Engine losses power in hot days

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Xzena3

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I have a 2014 Ram 2500 5.7L with 4.10 gears and 150k miles. At the beginning of last summer I started getting a loss of engine power after sitting in heavy traffic for an hour or more with ambient temperature at or above 90 degrees. The condition doesn't feel like a dead miss but rather like the engine is de rated. When I hit the throttle and hold it at let's say 1/4 there is a noticeable lack of power. If I stay on it after a few seconds it comes to life and feels normal. I have tried manually shifting and there is no change. Once the condition comes in it will stay that way for several days of driving with no traffic before it clears up. I have disconnected the battery and it seems to make a big difference but the next time I am stuck in traffic it returns again. I replaced the plugs at 100k and perform all required maintenance. There are no codes and it does not happen in cold weather (no issues in the NE winter). I was thinking maybe a weak coil pack but I don't have any misfire codes to support that. Any ideas on what to check?
Thanks in advance
 

bluebeast1562

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Sorry mate, cannot help you. Should post to the 4th Gen section to see if anyone else in the generation has had the issue.
 

ramffml

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You running 87 or 89 octane? I thought more than once I felt a similar thing, but generally when I'm hitting 2000+ rpms (climbing a hill or passing someone) and much more noticable on hot, humid days with 87. Never noticed it in winter either. I switched back to 89/91 for towing and I swear my truck runs better but I hate to put too much weight on what I think I feel.

All I can say is, if you're running 87 try bumping up the octane.
 
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Xzena3

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Thanks. I do run 87, I never noticed enough of an improvement when it is running right to justify the cost but I will give it a try.
 

ramffml

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Thanks. I do run 87, I never noticed enough of an improvement when it is running right to justify the cost but I will give it a try.

As costly as it might seem for a test, I'd fill up at least twice with 91 (if you can afford it) before forming an opinion on whether it's helping, just because you have left over fuel in the tank that's 87 so mixing (for example) 89 with a quarter tank of 87 is still going to drag you down to 87-88. If you put in 91 then it will down mix to 89ish for the first tank etc.

Technically we should see no difference with 89 vs 91, but again that's in a perfect world with no 87 in the mix/tank or in the hose from the previous guy etc.

I plan to throw a bottle of seafoam in my next tank as well.
 

Hookedup87

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I believe our Hemi engines suffer a lot from heat soak, and from what I understand, the computer begins pulling timing out under those conditions which would definitely result in a feeling of lost power. These engines are programmed to run very hot for both emissions and fuel economy purposes.
 

Burla

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My trucks runs like a dog with 87 and runs like a rap-ed ape with 91.

Anyhow, more molecules = more energy and cold air has more o2. Cold air is denser so it has more o2, not as a % as in you get more other molecules as well, but more o2. You can try a cai as well.
 

seabrook

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My trucks runs like a dog with 87 and runs like a rap-ed ape with 91.

Anyhow, more molecules = more energy and cold air has more o2. Cold air is denser so it has more o2, not as a % as in you get more other molecules as well, but more o2. You can try a cai as well.
yep mine too but i pay very close attention to how my truck runs
 

Dirty D

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100% i almost never put 87 in my truck, even before i got it tuned and some mods. i do notice a massive diff in quality depending on where i get it from as well. if i hit up the sonoco pump and grab their 91 vs Shells 91 lol world of difference there as well.
 

GTyankee

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Could this be causing your engine to run like crap

 

Jebb

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I believe our Hemi engines suffer a lot from heat soak, and from what I understand, the computer begins pulling timing out under those conditions which would definitely result in a feeling of lost power. These engines are programmed to run very hot for both emissions and fuel economy purposes.
^+1
Long term fuel trim is probably kicking in as well and leaning out A/F due to the combination of hot weather and extended idling. You might be able to test that by disconnecting the battery for a bit then re-connecting and driving.
 
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Xzena3

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I have disconnected the battery after experiencing the issue and it definitely makes a noticeable difference. It is such a dog after running in these conditions. Hoping the higher octane helps.
 

crazykid1994

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Possibility of a faulty intake air temp sensor? May need to watch live data. Curious if it didn’t get heat soaked real bad or another sensor got to hot and is faulty. Especially if sitting at idle with extreme heat outside anything is possible. Could even be fuel pump. Live data will show fuel pressure and you can watch to make sure it’s close to 60psi. I think mine goes from 57-59psi. If the pump is not reacting fast enough to build pressure it could cause issues.
 
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Xzena3

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I was actually thinking along the same lines with a sensor issue or possibly a weak coil pack but I don't get any misfire codes. I can't see the knock sensors with my scanner and I was thinking maybe one of them was malfunctioning with the heat. Unfortunately none of it makes sense because if I disconnect the battery for a few minutes it makes a huge difference in performance. I will have to do some more investigating.
Thanks
 

Dusty

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My one son had a similar complaint with his 2017 Ram 1500. He has buddies that tech. for an auto repair business and one of them suggested a "full fuel service," which included cleaning the intake manifold. The fuel service fixed it, according to my son.

The 5.7s have a gate or door that switches from short runner to long runner depending on select engine conditions. His tech. friend told him that those gates get sticky from poor fuel quality. There's a motor that drives the gate movement, but a quick check in the service manual and I can't find a trouble code for it.

Regards,
Dusty
2019 Ram 1500 Billet Silver Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33-gallon fuel tank, factory dual exhaust, 18” wheels. Build date: 3 June 2018. Now at 73071 miles
 

CrasherAsher

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I do notice a difference between 87 to 91 octane as far as driving in the heat (100 to 112 degrees) there is a loss of power compared to cold weather. but nothing like you are describing. my truck still gets off the line just fine no matter if i have been idling a long time. my humble opinion i dont think its the hot weather.
 
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Xzena3

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It definitely has something to do with ambient temperature but I don't think it's the fuel. I filled up with super and although I know I will have to run at least another tank through the system I don't see any difference in performance. It has not been above 90 and I have not sat in traffic yet but I am not holding my breath.
 

Wild one

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It definitely has something to do with ambient temperature but I don't think it's the fuel. I filled up with super and although I know I will have to run at least another tank through the system I don't see any difference in performance. It has not been above 90 and I have not sat in traffic yet but I am not holding my breath.
Odds are you have the insulated engine cover,you could try removing it,and see if taking it off helps,might not do anything,but it only takes a minute to pull it off to check if it might be heat soaking your intake manifold
 

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