P0300 & P219A codes

ktuck · April 12, 2024

I have a 2017 Silverado 1500 LT with a 5.3L with 114.000 miles that I bought from the original owner two years ago. I am sorry for the length of this post as I have tried to give the briefest but comprehensive analysis possible. I began noticing random misfires on occasions about 6 months ago but they have became more frequent and now are not intermittent anymore but constant. I currently have a steady CEL and codes P0300 and P219A. It shows up on light to moderate acceleration. I took it to a GM tech who suggested decarbonizing the engine. It made no difference at all, so he then suggested replacing the injectors. I did that myself to save a couple bucks and used GM injectors. In the last 6 months I have had two new sets of AC plugs in it and all the plug wires. I had a coil pack failure on cyl #1 so I replaced it and the misfire there went away. Erratic misfires began to start up again so I replaced all the other coil packs as well but the problem remained. The GM tech now thinks I have a collapsed lifter issue. I pulled both valve covers and inspected rockers, lifters and valve springs...no problems found. The inside of the engine looks pristine. There are no wobbly rockers and when spinning the engine over, all 16 valves appear to be opening consistent to all the others. Does not appear to have any wiped lobes or bent push rods. The original owner changed oil religiously at 3K intervals and I have followed that pattern myself. I drained the oil pan and looked for any traces of metal in the oil and found absolutely nothing. The oil is still very clean and clear and easy to see if contaminated. My scanner shows cylinders 2 and 5 as the chronic misfires I have switched plugs, wires and coil packs from good firing cylinders to see if the misfire will move to those cylinders but the misfires stay with 2 and 5. Since both are non-AFM cylinders, it kinda counters the GM techs theory of lifter problem, especially since visual inspection revealed nothing. Another data concern are the fuel trims. Bank 1 LTFT is around -15% and Bank 2 LTFT is around -28% which indicates a rich condition. I am puzzled that with the high negative LTFT, all the plugs are light colored almost white and certainly don't show a rich condition. Are the O2 sensors somehow being fooled? Their numbers look normal. The high fuel pressure is running around 480-600. The low fuel pressure jumps around while driving, I see it go as low as 25 and as high as 63...it never really holds steady very long, is that normal or possibly a sign of a fuel delivery issue? One more thing I'll throw out there, when it is missing and bucking on light load acceleration, if I kick it down and floor it, it takes off without any hesitation and runs strong and smooth. That seems kind of odd to me considering the multiple misfires. What am I overlooking here? I welcome any thoughts or ideas about this chronic misfire condition.

Buckwild27 · April 12, 2024

How is the wiring to the coil packs?

When changing the plugs did you double check the plug gap?

And have insured the wire is firmly snapped on the plug. I personally haven't experienced a collapsed lifter, but from my understanding it's a noticeable sound when it happens. When I had this issue it was due to needing plugs and wires. And I also put the updated gas pedal in.

ktuck · April 12, 2024

Thanks for the suggestions, Buck. No, I haven't researched the wiring to the coils, perhaps that could be the issue. Does that involve a check of reference voltage and ground continuity? I hear talk about checking the various ground points on the engine or frame...maybe that could be a factor? I haven't heard of the gas pedal deal, what's the issue with that? Thanks again.

newdude · April 12, 2024

11 hours ago, ktuck said:

I have a 2017 Silverado 1500 LT with a 5.3L with 114.000 miles that I bought from the original owner two years ago. I am sorry for the length of this post as I have tried to give the briefest but comprehensive analysis possible. I began noticing random misfires on occasions about 6 months ago but they have became more frequent and now are not intermittent anymore but constant. I currently have a steady CEL and codes P0300 and P219A. It shows up on light to moderate acceleration. I took it to a GM tech who suggested decarbonizing the engine. It made no difference at all, so he then suggested replacing the injectors. I did that myself to save a couple bucks and used GM injectors. In the last 6 months I have had two new sets of AC plugs in it and all the plug wires. I had a coil pack failure on cyl #1 so I replaced it and the misfire there went away. Erratic misfires began to start up again so I replaced all the other coil packs as well but the problem remained. The GM tech now thinks I have a collapsed lifter issue. I pulled both valve covers and inspected rockers, lifters and valve springs...no problems found. The inside of the engine looks pristine. There are no wobbly rockers and when spinning the engine over, all 16 valves appear to be opening consistent to all the others. Does not appear to have any wiped lobes or bent push rods. The original owner changed oil religiously at 3K intervals and I have followed that pattern myself. I drained the oil pan and looked for any traces of metal in the oil and found absolutely nothing. The oil is still very clean and clear and easy to see if contaminated. My scanner shows cylinders 2 and 5 as the chronic misfires I have switched plugs, wires and coil packs from good firing cylinders to see if the misfire will move to those cylinders but the misfires stay with 2 and 5. Since both are non-AFM cylinders, it kinda counters the GM techs theory of lifter problem, especially since visual inspection revealed nothing. Another data concern are the fuel trims. Bank 1 LTFT is around -15% and Bank 2 LTFT is around -28% which indicates a rich condition. I am puzzled that with the high negative LTFT, all the plugs are light colored almost white and certainly don't show a rich condition. Are the O2 sensors somehow being fooled? Their numbers look normal. The high fuel pressure is running around 480-600. The low fuel pressure jumps around while driving, I see it go as low as 25 and as high as 63...it never really holds steady very long, is that normal or possibly a sign of a fuel delivery issue? One more thing I'll throw out there, when it is missing and bucking on light load acceleration, if I kick it down and floor it, it takes off without any hesitation and runs strong and smooth. That seems kind of odd to me considering the multiple misfires. What am I overlooking here? I welcome any thoughts or ideas about this chronic misfire condition.

