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2015 Kia Soul 1.6L V4 2WD GDI
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Discussion Starter · #1 ·
Hey everyone, figured I would attempt to get some insight before doing anything to the car. I have a 2015 Kia Soul 1.6L with just under 100k miles. Had a P2191 code come up for a lean condition under load. Took it to the dealer and they said all the injectors were fouled and they wanted to replace all of them.

Thought how could that have happened, and tried SeaFoam to clean the injectors. It worked, and the car ran great for a little more than a week without any codes at all. Recently the code came back, and the engine runs noticeably rougher than usual.

I'm thinking there's a lack of fuel pressure under load, as it's on the original fuel pump and filter. More just curious if anyone has heard of this before and if I'm going in the right direction. The only other code on it is a C1555, and a P050A code popped up yesterday morning but it was in the low 30s in Florida so I don't think that one's related.

Any help would be appreciated, thanks!
 

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I'd let the dealer replace them before the warranty runs out. :)
 

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Maybe not the first owner?
 

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Discussion Starter · #6 · (Edited)
Did something change? What happened to ten years or 100K miles for the powertrain warranty?
I'll look into the warranty, it may still be on it. Got it new and always had it serviced by Kia so yeah it should actually be covered.

Dealer didn't mention it at the time and wanted to charge a couple thousand for all new injectors and plugs.
 

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2011 Forte SX 2.4L (thankfully MPI) A/T 144K miles
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I'd be surprised if injectors were covered under powertrain. If you read the barely visible print at the bottom of your warranty, you will probably find the injectors and a bunch of other stuff on the exclusion list.

Did this stealership by any chance tell you how they diagnosed that the issue was the injectors? I'm expecting the answer to be no. I think the flavor of your vehicle's Gamma engine is GDI, which makes the far more likely suspect to be the high pressure fuel pump. I've never read a report of multiple injectors failing so early, but have seen multiple accounts of high pressure pumps failing far sooner than one would expect them to.

However the important thing is that your vehicle needs to be properly diagnosed, which I'm suspecting has not yet happened. One piece of diagnostic information which might be very helpful is HPFP fuel rail pressure, which is available via a live data OBD reader. I recommend taking a close look at that pressure, and compare it to the range specified in the service manual.
 

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2015 Kia Soul 1.6L V4 2WD GDI
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Discussion Starter · #8 ·
I'd be surprised if injectors were covered under powertrain. If you read the barely visible print at the bottom of your warranty, you will probably find the injectors and a bunch of other stuff on the exclusion list.

Did this stealership by any chance tell you how they diagnosed that the issue was the injectors? I'm expecting the answer to be no. I think the flavor of your vehicle's Gamma engine is GDI, which makes the far more likely suspect to be the high pressure fuel pump. I've never read a report of multiple injectors failing so early, but have seen multiple accounts of high pressure pumps failing far sooner than one would expect them to.

However the important thing is that your vehicle needs to be properly diagnosed, which I'm suspecting has not yet happened. One piece of diagnostic information which might be very helpful is HPFP fuel rail pressure, which is available via a live data OBD reader. I recommend taking a close look at that pressure, and compare it to the range specified in the service manual.
That's what I was thinking, a fuel pressure problem, either with the filter or pump. I found a nice Bosch pump and a new filter and planned on replacing both just because of the labor involved. May also take it to a local trusted shop for a second opinion. But as soon as they said all 4 injectors and plugs needed to be replaced I became pretty suspicious. And if it is a fuel pressure problem, new injectors wouldn't even fix it.
 

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... I found a nice Bosch pump and a new filter and planned on replacing both just because of the labor involved. ...
Again, if your vehicle is GDI (usually stamped on the engine deco cover), then there are 2 fuel pumps - a low pressure pump in the gas tank, and also a high pressure pump located somewhere on top of the engine. In any case, it's a much better approach to diagnose before replacing ANY parts. But as always, your vehicle, your choice.
 

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2015 Kia Soul 1.6L V4 2WD GDI
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Discussion Starter · #10 ·
Again, if your vehicle is GDI (usually stamped on the engine deco cover), then there are 2 fuel pumps - a low pressure pump in the gas tank, and also a high pressure pump located somewhere on top of the engine. In any case, it's a much better approach to diagnose before replacing ANY parts. But as always, your vehicle, your choice.
I'll check the high pressure pump pressure just to see, but I will likely take it to a more trusted mechanic to get it properly diagnosed and repaired. Wasn't actually aware that there were 2 pumps on the GDI, I assumed the in tank one was the high pressure one. I'll keep this thread updated when I get more information, thanks everyone for the valuable help.
 

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Discussion Starter · #11 ·
I'll check the high pressure pump pressure just to see, but I will likely take it to a more trusted mechanic to get it properly diagnosed and repaired. Wasn't actually aware that there were 2 pumps on the GDI, I assumed the in tank one was the high pressure one. I'll keep this thread updated when I get more information, thanks everyone for the valuable help.
High pressure rail measures 2162 psi under load, and according to Kia the max should be 2175.6 psi. I would think that would be fine. At idle it's around 560 psi.

