Rattle from engine when accelerating (sounds like keys)

[ShadowsPapa]

No fix yet. They have tried, octane booster which softened the noise for about 100miles, used higher octane gas (Shell), softened for about 50-100 miles, last time in (I think I am up to 6x now) they drained all the fuel from tank and refilled with new gas. They (dealership Tech) drove for about 50 miles and they said it was gone. After I picked up about 5 miles down the road it started back. When going about 26-27 on a sight incline just where your softly giving gas I can make it rattle for up to 10 sec nonstop. I have been waiting 2 weeks now for the next step. Supposedly Jeep Cares/Chrysler is going to send a field tech out to check it out. Chryster is calling it spark knock/detonation. Whatever it is, it is not normal and not expected from a 50k plus vehicle if you ask me. I know before someone throws this out there, the manual does say that certain fuel can cause a spark knock. I understand that, but this is not normal!

Punkinpudding1031, have you taken yours in for it??

That's exactly what it sounds like to me - detonation. (not sure where the "spark knock" moniker ever came from, there's technically no such thing - there's PRE-ignition or detonation, neither one caused by a spark!)
Your light acceleration under load (slight incline) at lower RPM sure sounds like detonation to me.
BUT - that's when the engine is also not sitting totally motionless and there's torque trying to twist things so they must check for a shield rattle, too. They happen under similar circumstances to detonation.

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[Punkinpuddin1031]

Yeah. It's the same sound. I was hoping it was something as simple as rocks in the heat shield, I will get it on the lift this weekend and see if I can narrow it down.

 

[bwm2020]

Does it sound like the noise from this video? https://www.jeepgladiatorforum.com/forum/threads/odd-engine-noise.37810/#post-611663

Kinda hard to tel but your description sounds like the same. The techs actually used a microphone mounted to the chassis/engine to try and record the noise. They were able to catch the peak rattle but it was hard to distinguish what what it is.
I took my gladiator in almost exactly 1yr ago and they still have no clue. Or at least they are not saying what it is. Seems they keep hoping these little fuel changes will fix. I think it is deeper than just the fuel.

 

[bwm2020]

That's exactly what it sounds like to me - detonation. (not sure where the "spark knock" moniker ever came from, there's technically no such thing - there's PRE-ignition or detonation, neither one caused by a spark!)
Your light acceleration under load (slight incline) at lower RPM sure sounds like detonation to me.
BUT - that's when the engine is also not sitting totally motionless and there's torque trying to twist things so they must check for a shield rattle, too. They happen under similar circumstances to detonation.

No shield or anything like that rattling. That has been checked out by me and the techs.

 

[ShadowsPapa]

No shield or anything like that rattling. That has been checked out by me and the techs.

OK - I just didn't want you to go through what a buddy of mine did in college. He kept complaining of a rattle in his fairly new Chevy Luv pickup (if you can call those a pickup HAHA)
He had it to a dealership, to another shop and he himself was a decent mechanic. I was sitting in his truck as he drove us to the local - uh, well, eating place for lunch and he told me of that noise in his truck. My hearing was ok back then...... and I heard it.
I asked him to stop, I got out, reached up under the seat to find an empty pop can rollig around on the springs up under the seat.

Anyway, your description does indeed sound like detonation. In fact it's a classic description on how to make it happen if it's going to.
What temperature is the engine when this is happening? Heat is a huge contributing factor. Anything that causes it to run hot, or poor coolant circulation, whatever, can contribute to it.
I was reading a technical document from one of the fuel companies last night about octane in modern fuels and oddly enough, they said higher than recommended octane can cause the "computer" to set up conditions for detonation and they had seen cases where higher octane fuel actually contributed, not helped. I have to find that again because it goes against everything in my very being and training - but then, my experience is 1994 and older.
Maybe I read it wrong and it was about midnight and I was nodding off so who knows.......
True detonation is where the normal spark ignites the charge, the burn begines and the flame front progresses across the chamber - the front acting almost like a wall, pressure bulding in the chamber forces unburned charge "into a corner" and compresses it until the heat of compression sets it off - then you have a second flame front advancing toward the first. The collision normally sets off literally a sonic boom that reverberates in the block causing the "ping" sound.
Higher octane fuel RESISTS SELF-IGNITION. That's it, same BTU content, same burn RATE, but it resists self-ignition. That's due to longer more complex molecules.
I've put together several papers and did a lot of study on it years ago when deciding to get into higher compression performance engines. OF course back then we dealt with quench, turbulance of the entering mixture and other means to prevent detonation. For the AMC 390 a special cut into the head was found to prevent it. At higher RPM there isn't TIME for self-ignition.
It normally happens at moderate RPMs. The burn is literally a burn process that takes time. Not an instant explosion.

