Cylinder Misfire (P0305 Cylinder 5)

Teufel Hunden

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Virginia
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2024 Ram TRX
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Marine Corps
Last week my check engine light came on and received the following error: P0305 Cylinder 5 Misfire. I dropped it off at the dealership and received a call later in the day stating that they can't replicate the issue and are chopping it up as a "fluke". Today, my check engine light came on again and I received that exact same error. This time after dropping it off at the dealership a different gentleman told me they are going to order a new fuel rail kit and also replace all the injectors. Hopefully this fixes the issue, I'll keep the forum updated.
 

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I had mine come on randomly, they did a PCM update supposedly and it hasn't come back.
 
IC coolant level changing at all?
Actually, when I dropped it off the first time they said that the coolant level was low and they topped it off. They also said they looked for leaks and didn't see any.
 
Actually, when I dropped it off the first time they said that the coolant level was low and they topped it off. They also said they looked for leaks and didn't see any.
Keep an eye on the coolant level. If it keeps dropping, it's probably in the cylinder
 
Actually, when I dropped it off the first time they said that the coolant level was low and they topped it off. They also said they looked for leaks and didn't see any.
Keep an eye on both coolant levels. I mark my tanks with a sharpie after sitting overnight.
 
Keep an eye on both coolant levels. I mark my tanks with a sharpie after sitting overnight.
How often are we supposed to top off coolant? I literally have them fill mine up from halfway between min/max every time I go in. It never goes too close or above the max line but they do pour new coolant in. Is that normal?
 
How often are we supposed to top off coolant? I literally have them fill mine up from halfway between min/max every time I go in. It never goes too close or above the max line but they do pour new coolant in. Is that normal?
Absolutely not normal. It's a closed system, so the only way to lose coolant is if there's a leak somewhere. If there's no evidence on the ground, or wetness around other components, then either the leak is so small that the coolant is evaporating/boiling off, or it's leaking internally and leaving through the exhaust.

Which tank is getting refilled regularly? The larger, main coolant tank, or the small intercooler tank?
 
How often are we supposed to top off coolant? I literally have them fill mine up from halfway between min/max every time I go in. It never goes too close or above the max line but they do pour new coolant in. Is that normal?
I top mine off about every 10k and I have to put in less and less each time. I don’t think it’s ideal but I have to do this with all my vehicles
 
Absolutely not normal. It's a closed system, so the only way to lose coolant is if there's a leak somewhere. If there's no evidence on the ground, or wetness around other components, then either the leak is so small that the coolant is evaporating/boiling off, or it's leaking internally and leaving through the exhaust.

Which tank is getting refilled regularly? The larger, main coolant tank, or the small intercooler tank?
larger main tank only. This is quite concerning. I don't smell it at all or out of the exhaust. I suspected an internal leak. Gonna check the components this weekend
 
How often are we supposed to top off coolant? I literally have them fill mine up from halfway between min/max every time I go in. It never goes too close or above the max line but they do pour new coolant in. Is that normal?
Only time I have added coolant in 3 years is when servicing either coolant system.
 
Absolutely not normal. It's a closed system, so the only way to lose coolant is if there's a leak somewhere. If there's no evidence on the ground, or wetness around other components, then either the leak is so small that the coolant is evaporating/boiling off, or it's leaking internally and leaving through the exhaust.

Which tank is getting refilled regularly? The larger, main coolant tank, or the small intercooler tank?
they said they vacuum tested it twice. and I will look for purple under the truck this weekend, what else should I tell them to look for?
 
larger main tank only. This is quite concerning. I don't smell it at all or out of the exhaust. I suspected an internal leak. Gonna check the components this weekend
Well, that's at least some good news. A leaking intercooler loop usually indicates a leaky supercharger brick, which could put enough coolant into your engine to hydrolock it (under extreme circumstances), which ain't good. The main tank dropping out is usually a small crack in the radiator side tanks, and is often slow enough that the coolant evaporates before it puddles anywhere. The only way for coolant to be making it into your cylinders from the main cooling loop is via a blown head gasket, which manifests all kinds of other symptoms as well. If they put tracer dye on the coolant, that should help to pinpoint it. If they didn't, they should.