I don't see any metrics for the low pressure on the scan tool.
 

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High pressure rail measures 2162 psi under load, and according to Kia the max should be 2175.6 psi. I would think that would be fine. At idle it's around 560 psi. ...
Very good to see those first 2 numbers, but it would complete the picture if you can find the spec pressure range at idle. Although the 560 is probably good, it's always best to confirm everything that you can.


... I don't see any metrics for the low pressure on the scan tool.
It's not available in OBD, however it's logically not needed if the fuel rail pressure is within spec, because the HPFP is in series with, and is being fed from the in-tank pump. So if the rail pressure is good, then it must be that both of the pumps it depends on are producing good pressure.

What fuel trim values, particularly the STFT, are you seeing on your scan tool? Also, how is the vehicle running now, compared to before the lean code first showed up?
 

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Discussion Starter · #13 · (Edited)
Very good to see those first 2 numbers, but it would complete the picture if you can find the spec pressure range at idle. Although the 560 is probably good, it's always best to confirm everything that you can.



It's not available in OBD, however it's logically not needed if the fuel rail pressure is within spec, because the HPFP is in series with, and is being fed from the in-tank pump. So if the rail pressure is good, then it must be that both of the pumps it depends on are producing good pressure.

What fuel trim values, particularly the STFT, are you seeing on your scan tool? Also, how is the vehicle running now, compared to before the lean code first showed up?
That's good information to know, thanks. The service manual has the HPFP minimum pressure as 290.1. However it doesn't really say that's supposed to be the idle pressure, so I'll see if I can find some more info on that. I'll also check STFT and report back. It runs noticeably rough at idle but only at times, otherwise it actually seems to drive just fine. At least nothing glaringly obvious. The roughness at idle is really the only thing. Maybe it's a little more bogged down with accelerating but that might just be my imagination. I'm just curious what's causing the injectors to get plugged up, which is why I was thinking fuel filter. The pressure seems normal under load though so that's interesting.

That being said, I haven't actually looked at the injectors myself. Only taking the word of the dealership saying they were all plugged. I think I believe them though, but I think something is causing it. I don't see all 4 Injectors going at the same time as normal.
 

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... It runs noticeably rough at idle but only at times, otherwise it actually seems to drive just fine. At least nothing glaringly obvious. The roughness at idle is really the only thing. ...
First off, that doesn't sound like a fouled injector issue to me. Deposits fouling the injector tips are not bits of loose material floating around - they are solid, thin layers which build up over time. And if such deposits are present and cause a symptom such as rough idle, that condition is continuous, not intermittent and random as you are currently seeing. And I suspect that the 'improvement' you observed after adding Seafoam was just a coincidence.

This stealership was just throwing darts, and the dart they threw landed on the injector circle. Guessing is nice and easy - no thinking required, and even a caveman can do it. And here's a side note that their story is a pile of crap. GDI injectors would never be replaced if the problem is simply deposits. These parts are so expensive (over $100 each), that no honest and respectable shop would ever replace them, when simply cleaning off the deposits makes them like new. Total BS, all the way around.

An intermittent type of problem like this is typically more difficult to diagnose, but one very helpful aspect here is that you have the fuel rail pressure available to monitor. And that's quite useful in this case because when it idles rough and the fuel rail pressure doesn't drop, you know it cannot be a fuel pump or filter issue. So you should definitely watch that pressure when it runs rough at idle, and compare it to when it's idling ok.

Just a guess at this point (hey, I can do it too), but I suspect this rough idle will turn out to not be a fuel-related issue. And if so, that would leave a bunch of other possibilities - spark plugs, tired O2 sensor, and a number of others as well. But I don't replace parts on guesswork, and always believe diagnosis is the key to resolving a problem.

One thing not discussed yet is the electrical problem you mentioned in your OP. Can you describe what that was, and all of the symptoms that were happening before you took it in? And, aside from that electrical issue, please post if there were any other performance related problems with this vehicle in the recent past as well.
 

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Discussion Starter · #15 ·
First off, that doesn't sound like a fouled injector issue to me. Deposits fouling the injector tips are not bits of loose material floating around - they are solid, thin layers which build up over time. And if such deposits are present and cause a symptom such as rough idle, that condition is continuous, not intermittent and random as you are currently seeing. And I suspect that the 'improvement' you observed after adding Seafoam was just a coincidence.

This stealership was just throwing darts, and the dart they threw landed on the injector circle. Guessing is nice and easy - no thinking required, and even a caveman can do it. And here's a side note that their story is a pile of crap. GDI injectors would never be replaced if the problem is simply deposits. These parts are so expensive (over $100 each), that no honest and respectable shop would ever replace them, when simply cleaning off the deposits makes them like new. Total BS, all the way around.

An intermittent type of problem like this is typically more difficult to diagnose, but one very helpful aspect here is that you have the fuel rail pressure available to monitor. And that's quite useful in this case because when it idles rough and the fuel rail pressure doesn't drop, you know it cannot be a fuel pump or filter issue. So you should definitely watch that pressure when it runs rough at idle, and compare it to when it's idling ok.