 

[bwm2020]

OK - I just didn't want you to go through what a buddy of mine did in college. He kept complaining of a rattle in his fairly new Chevy Luv pickup (if you can call those a pickup HAHA)
He had it to a dealership, to another shop and he himself was a decent mechanic. I was sitting in his truck as he drove us to the local - uh, well, eating place for lunch and he told me of that noise in his truck. My hearing was ok back then...... and I heard it.
I asked him to stop, I got out, reached up under the seat to find an empty pop can rollig around on the springs up under the seat.

Anyway, your description does indeed sound like detonation. In fact it's a classic description on how to make it happen if it's going to.
What temperature is the engine when this is happening? Heat is a huge contributing factor. Anything that causes it to run hot, or poor coolant circulation, whatever, can contribute to it.
I was reading a technical document from one of the fuel companies last night about octane in modern fuels and oddly enough, they said higher than recommended octane can cause the "computer" to set up conditions for detonation and they had seen cases where higher octane fuel actually contributed, not helped. I have to find that again because it goes against everything in my very being and training - but then, my experience is 1994 and older.
Maybe I read it wrong and it was about midnight and I was nodding off so who knows.......
True detonation is where the normal spark ignites the charge, the burn begines and the flame front progresses across the chamber - the front acting almost like a wall, pressure bulding in the chamber forces unburned charge "into a corner" and compresses it until the heat of compression sets it off - then you have a second flame front advancing toward the first. The collision normally sets off literally a sonic boom that reverberates in the block causing the "ping" sound.
Higher octane fuel RESISTS SELF-IGNITION. That's it, same BTU content, same burn RATE, but it resists self-ignition. That's due to longer more complex molecules.
I've put together several papers and did a lot of study on it years ago when deciding to get into higher compression performance engines. OF course back then we dealt with quench, turbulance of the entering mixture and other means to prevent detonation. For the AMC 390 a special cut into the head was found to prevent it. At higher RPM there isn't TIME for self-ignition.
It normally happens at moderate RPMs. The burn is literally a burn process that takes time. Not an instant explosion.

Temp is normal and usually after about a 2 mile runs after startup I can mimic noise anytime.

 

[Moe_Fugga]

I’m with ShadowsPapa. Sounds like detonation issues or “spark knock”. Like marbles in a tin can. Techs should look for a fix before they have to replace the engine....

https://dannysengineportal.com/engine-spark-knock-that-annoying-knocking-pinging-or-rattling-sound/

 

[bwm2020]

I’m with ShadowsPapa. Sounds like detonation issues or “spark knock”. Like marbles in a tin can. Techs should look for a fix before they have to replace the engine....

https://dannysengineportal.com/engine-spark-knock-that-annoying-knocking-pinging-or-rattling-sound/

That what I keep waiting on. I have put 22k miles on it since I 1st complained to Jeep about it. At this rate it will 60k miles before they figure this out.

 

[iGlad]

OK - I just didn't want you to go through what a buddy of mine did in college. He kept complaining of a rattle in his fairly new Chevy Luv pickup (if you can call those a pickup HAHA)
He had it to a dealership, to another shop and he himself was a decent mechanic. I was sitting in his truck as he drove us to the local - uh, well, eating place for lunch and he told me of that noise in his truck. My hearing was ok back then...... and I heard it.
I asked him to stop, I got out, reached up under the seat to find an empty pop can rollig around on the springs up under the seat.