The tough part about those kinds of radiator end tank leaks is they only happen under pressure, which normally means with HOT coolant, which lets it evaporate quickly enough that it doesn't puddle. If you have, or have access to, a radiator pressure tester, pump it up to 16psi or so and let it set overnight. That way, it's leaking cold, and has a better chance of creating a puddle that you can find.
 
Well, that's at least some good news. A leaking intercooler loop usually indicates a leaky supercharger brick, which could put enough coolant into your engine to hydrolock it (under extreme circumstances), which ain't good. The main tank dropping out is usually a small crack in the radiator side tanks, and is often slow enough that the coolant evaporates before it puddles anywhere. The only way for coolant to be making it into your cylinders from the main cooling loop is via a blown head gasket, which manifests all kinds of other symptoms as well. If they put tracer dye on the coolant, that should help to pinpoint it. If they didn't, they should.

The tough part about those kinds of radiator end tank leaks is they only happen under pressure, which normally means with HOT coolant, which lets it evaporate quickly enough that it doesn't puddle. If you have, or have access to, a radiator pressure tester, pump it up to 16psi or so and let it set overnight. That way, it's leaking cold, and has a better chance of creating a puddle that you can find.
just checked coolant levels on a flat surface after sitting for 24 hours. and it's exactly at min, about 60 something degrees outside
 
Well, that's at least some good news. A leaking intercooler loop usually indicates a leaky supercharger brick, which could put enough coolant into your engine to hydrolock it (under extreme circumstances), which ain't good. The main tank dropping out is usually a small crack in the radiator side tanks, and is often slow enough that the coolant evaporates before it puddles anywhere. The only way for coolant to be making it into your cylinders from the main cooling loop is via a blown head gasket, which manifests all kinds of other symptoms as well. If they put tracer dye on the coolant, that should help to pinpoint it. If they didn't, they should.

The tough part about those kinds of radiator end tank leaks is they only happen under pressure, which normally means with HOT coolant, which lets it evaporate quickly enough that it doesn't puddle. If you have, or have access to, a radiator pressure tester, pump it up to 16psi or so and let it set overnight. That way, it's leaking cold, and has a better chance of creating a puddle that you can find.
Remember the reason I asked about coolant levels was because of a misfire to start with. That is what I would expect to see if someone had a leaking head gasket or leaking IC brick.

If it’s under warranty I would go out and do some WOT pulls to see if you have any white smoke coming out. That’s just me.
 
Update; they replaced my fuel rail and injectors. Two days after that I received the same error P0305 Misfire. So, I went back to the dealership this morning and spoke to the service manager. This is the third time in one month I have taken the truck to the dealership for the same issue. Today, they called back and confirmed that coolant is getting into the cylinder. He stated that they are going to take the head off and see if there is a leaky gasket.
 
Update; they replaced my fuel rail and injectors. Two days after that I received the same error P0305 Misfire. So, I went back to the dealership this morning and spoke to the service manager. This is the third time in one month I have taken the truck to the dealership for the same issue. Today, they called back and confirmed that coolant is getting into the cylinder. He stated that they are going to take the head off and see if there is a leaky gasket.
Absolute idiots... a quick look with a borescope through the spark plug hole would have confirmed this the first time. No one does any kind of diagnosing/troubleshooting anymore. They just blindly follow what the trouble codes tell them, and fire the parts cannon at it.

Have you noticed a loss of coolant over time, by monitoring your reservoirs? With careful monitoring of the "at rest" coolant level, you can differentiate between a leaking head gasket (losing coolant from the main tank) vs. a leaky intercooler brick (losing coolant from the supercharger tank).
 
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