Rattle from engine when accelerating (sounds like keys)

[ShadowsPapa]

Haha, isn't that the kicker, trying to describe a sound with written word. I'm not sure that the detonation is problematic intrinsically, sometimes it just happens on occasion and I'm sure it varies among all the different engines of the world.

However, I don't really know much about the affects of detonation over years and years of driving, I'd like to keep my truck for a very long time. Seems like combustion happening outside the chamber can put a lot of added stress on head gaskets and other engine parts not designed to be exposed to it. If this engine is designed to handle detonations outside the combustion chamber, then no- I doubt its problematic. Detonation is inefficient, and causes additional stress. I'd like to think that engineers would like to reduce both of those things over the life of a product. Haha but what do I know?

If we're unable to determine that its not to be worried about, or that it can't be fixed, I can think of 392 cubic reasons to just replace the whole thing.

Combustion, normal or not, detonation or preignition - is IN the combustion chamber.

Pre-ignition is when the charge is lit by something - pressure, heat, an ember, etc. before the spark, but it still is in the normal combustion chamber. It rattles because the charge is already burning, a flame front advances then a spark ignites the rest of the charge when it SHOULD be lit - and the two flame fronts collide - a sonic boom of sorts resonates in the block.

Detonation happens AFTER the normal spark - the advancing flame front from the normally burning charge compresses the unburned gases into a corner, so to speak - compressing it above normal range and creating heat in the process until the unburned part of the charge ignites - and another flame front approaches the normal one - boom - you get that ping or rattle.

What happens with detonation is that the colliding flame fronts blow the boundary layer off the top of the piston exposing it to the entire heat of combustion. Normally there's a very thin layer, the boundary layer, of the fuel charge that isn't burned. It serves as an insulation against the heat of combustion which is above the temperature at which the piston may melt. It also is more of an explosion instead of a calculated steady burn - which can literally BREAK things if it's severe enough.
Engines can survive periodic detonation. It's when it's loud, severe, and fairly steady, not "just occasional" that it does damage.
In any case, it all happens in the combustion chamber where the charge is normally burned.

I've got pages of stuff I've written and collected and examples, numbers, temperatures, etc. but won't get into that.

Good quench, swirl, turbulence, fast burn chamber design, all are ways to prevent detonation.

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[flipmode]

Thanks for writing that out, very informative. I was confusing location and timing, this clears that up.

 

[jmdwifi]

Did anyone get a resolution to this? I have 29k on mine and usually I have the radio on, so I don't know how long it's done it. I had the doors off a few weeks ago and my wife was with me, so no radio (I like my wife and talk to her when we ride together) I noticed mine pings when rounding corners at low speeds. I wonder if the transmission isn't downshifting enough or the timing is off. I hate this kind of shit. I am sure the dealer will say it's normal or they can't hear it. I know what pre-detonation sounds like and this is what it is.

 

[ShadowsPapa]

. I know what pre-detonation sounds like and this is what it is.

mmmmm, apparently not ;-) because there's no such thing as "pre-detonation".
I've outlined what they are and what the differences are several times in this thread and in others.

PREIGNITION is when something ignites the fuel BEFORE the normal spark ignites it.
That "something" can be a hot ember, carbon, overly high compression, etc. but preignition is when the charge is lit too early and the advancing flame front from THAT fire hits the flame front from the later-lit normally burning charge and the "boom" resonates in the block.

DETONATION is when the normal advancing flame front heats and compresses the unburned fuel enough it self-ignites.
It's where the unburned fuel is literally pushed harder and harder into a "corner" which causes heat because compressing a gas heats it and the fuel can't resist self-igniting.
The flame front from that burn collides with the normally advancing flame from from the normal burn and boom.
It's one or the other, not both.

What happens with detonation is that sometimes under certain conditions or where it's severe enough (loud enough, constant enough) the collision literally blows the protective layer of unburned charge (the boundary layer) away from the top of the piston exposing it to temperatures high enough to melt aluminum (and the extreme pressure all at once can also break off the edges of the top of the piston, besides causing it to melt)
It also often cracks spark plug porcelain which can lead to a misfire.

Some detonation is not going to hurt anything. Even in the 70s they were saying some mild detonation on occasion is fine.
I've driven/owned vehicles that had mild detonation and those that had none. My last 390 had some detonation at times - especially in hot weather, but it wasn't destructive (I also changed from the stock type pistons and closed up the quench so it was less severe and less damaging). The current owner is doing fine with it.

I have not heard the ping yours is making so I can't say if it's severe, trouble or not, or something to not worry about. If that's the only time it does it - it's likely not a huge thing. Yes, SOME can be normal. Mine has NO PING. Top on, off, whatever, and when my wife is with me the radio is off (she doesn't care for my music and I can't stand whiney grating country music so it's none when we are both in there)
As far as yours "not downshifting" I don't know what sort of throttle pressure you drive with - if maybe 1/16" more of push would kick it down and get out of the lugging range or not but if it's going to ping due to detonation, that's the exact circumstances I'd expect any engine to do it in.

 

[jmdwifi]

mmmmm, apparently not ;-) because there's no such thing as "pre-detonation".
I've outlined what they are and what the differences are several times in this thread and in others.

PREIGNITION is when something ignites the fuel BEFORE the normal spark ignites it.
That "something" can be a hot ember, carbon, overly high compression, etc. but preignition is when the charge is lit too early and the advancing flame front from THAT fire hits the flame front from the later-lit normally burning charge and the "boom" resonates in the block.

DETONATION is when the normal advancing flame front heats and compresses the unburned fuel enough it self-ignites.
It's where the unburned fuel is literally pushed harder and harder into a "corner" which causes heat because compressing a gas heats it and the fuel can't resist self-igniting.
The flame front from that burn collides with the normally advancing flame from from the normal burn and boom.
It's one or the other, not both.

