Two engines, two misfires and their diagnoses

[The_Eric]

About two weeks ago I had a guy unexpectedly drop his 13 Ram 2500 5.7 - he said that it was feeling a little punky and the engine light would come on and flash. Eventually I brought it in and scanned it - misfire on 5. Road test showed that under light load it would drive okay but using the skinny pedal with much enthusiasm would bring about a misfire and flashing light. After too much of that the injector and coil for 5 would just shut off. After that I ran a relative compression test on it.. results as follows below.

Fast forward to yesterday - another guy shows up with a 2016 GMC Sierra with a 6.2. Only had a P0300, but data showed that #4 was dead. Said that it started running rough and had a flashing engine light. He continued to drive it around, got more gas and added a bunch of fuel system cleaner. Went to a friends house and chilled there for a while and when he got back in, he claimed that it ran perfectly only for it to resume the same thing the next day. For kicks, I checked spark which it had. I pulled the plug and it was SOAKED! I blew it out and put it in the bead blast cabinet so I could inspect the insulator for cracks. I did find 2 little black marks that I could catch the pick in. Figuring that it was a failure of the insulator and that voltage was leaking out there, I put a plug in it. Nope.. Still 100% dead. Brought it in and did relative compression on it too...


The 6.2 is on top and the Hemi on the bottom. Also the red trace is the inverted coil current draw to mark #5. I'm curious what you guys think. The Hemi is going to get a remanned motor and the 6.2 isn't going to be my problem.

 

[The_Eric]

Here's a little more info on the Hemi - after the relative compression test and seeing that #5 had a higher current draw than the rest,I pulled the valve cover for inspection and found this - and it's because of this and the fact it's got 180k on it that it's going to get a remanned engine.

 

[Timmastertech]

RC is my first test on any misfire diagnosis and I preach that whenever I teach a misfire, scope, driveability or no start class. It is probably one of the fastest tests you can perform to easily gain diagnostic direction. I have a laptop turned on on my toolbox all day and my scope stuff within arms reach. Half the time if I pull a car in and feel a misfire I will do that before I even scan for codes.

 

[OVERKILL]

That's very similar to the mileage at which our 2010/2011's lost a lifter, so I'm not surprised. This engine (2013) would be right within that peak lifter failure era.

 

[The_Eric]

RC is my first test on any misfire diagnosis and I preach that whenever I teach a misfire, scope, driveability or no start class. It is probably one of the fastest tests you can perform to easily gain diagnostic direction. I have a laptop turned on on my toolbox all day and my scope stuff within arms reach. Half the time if I pull a car in and feel a misfire I will do that before I even scan for codes.

Yeah I need to make it an arbitrary part of my diag routine. The majority of my misfire cases are pretty obviously ignition, but you're 100% right that it's just a good idea and quickly shows the mechanical heath of all cylinders relative to one another.

 

[The_Eric]

That's very similar to the mileage at which our 2010/2011's lost a lifter, so I'm not surprised. This engine (2013) would be right within that peak lifter failure era.

Honestly I'm surprised it lasted this long - he's not the best at oil changes. He does construction, so he's driving every day.

 

[OVERKILL]

Honestly I'm surprised it lasted this long - he's not the best at oil changes. He does construction, so he's driving every day.

At least with ours, it didn't seem to matter how they were driven (and they were on bulk Valvoline/NAPA 5W-20 which left a nice bit of varnish even at reasonably short intervals) or how frequently the oil was changed, they all seemed to experience this at around the 190-200k mile mark. We also lost a 2014 (it has a new engine), the 2016 is still going.

 

[The_Eric]

At least with ours, it didn't seem to matter how they were driven (and they were on bulk Valvoline/NAPA 5W-20 which left a nice bit of varnish even at reasonably short intervals) or how frequently the oil was changed, they all seemed to experience this at around the 190-200k mile mark. We also lost a 2014 (it has a new engine), the 2016 is still going.

Do you have any insight on the cause? Metallurgy issues? Can I assume that they've got them pretty well sorted? I'm going to push for a Chrysler reman (who knows who does it for them) just because I feel like they'll have the least issues of the various companies out there.

 

[OVERKILL]

Do you have any insight on the cause? Metallurgy issues? Can I assume that they've got them pretty well sorted? I'm going to push for a Chrysler reman (who knows who does it for them) just because I feel like they'll have the least issues of the various companies out there.

Yeah, metallurgical issues with the roller/pin/needles. Member Teamzero, who is an FCA tech did a bit of a deep dive on them and found that the needles eventually breached the surface hardening on the pin, which then resulted in them slowly creating a ditch and once that ditch got deep enough, a needle gets stuck in it, others pile up behind it, the roller stops rolling and the seized roller then destroys the cam lobe.

There were a few different part #'s from 2010+, but in 2018 there was an updated design, made in Germany, with much larger needles, which is supposed to cure the issue, though I do believe there have still been a few instances of failure reported. Both of mine should have the updated lifters, so I'm hoping they are problem-free.

I do lament their use of a SADI camshaft however. GM uses steel billets, which is why the cam often survives a lifter failure (and GM has a higher rates of lifter failure, because they not only have the same roller issue, but also the failure of the AFM/DFM lifters themselves) while with FCA/Stellantis, the cam isn't going to survive, as the seized roller very quickly breaks through the surface hardening and then chews away at the soft iron.

 

[The_Eric]

Yeah, metallurgical issues with the roller/pin/needles. Member Teamzero, who is an FCA tech did a bit of a deep dive on them and found that the needles eventually breached the surface hardening on the pin, which then resulted in them slowly creating a ditch and once that ditch got deep enough, a needle gets stuck in it, others pile up behind it, the roller stops rolling and the seized roller then destroys the cam lobe.

There were a few different part #'s from 2010+, but in 2018 there was an updated design, made in Germany, with much larger needles, which is supposed to cure the issue, though I do believe there have still been a few instances of failure reported. Both of mine should have the updated lifters, so I'm hoping they are problem-free.

I do lament their use of a SADI camshaft however. GM uses steel billets, which is why the cam often survives a lifter failure (and GM has a higher rates of lifter failure, because they not only have the same roller issue, but also the failure of the AFM/DFM lifters themselves) while with FCA/Stellantis, the cam isn't going to survive, as the seized roller very quickly breaks through the surface hardening and then chews away at the soft iron.

Thank you for the insight. That's the problem with being a small one man band type shop that primarily works on older vehicles (believe it or not, a 2013 is on the newer side of what I work on) - I don't have the exposure or time to dig into these issues. I know that they exist but often the root cause isn't something that I'm up on.