Anyway, your description does indeed sound like detonation. In fact it's a classic description on how to make it happen if it's going to.
What temperature is the engine when this is happening? Heat is a huge contributing factor. Anything that causes it to run hot, or poor coolant circulation, whatever, can contribute to it.
I was reading a technical document from one of the fuel companies last night about octane in modern fuels and oddly enough, they said higher than recommended octane can cause the "computer" to set up conditions for detonation and they had seen cases where higher octane fuel actually contributed, not helped. I have to find that again because it goes against everything in my very being and training - but then, my experience is 1994 and older.
Maybe I read it wrong and it was about midnight and I was nodding off so who knows.......
True detonation is where the normal spark ignites the charge, the burn begines and the flame front progresses across the chamber - the front acting almost like a wall, pressure bulding in the chamber forces unburned charge "into a corner" and compresses it until the heat of compression sets it off - then you have a second flame front advancing toward the first. The collision normally sets off literally a sonic boom that reverberates in the block causing the "ping" sound.
Higher octane fuel RESISTS SELF-IGNITION. That's it, same BTU content, same burn RATE, but it resists self-ignition. That's due to longer more complex molecules.
I've put together several papers and did a lot of study on it years ago when deciding to get into higher compression performance engines. OF course back then we dealt with quench, turbulance of the entering mixture and other means to prevent detonation. For the AMC 390 a special cut into the head was found to prevent it. At higher RPM there isn't TIME for self-ignition.
It normally happens at moderate RPMs. The burn is literally a burn process that takes time. Not an instant explosion.

I appreciate the break down on this. Is this noise a “normal” thing caused by detonation?

I’m with ShadowsPapa. Sounds like detonation issues or “spark knock”. Like marbles in a tin can. Techs should look for a fix before they have to replace the engine....

https://dannysengineportal.com/engine-spark-knock-that-annoying-knocking-pinging-or-rattling-sound/

I better get my trucks noise logged before it too late then.

That what I keep waiting on. I have put 22k miles on it since I 1st complained to Jeep about it. At this rate it will 60k miles before they figure this out.

How much time has the truck been in the dealers possession as they have been troubleshooting this problem?

 

[bwm2020]

I appreciate the break down on this. Is this noise a “normal” thing caused by detonation?




I better get my trucks noise logged before it too late then.



How much time has the truck been in the dealers possession as they have been troubleshooting this problem?

Probably 4-5 weeks or more since last Dec ‘19. Been waiting since Nov 23 for what Chrysler’s next step will be. Said they are sending a field tech out. Guess they can’t find one. Very frustrating!!!

 

[19Comanche86]

I’m having the exact same noise. Definitely more noticeable on cold starts. It 100% sounds like detonation, as soon as I heard it on my truck that’s what I thought right away.

 

[ShadowsPapa]

I appreciate the break down on this. Is this noise a “normal” thing caused by detonation?




I better get my trucks noise logged before it too late then.



How much time has the truck been in the dealers possession as they have been troubleshooting this problem?

The noise is caused by detonation - which is NOT normal. Not all detonation results in an audible sound like the "ping" or "rattle" but normally it does.

Detonation is not normal and should never be allowed.
The sound is a normal sign of detonation, if that makes sense.

The shock wave of the two flame fronts colliding blows away the cooler boundary layer above the piston exposing the piston head to temperatures that can melt the piston. The shock waves can also result in - - >

 

[bwm2020]

I’m having the exact same noise. Definitely more noticeable on cold starts. It 100% sounds like detonation, as soon as I heard it on my truck that’s what I thought right away.

Funny, I see and hear of this more and more and they say that mine is the only one. Guess we all need to start making more noise about it! Lol

 

[bwm2020]

The noise is caused by detonation - which is NOT normal. Not all detonation results in an audible sound like the "ping" or "rattle" but normally it does.

Detonation is not normal and should never be allowed.
The sound is a normal sign of detonation, if that makes sense.

The shock wave of the two flame fronts colliding blows away the cooler boundary layer above the piston exposing the piston head to temperatures that can melt the piston. The shock waves can also result in - - >

that’s why I’m trying to get them to figure it out. It is not normal! I would hate to just deal with it and never report it then 20-30k mile down the road have engine problem. Shouldn’t be happening. Thanks for all the detailed explanation of spark knock/detonation.

 

[Moe_Fugga]

that’s why I’m trying to get them to figure it out. It is not normal! I would hate to just deal with it and never report it then 20-30k mile down the road have engine problem. Shouldn’t be happening. Thanks for all the detailed explanation of spark knock/detonation.

There are several videos on YouTube of the noise on film. Post up your phone, or a good camera, in the cab and try to record it. Obviously no radio or talking and try to hit your light (lugging) acceleration pattern that causes it several times before you stop the recordnig. I would even go as far as to walk around the vehicle beforehand with the camera to set the foundation that the vehicle in the video is actally yours. Take the video to stealership service and show them. Then it is documented. If they don't fix it and the engine goes out you will have a solid case. Hell, I would even film my interaction with the stealership. I loathe dealing with stealerships. Good Luck

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