Just a guess at this point (hey, I can do it too), but I suspect this rough idle will turn out to not be a fuel-related issue. And if so, that would leave a bunch of other possibilities - spark plugs, tired O2 sensor, and a number of others as well. But I don't replace parts on guesswork, and always believe diagnosis is the key to resolving a problem.

One thing not discussed yet is the electrical problem you mentioned in your OP. Can you describe what that was, and all of the symptoms that were happening before you took it in? And, aside from that electrical issue, please post if there were any other performance related problems with this vehicle in the recent past as well.
All good information to know, I knew the injectors could be cleaned and run like new, but not that the fouling would be a long term thing with thin layers and not just particles blocking the port that could've come out of a dirty filter.

What seems to be a little confusing at least for me is the lean under load code. Unless the pressure isn't getting past the injectors or something, I don't think it should be running lean with full pressure. Unless it is an air problem.

Below are some photos of the readings of short term and long term fuel trim at a few different fuel pressures. The STFT seems to hover around 0% but has gone as low as -6.25% when idle and as high as 8.7% when under load. It creeps up when sitting at a light from the -2 or -5 to 0%. Don't have enough experience to know if these numbers look normal or not.

I'll see if the pressures change at all with the idle issue and post back.
117506
117507
 

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Wow, that's some really helpful data you posted there! The STFT numbers look quite normal, especially the first set, but LTFT is off-the-wall high (LTFT should always be in proximity to STFT). That condition is often caused by a vacuum leak, which you can first check for visually by looking for cracked or partially detached vacuum hoses, and also listening for hissing noise. Then if nothing good comes from the visual check, a more comprehensive test is done by spraying carb cleaner, propane, etc, around the engine to see if the rpms go up at any point during that process.

I see a partially hidden vacuum gauge in your pic, but it's not very meaningful without knowing what the concurrent rpm reading is. If you're willing to take the time to rerun the above testing, after first adding a MAP/VACUUM (either one, or both is better) and RPM graph to the fuel trim graphs, that might be helpful in confirming a vacuum issue.
 

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Discussion Starter · #17 ·
Wow, that's some really helpful data you posted there! The STFT numbers look quite normal, especially the first set, but LTFT is off-the-wall high (LTFT should always be in proximity to STFT). That condition is often caused by a vacuum leak, which you can first check for visually by looking for cracked or partially detached vacuum hoses, and also listening for hissing noise. Then if nothing good comes from the visual check, a more comprehensive test is done by spraying carb cleaner, propane, etc, around the engine to see if the rpms go up at any point during that process.

I see a partially hidden vacuum gauge in your pic, but it's not very meaningful without knowing what the concurrent rpm reading is. If you're willing to take the time to rerun the above testing, after first adding a MAP/VACUUM (either one, or both is better) and RPM graph to the fuel trim graphs, that might be helpful in confirming a vacuum issue.
If this whole thing turns out to just be a vacuum leak I'll owe you 😂 anyway, below are some photos with the requested info. I believe the Intake gauge is the MAP. At idle, the vacuum goes as high as 25 in/Hg, and as soon as the gas pedal is pushed it immediately drops close to 0. In terms of the electrical issue you mentioned, I don't remember mentioning one earlier, but there doesn't seem to be one.
117508
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I was actually looking for graphs, like the ones that are being displayed for the fuel trims, but there's no need to knock yourself out over this. I think it's a better investment of your time at this point to try looking for a vacuum leak, because that's the most common way those out-of-sync fuel trims happens.

And sorry about that question about the electrical issue. I've been spending time concurrently with another guy on a completely different problem, and he was the one who had a prior electrical problem. So this was simply a case of me getting my wires crossed :)
 

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Discussion Starter · #19 ·
I was actually looking for graphs, like the ones that are being displayed for the fuel trims, but there's no need to knock yourself out over this. I think it's a better investment of your time at this point to try looking for a vacuum leak, because that's the most common way those out-of-sync fuel trims happens.

And sorry about that question about the electrical issue. I've been spending time concurrently with another guy on a completely different problem, and he was the one who had a prior electrical problem. So this was simply a case of me getting my wires crossed :)
Oh, sorry about that. If I can't find a vacuum leak I'll do it over again with the graphs, but I think you might be right about this. I'll take a look around and see what I find.
 

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Discussion Starter · #20 ·
Oh, sorry about that. If I can't find a vacuum leak I'll do it over again with the graphs, but I think you might be right about this. I'll take a look around and see what I find.
I haven't found any vacuum leaks yet, but I was thinking, because the engine uses a MAP instead of a MAF, would a vacuum leak even matter? I also checked the PCV valve because another P2191 thread mentioned it, tested it according to the service manual and it does seem to be good. I have engine vacuum if I unscrew it from the manifold and plug it back into the vacuum line, and there's movement when pushed with a pin as the manual describes.

Think I might just end up taking it into the local shop on Monday and see what they say. LTFT stayed around 40% through the PCV test, if that means anything.
 
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