Engine knocking

[wvinson]

I noticed my Limited Hemi knocking on hard accelerating even when I'm not towing. Anyone else have this issue?
Using regular octane fuel as I used in my '14 and '17 sport with no issues.

 

[41magmag41]

I thing if you read your manual you will find 89 octane is recommended. try a couple of tanks full and it will go away.

 

[wvinson]

So why did my 14 and 17 with the same engine run perfectly with 87 octane?

 

[Rob5589]

The manual recommends 89 but also states 87 is acceptable. I have even run 85 in mine with no audible knock. Not recommend, just fyi.

 

[Zeronet]

I noticed my Limited Hemi knocking on hard accelerating even when I'm not towing. Anyone else have this issue?
Using regular octane fuel as I used in my '14 and '17 sport with no issues.

Have you experienced the knock on multiple tanks of fuel? Maybe some bad gas? If you always fill at the same gas station try a different one?

I’d try a full tank of 89 octane to see if that reduces/eliminates the knock.

I use 87 most of the time when not towing. No knock here.

 

[Konrad]

So why did my 14 and 17 with the same engine run perfectly with 87 octane?

Even if it's the same engine from mechanical standpoint, the ECU is probably programmed differently, what with the EPA / fuel efficiency / eco friendly friendly nonsense. Different timing advance, shift points etc.


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[Jkurtz]

I noticed my Limited Hemi knocking on hard accelerating even when I'm not towing. Anyone else have this issue?
Using regular octane fuel as I used in my '14 and '17 sport with no issues.

I have a 19 Laramie Longhorn with the Hemi. I had a problem with a knocking sound at certain rpm’s. Dealer was great but it took a long time and many visits to locate the real problem. Turned out to be bad lifters. They were replaced and it runs great now. I just wanted to share because my issue was difficult to diagnose. If yours keeps having this problem, it might be mentioned to your service advisor so this can be checked.

 

[wvinson]

Have you experienced the knock on multiple tanks of fuel? Maybe some bad gas? If you always fill at the same gas station try a different one?

I’d try a full tank of 89 octane to see if that reduces/eliminates the knock.

I use 87 most of the time when not towing. No knock here.

I thought about that but I get gas at many different locations. It knocks even when it downshifts to pass or accelerating more than normal when not towing anything.

 

[wvinson]

I have a 19 Laramie Longhorn with the Hemi. I had a problem with a knocking sound at certain rpm’s. Dealer was great but it took a long time and many visits to locate the real problem. Turned out to be bad lifters. They were replaced and it runs great now. I just wanted to share because my issue was difficult to diagnose. If yours keeps having this problem, it might be mentioned to your service advisor so this can be checked.

Thanks for the info. I'll mention that at my service visit this week. What octane do you use when you heard the knocking?

 

[rlc2020]

How many miles and what oil is in it? It's NOT the fuel. I switched from 89 to 87 8,000 miles ago and have had zero issues with knock. 87 is not the culprit. But, my truck had noisy lifters with the factory break-in oil in it. I did an oil change at 2k miles and then again at 4k miles and it went away completely. If the truck is still on the factory oil, get it out of there.

 

[RamGuy32]

So why did my 14 and 17 with the same engine run perfectly with 87 octane?

There are lots of variables but the biggest one is the tune. The engine is tuned different and while it can adapt to lower octane, that adaptation brings on with it the engine ping. It's not harmful unless you're seeing a lot of knock. In that case, it could be where you're fueling up. Run it dry and then try a good tank of Chevron and use a high use station so you know the fuel is fresh. If that's the case, it's the station and that happens.

 

[wvinson]

How many miles and what oil is in it? It's NOT the fuel. I switched from 89 to 87 8,000 miles ago and have had zero issues with knock. 87 is not the culprit. But, my truck had noisy lifters with the factory break-in oil in it. I did an oil change at 2k miles and then again at 4k miles and it went away completely. If the truck is still on the factory oil, get it out of there.

it has 5k miles on it -- noticed it a couple of months ago. What would the engine pinging have to do with the oil?

 

[wvinson]

There are lots of variables but the biggest one is the tune. The engine is tuned different and while it can adapt to lower octane, that adaptation brings on with it the engine ping. It's not harmful unless you're seeing a lot of knock. In that case, it could be where you're fueling up. Run it dry and then try a good tank of Chevron and use a high use station so you know the fuel is fresh. If that's the case, it's the station and that happens.

I usually fuel up at high use stations so I don't think gas is the problem. Usually the engine computer will adjust.

 

[airgas1998]

it has 5k miles on it -- noticed it a couple of months ago. What would the engine pinging have to do with the oil?

yilch...

 

[rlc2020]

are you sure it's pinging and not lifter noise? they can sound similar at high rpm. obviously oil would not cause pinging, but it can cause lifter clatter...

 

[Willwork4truck]

Maybe avoid gas stations with the garden hose going down into the tank?
Seriously, look into that valves post, #7.
I’d hate to think that they would be the cause but if you’ve eliminated fuel quality then start looking at timing or the reported valves.
Dealer service may be able to help since its warranty still.

 

[wvinson]

are you sure it's pinging and not lifter noise? they can sound similar at high rpm. obviously oil would not cause pinging, but it can cause lifter clatter...

It's not lifter clatter, just pinging. Sometimes I get the lifter clatter like lots of other members here upon startup.

 

[Jkurtz]

Thanks for the info. I'll mention that at my service visit this week. What octane do you use when you heard the knocking?

It didn’t matter what octane. Tried them all and still had the problem. Kept getting worse over time.