What p/n injectors did you use? Did you replace all 8?

ktuck · April 12, 2024

I used OEM injectors. They have GM part #, I don't remember what it was. I did replace all 8. It seemed to make sense to do so after going all that trouble.

ktuck · April 12, 2024

I found my receipt for the injectors, the GM number on them is 12668390. Since I think I have eliminated plugs, wires and coils by substitution, it may be worth going back in and switching some of the injectors around to see if that moves the misfire problem away from #2 or 5. I'm quite aware of the chance of getting a defective new part. I also am concerned with the wide variance in fuel pressure...could that be playing a part in this?

silveradosid · April 14, 2024

the negative fuel trims are an indication that there is to much oxygen in the exhaust, i would monitor the maf sensor and the o2 sensors. it is indicating that there is unmetered air getting in from somewhere, maybe an intake leak after the maf sensor.

Buckwild27 · April 16, 2024

On 4/12/2024 at 11:14 AM, ktuck said:

Thanks for the suggestions, Buck. No, I haven't researched the wiring to the coils, perhaps that could be the issue. Does that involve a check of reference voltage and ground continuity? I hear talk about checking the various ground points on the engine or frame...maybe that could be a factor? I haven't heard of the gas pedal deal, what's the issue with that? Thanks again.

Gm updated their gas pedal at some point in 2017, I'm unsure of exact time. It eliminates some of the pedal lag. Checking and cleaning all grounds is always a good plan. As far as the coil wires I would just start with a visual inspection for damaged wires.

rlcole321 · April 16, 2024

My two cents, I have a 2018 'Rado and my HP fuel pressure is a lot higher than that, in the 1,500 psi range and higher, may look into that. Have you told your GM tech about your low HP fuel range

ktuck · April 17, 2024

On 4/14/2024 at 9:18 AM, silveradosid said:

the negative fuel trims are an indication that there is to much oxygen in the exhaust, i would monitor the maf sensor and the o2 sensors. it is indicating that there is unmetered air getting in from somewhere, maybe an intake leak after the maf sensor.

My GM tech is telling me negative LTFT indicates a rich mixture, but he has been wrong about a couple other things I found out. Also, the spark plugs do not indicate a rich mixture, but more towards lean. The porcelains are very light tan, almost still white. He thinks my o2 sensors are being "fooled" into reporting a rich mixture and as a result the ECM is pulling back fuel...hmmm, does this make any sense?

ktuck · April 17, 2024

On 4/16/2024 at 1:36 PM, rlcole321 said:

My two cents, I have a 2018 'Rado and my HP fuel pressure is a lot higher than that, in the 1,500 psi range and higher, may look into that. Have you told your GM tech about your low HP fuel range

This is what my scanner is reporting to be my low side fuel pressure as I understand it. It is supposed run around 50 psi or so? I'm not real sure on that and haven't found the accurate spec for it yet. However, my scanner reads as low as 25 to as high as 63 psi. I don't think that is normal, is it?

Also, my scanner gives a readout for commanded fuel rail pressure of 580psi at idle and 580 at 2K. On the high fuel pressure side, my fuel rail pressure is running between 480-603 at idle and 574-602 at 2K. So, is it safe to assume that in reference to the commanded fuel rail pressure readings, mine are within range pretty much? The low side of course may be another story and I do not know if that wide range of variation is normal due to engine load, temperature or other sensor inputs.

