stupid purge valve that is failing but not enough to throw a code.
Maybe this will help, pictures attached
 

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Discussion Starter · #7 ·
Wow, thank you so much for digging dip into it and for the detailed advises.
I'm sorry about the data format being hard to read, I have it on Excel page but the forum system is very limiting in the file types it allows to upload.

Few question I have :
1. The Long Turn Fuel values which goes up to 17%, isn't that a big issue ? what value will trigger an Error or Engine check light in the Soul ?
2. I noticed that the fuel rail pressure is thousands of PSI ... is it normal ?
3. In the first diagnosis the dealership mention "Ignition Timing" retarding, Is it the "SPARKADV" my scanner show ? and if so, are the value I measure in range ?

BTW, I replaces the Purge valve couple of years ago when there was a suspect it might cause the problem, I'll check it again.
And I just remembered that in a later phone call with Kia Usa they mentioned that they see that dealership did replaced 2 injectors. so Im not so sure they did replace all 4.

I created the graphs with the fields you suggested, I added a big chart that contain all the fields after I normalized the values to make it fit in one chart.
I also attached the raw text file created by the scanner contains freeze frames of data. Just in case it might help.

Again thank you so much for the useful information !
 

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Wow, thank you so much for digging dip into it and for the detailed advises.
I'm sorry about the data format being hard to read, I have it on Excel page but the forum system is very limiting in the file types it allows to upload.

Few question I have :
1. The Long Turn Fuel values which goes up to 17%, isn't that a big issue ? what value will trigger an Error or Engine check light in the Soul ?
2. I noticed that the fuel rail pressure is thousands of PSI ... is it normal ?
3. In the first diagnosis the dealership mention "Ignition Timing" retarding, Is it the "SPARKADV" my scanner show ? and if so, are the value I measure in range ?

BTW, I replaces the Purge valve couple of years ago when there was a suspect it might cause the problem, I'll check it again.
And I just remembered that in a later phone call with Kia Usa they mentioned that they see that dealership did replaced 2 injectors. so Im not so sure they did replace all 4.

I created the graphs with the fields you suggested, I added a big chart that contain all the fields after I normalized the values to make it fit in one chart.
I also attached the raw text file created by the scanner contains freeze frames of data. Just in case it might help.

Again thank you so much for the useful information !
What is the mileage on the car?

Also, what is your oil change frequency & do you use an OEM filter or 3rd party brand?

Was curious too on your MPG take. Fuel economy usually goes down in winter months, from extra idling & engine strain etc + winter blend fuel. I've tracked mine for 8 years and same pattern, fuel economy will drop up to 4 mpg.
 
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Discussion Starter · #9 · (Edited)
What is the mileage on the car?

Also, what is your oil change frequency & do you use an OEM filter or 3rd party brand?

Was curious too on your MPG take. Fuel economy usually goes down in winter months, from extra idling & engine strain etc + winter blend fuel. I've tracked mine for 8 years and same pattern, fuel economy will drop up to 4 mpg.
The car have 57000 miles, I do oil changes every 5000-6000 miles , I think I missed only one of them and did it at 7000 miles due to hurricane Irma. I service the car at the dealership so I dont know what kind of oil and filter they put inside.
I'm from Florida so we don't really have winter here :), but the car has 95% of its rides inside the city.
I do use the "ECO" option which does make the car much less "zippy" but I'm very conservative driver and very easy on the pedal, otherwise i would have buy the car with the bigger engine. I there is a problem with the car loosing power in acceleration I will probably wont feel it.
What is strange is that lately with the LTFT values go higher I think I see slight improvement in the fuel economy. there are times when the tank was empty and the meter showed average of above 29 MPG.
Im not sure if there was a change in the way I drive (I dont feel any change but its very subjective) or it is something change with the car.
 

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The car have 57000 miles, I do oil changes every 5000-6000 miles, I think I missed only one of them and did it at 7000 miles due to hurricane Irma.
I'm from Florida so we don't really have winter here :), but the car has 95% of its rides inside the city.
I do use the "ECO" option which does make the car much less "zippy" but I'm very conservative driver and very easy on the pedal, otherwise i would have buy the car with the bigger engine. I there is a problem with the car loosing power in acceleration I will probably wont feel it.
What is strange is that lately with the LTFT values go higher I think I see slight improvement in the fuel economy. there are times when the tank was empty and the meter showed average of above 29 MPG.
Im not sure if there was a change in the way I drive (I dont feel any change but its very subjective) or it is something change with the car.
Thanks Benoved. Since your miles are mostly city & hot climate, you would be considered "severe" usage and that oil change interval would go down to around 3,000 miles.

Your owners manual talks about that and Kia sent letters reminding owners.
 
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Discussion Starter · #11 ·
Thanks Benoved. Since your miles are mostly city & hot climate, you would be considered "severe" usage and that oil change interval would go down to around 3,000 miles.

Your owners manual talks about that and Kia sent letters reminding owners.
This was actually one of the weirdest things I faced when moved to the US. this was the first time I faced the fact that dealerships here recommend oil change every 3000 Miles which are 5000 Km
Before coming here I lived In a hot country with worse climate than Florida, where ALL new cars from the last decade change oil no less than 15000 Km (~ 9000 Miles) (as recommended by the manufacturers), many cars moved to 20000 Km and 25000 Km.
My 98 Suzuki Esteem was old where the manufacturer recommended every 10000 Km. My Mechanic told me that new cars with much better engine manufacture precision , and much better oil technology in new cars allowed greater gap between oil changes.
It was so confusing to understand that in US many change oil every 3000 miles. I couldn't understand why.
I read the manual and the manufacturer recommends oil changes each 7500 Mile, and every 5000 miles in places of sever driving conditions exist. what are sever conditions ? no one will tell you, its open to interpretations.
There is no mention of oil change every 3000, and to me it feels too frequent, so I decided to stick with changing oil every 5000 Miles. and Ill start do it myself, I have no confidence at the dealership, but this is a different story.
 