ktuck · April 17, 2024

I am trying to figure out this problem I'm having methodically and accurately, and I must say, it has challenged my skillset greatly! To briefly restate, my primary issue is a constant misfire on cylinders 2 and 5, with an occasional misfire on #7 to a much lesser extent. All other cylinders firing off like clockwork. Two permanent codes persist, P0300 and P219A. The concerning data I am getting from my scanner is the very high negative long term fuel trims and questionable fuel pressure readings. I have read about various causes of high negative trim and they point to things like MAF, O2 sensors, leaky injectors, high fuel pressure and not enough air. I am inclined to focus on the two misfiring cylinders and consider causes that would isolate those two cylinders. For instance, if the MAF was defective, would it isolate just two cylinders and all others fire just fine? I don't think so. Same thing with high fuel pressure, or O2 sensors. Cylinders 2 and 5 are on opposite banks, if it were to be because of inaccurate O2 data, then there would have to be an O2 sensor on each bank that is bad in the same way...not too likely it seems to me. With that line of thinking, if that makes any sense at all, I feel like I should focus on an injector problem which most certainly could isolate one or more cylinders. It was about a month ago, I installed a new set of OEM injectors. As best as I recall, I have intermittent misfires prior to that, but not the consistent misfire on the two cylinders I have now. As many have said, there is no assurance that a new part couldn't be bad right out of the box. Also, and perhaps more likely, I may have done something during the installation of the injectors that brought this about even though I felt like I took great care and diligence when doing so. This is one time where I would not be too mad at myself if I find out I boogered up the job somehow, because at least then I would be able to finally put this problem behind me! Does this approach to the diagnosis at this point sound logically to all of you? I certainly welcome any other ideas I haven't considered yet.

newdude · April 17, 2024

6 minutes ago, ktuck said:

I am trying to figure out this problem I'm having methodically and accurately, and I must say, it has challenged my skillset greatly! To briefly restate, my primary issue is a constant misfire on cylinders 2 and 5, with an occasional misfire on #7 to a much lesser extent. All other cylinders firing off like clockwork. Two permanent codes persist, P0300 and P219A. The concerning data I am getting from my scanner is the very high negative long term fuel trims and questionable fuel pressure readings. I have read about various causes of high negative trim and they point to things like MAF, O2 sensors, leaky injectors, high fuel pressure and not enough air. I am inclined to focus on the two misfiring cylinders and consider causes that would isolate those two cylinders. For instance, if the MAF was defective, would it isolate just two cylinders and all others fire just fine? I don't think so. Same thing with high fuel pressure, or O2 sensors. Cylinders 2 and 5 are on opposite banks, if it were to be because of inaccurate O2 data, then there would have to be an O2 sensor on each bank that is bad in the same way...not too likely it seems to me. With that line of thinking, if that makes any sense at all, I feel like I should focus on an injector problem which most certainly could isolate one or more cylinders. It was about a month ago, I installed a new set of OEM injectors. As best as I recall, I have intermittent misfires prior to that, but not the consistent misfire on the two cylinders I have now. As many have said, there is no assurance that a new part couldn't be bad right out of the box. Also, and perhaps more likely, I may have done something during the installation of the injectors that brought this about even though I felt like I took great care and diligence when doing so. This is one time where I would not be too mad at myself if I find out I boogered up the job somehow, because at least then I would be able to finally put this problem behind me! Does this approach to the diagnosis at this point sound logically to all of you? I certainly welcome any other ideas I haven't considered yet.

I wonder if you've got 2 bad injectors. Going off the p/n you posted on your receipt, that # is a VERY old number. If you got some that were sitting around for some time, you could have a couple faulty injectors. If you got fresh ones when you bought those, you should have seen 12710481 (current #) or 12698484 or 12684125 (last 2 numbers GM used).

ktuck · April 17, 2024

2 hours ago, newdude said:

I wonder if you've got 2 bad injectors. Going off the p/n you posted on your receipt, that # is a VERY old number. If you got some that were sitting around for some time, you could have a couple faulty injectors. If you got fresh ones when you bought those, you should have seen 12710481 (current #) or 12698484 or 12684125 (last 2 numbers GM used).

Wow, that is good information to know, thanks newdude. That kinda makes me more inclined now to go ahead and redo the injectors, although the injectors I put in have the same GM part # as the original ones I took out. That is why I bought them, I assumed they were an exact match. Apparently, they have been upgraded since 2017. At this point, it would be worth it to purchase all new injectors with the current part # you listed and see what happens. Another reason I suspect injectors as the culprit is that when I floor it, it pulls fine with no hint of misfire. That makes me think the injectors, for whatever reason, are getting adequate fuel spray at higher speeds/load and at idle and light throttle driving not so much. Thanks again for enlightening me on those new part numbers.

newdude · April 18, 2024

14 hours ago, ktuck said:

Wow, that is good information to know, thanks newdude. That kinda makes me more inclined now to go ahead and redo the injectors, although the injectors I put in have the same GM part # as the original ones I took out. That is why I bought them, I assumed they were an exact match. Apparently, they have been upgraded since 2017. At this point, it would be worth it to purchase all new injectors with the current part # you listed and see what happens. Another reason I suspect injectors as the culprit is that when I floor it, it pulls fine with no hint of misfire. That makes me think the injectors, for whatever reason, are getting adequate fuel spray at higher speeds/load and at idle and light throttle driving not so much. Thanks again for enlightening me on those new part numbers.

Its not so much that they are "upgraded". The numbers can change just from changing supplier even. My thinking is you got old stock and could have 2 bad ones.