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This was actually one of the weirdest things I faced when moved to the US. this was the first time I faced the fact that dealerships here recommend oil change every 3000 Miles which are 5000 Km
Before coming here I lived In a hot country with worse climate than Florida, where ALL new cars from the last decade change oil no less than 15000 Km (~ 9000 Miles) (as recommended by the manufacturers), many cars moved to 20000 Km and 25000 Km.
My 98 Suzuki Esteem was old where the manufacturer recommended every 10000 Km. My Mechanic told me that new cars with much better engine manufacture precision , and much better oil technology in new cars allowed greater gap between oil changes.
It was so confusing to understand that in US many change oil every 3000 miles. I couldn't understand why.
I read the manual and the manufacturer recommends oil changes each 7500 Mile, and every 5000 miles in places of sever driving conditions exist. what are sever conditions ? no one will tell you, its open to interpretations.
There is no mention of oil change every 3000, and to me it feels too frequent, so I decided to stick with changing oil every 5000 Miles. and Ill start do it myself, I have no confidence at the dealership, but this is a different story.
I hear ya barkin' big dog. I get it, and totally respect your view on this.

I'll attach the letter from KIA on oil (sorry it's not better quality--skip to the next post where rhysoul was kind enough to post a clearer copy). They discuss Severe Usage and make the statement "Severe Usage Conditions are now typical for many and perhaps most American drivers."

I'm more of a "read between the lines" guy and believe the real message is that clean, fresh oil is going to be key to your engine lasting a long time. As many on this forum have taught me, oil is cheap in the scheme of things, especially if you can change your own.

All the best!
 

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@benoved,

Curious. What scanner and software are you using? What country did you come from?

With the kind of driving you are doing, you should think about cleaning the back of your intake valves. Yours is a GDI engine and requires extra maintenance.
 
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Discussion Starter · #16 ·
@benoved,

Curious. What scanner and software are you using? What country did you come from?

With the kind of driving you are doing, you should think about cleaning the back of your intake valves. Yours is a GDI engine and requires extra maintenance.
I'm using Autel 519 scanner, and the software is a code I wrote in Python + Jupyter Notebook - had to use my software engineering experience to work with the raw data this cheap scanner produces (the horrible text file I attached in earlier reply message). I came from Israel.

I will look for video guides for intake valves cleaning, thank you !
 

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I will look for video guides for intake valves cleaning, thank you !
A lot of people seem to like a product called CRC GDI Intake Valve Cleaner, and there’s another good one from Berryman’s. You spray it through the intake while keeping the rpm’s up around 2,500 or so. There’s a lot of YouTube videos on people showing how to use it.

If they’re used on a regular basis, they can help keep the intake valves clean, but if they’re already dirty, a spray like that isn’t going to do much.

The reason why people use these products on GDI engines is because the fuel is directly injected into the cylinder and doesn’t wash over the back side of the valves like it would in a multi port injection engine, so the valves tend to get carbon buildup and eventually it will cause drivability issues.

Even if you’re not having any issues, @westslope has a good thread to read to get a better idea of the extra proactive maintenance these dirty GDI engines require. By the way, it’s not just Kia. GDI engines from any manufacturer need a bit more maintenance, mainly just more frequent oil changes.

 
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Discussion Starter · #18 ·
A lot of people seem to like a product called CRC GDI Intake Valve Cleaner, and there’s another good one from Berryman’s. You spray it through the intake while keeping the rpm’s up around 2,500 or so. There’s a lot of YouTube videos on people showing how to use it.

If they’re used on a regular basis, they can help keep the intake valves clean, but if they’re already dirty, a spray like that isn’t going to do much.

The reason why people use these products on GDI engines is because the fuel is directly injected into the cylinder and doesn’t wash over the back side of the valves like it would in a multi port injection engine, so the valves tend to get carbon buildup and eventually it will cause drivability issues.

Even if you’re not having any issues, @westslope has a good thread to read to get a better idea of the extra proactive maintenance these dirty GDI engines require. By the way, it’s not just Kia. GDI engines from any manufacturer need a bit more maintenance, mainly just more frequent oil changes.

Thank you for the helpful information.
I used few Injector cleaners like the Lucas etc. they claim that they clean the fuel system, do they clean the cylinders too ?
Oh, one more question - can I control the RPM from the engine bay like the older cars ?
 

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Thank you for the helpful information.
I used few Injector cleaners like the Lucas etc. they claim that they clean the fuel system, do they clean the cylinders too ?
Oh, one more question - can I control the RPM from the engine bay like the older cars ?
Fuel system cleaners can help keep the injectors and combustion chamber clean. I add one (Techron Complete) to my tank a few days before I do an oil change. Do they actually work, I don’t know, but it doesn’t cost much and it makes me feel better using one 😀

No the throttle is electronic. It’s either a two person job, or rig up something like an adjustable rod (against the seat and gas pedal) to keep the rpm’s at around 2,000-2,500.
 

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This may sound crazy but... You said you drive the car with very light throttle all the time. Have you tried a few hard runs to redline? Aka a Italian tuneup??
 
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