What happens with detonation is that sometimes under certain conditions or where it's severe enough (loud enough, constant enough) the collision literally blows the protective layer of unburned charge (the boundary layer) away from the top of the piston exposing it to temperatures high enough to melt aluminum (and the extreme pressure all at once can also break off the edges of the top of the piston, besides causing it to melt)
It also often cracks spark plug porcelain which can lead to a misfire.

Some detonation is not going to hurt anything. Even in the 70s they were saying some mild detonation on occasion is fine.
I've driven/owned vehicles that had mild detonation and those that had none. My last 390 had some detonation at times - especially in hot weather, but it wasn't destructive (I also changed from the stock type pistons and closed up the quench so it was less severe and less damaging). The current owner is doing fine with it.

I have not heard the ping yours is making so I can't say if it's severe, trouble or not, or something to not worry about. If that's the only time it does it - it's likely not a huge thing. Yes, SOME can be normal. Mine has NO PING. Top on, off, whatever, and when my wife is with me the radio is off (she doesn't care for my music and I can't stand whiney grating country music so it's none when we are both in there)
As far as yours "not downshifting" I don't know what sort of throttle pressure you drive with - if maybe 1/16" more of push would kick it down and get out of the lugging range or not but if it's going to ping due to detonation, that's the exact circumstances I'd expect any engine to do it in.

I stated it wrong, sorry. It is pinging, shit is blowing up in the cylinder at the wrong time. I even ran a few tanks of higher octane and it still does it.. Any ping is not good I thought because it is a force on the piston at the wrong time. Maybe I have thought wrong all these years. I have had many many vehicles and none have sounded like this. I wish I would have bought an extended warranty.

 

[NateO]

Attached is the 09-013-20 REV. A TSB for the Spark Plugs. It was a bitch to get as it was not on the interwebs anywhere. Had to go to Tech Authority and pull it up there. Does not seem to be assigned by VIN to anything I tried to input. They seem to really want this one buried.

What is interesting is they list other 2020-2021 models as being affected but only 2021 for the Gladiator and Wrangler. Then the build on and after and before info is contradictory. I think this has been an issue with bad crack spark plugs on the Gladiator from the get go of the 2020 model year even with the early 2019 build date models.

Seems the MOPAR OEM spark plugs are made by Champion and that would explain a lot with the crappy quality.

This was a great add. My truck is at the shop now and has been all day its now 1:00pm and they still "cant" find anything wrong. I call and shared this info. They are looking into it! Hopefully that fixes my issues.

 

[NateO]

This was a great add. My truck is at the shop now and has been all day its now 1:00pm and they still "cant" find anything wrong. I call and shared this info. They are looking into it! Hopefully that fixes my issues.

UPDATE: 7/26/21
Dodge looked into the TSB report on the spark plug then said they were good. They did find a new TSB report that stated the Right side Cam shaft needs to be replaced. Reports of engine noises, rough idles. They will be replacing mine once it arrives.

 

[Scrubb84]

UPDATE: 7/26/21
Dodge looked into the TSB report on the spark plug then said they were good. They did find a new TSB report that stated the Right side Cam shaft needs to be replaced. Reports of engine noises, rough idles. They will be replacing mine once it arrives.

Do you happen to know this TSB #?

 

[SelfmodJT]

mmmmm, apparently not ;-) because there's no such thing as "pre-detonation".
I've outlined what they are and what the differences are several times in this thread and in others.

PREIGNITION is when something ignites the fuel BEFORE the normal spark ignites it.
That "something" can be a hot ember, carbon, overly high compression, etc. but preignition is when the charge is lit too early and the advancing flame front from THAT fire hits the flame front from the later-lit normally burning charge and the "boom" resonates in the block.

DETONATION is when the normal advancing flame front heats and compresses the unburned fuel enough it self-ignites.
It's where the unburned fuel is literally pushed harder and harder into a "corner" which causes heat because compressing a gas heats it and the fuel can't resist self-igniting.
The flame front from that burn collides with the normally advancing flame from from the normal burn and boom.
It's one or the other, not both.

What happens with detonation is that sometimes under certain conditions or where it's severe enough (loud enough, constant enough) the collision literally blows the protective layer of unburned charge (the boundary layer) away from the top of the piston exposing it to temperatures high enough to melt aluminum (and the extreme pressure all at once can also break off the edges of the top of the piston, besides causing it to melt)
It also often cracks spark plug porcelain which can lead to a misfire.

Some detonation is not going to hurt anything. Even in the 70s they were saying some mild detonation on occasion is fine.
I've driven/owned vehicles that had mild detonation and those that had none. My last 390 had some detonation at times - especially in hot weather, but it wasn't destructive (I also changed from the stock type pistons and closed up the quench so it was less severe and less damaging). The current owner is doing fine with it.

I have not heard the ping yours is making so I can't say if it's severe, trouble or not, or something to not worry about. If that's the only time it does it - it's likely not a huge thing. Yes, SOME can be normal. Mine has NO PING. Top on, off, whatever, and when my wife is with me the radio is off (she doesn't care for my music and I can't stand whiney grating country music so it's none when we are both in there)
As far as yours "not downshifting" I don't know what sort of throttle pressure you drive with - if maybe 1/16" more of push would kick it down and get out of the lugging range or not but if it's going to ping due to detonation, that's the exact circumstances I'd expect any engine to do it in.

Just out of curiosity, why doesnt the knock senor catch the rattle and vibration?

 

[SelfmodJT]

.

 

[ShadowsPapa]

UPDATE: 7/26/21
Dodge looked into the TSB report on the spark plug then said they were good. They did find a new TSB report that stated the Right side Cam shaft needs to be replaced. Reports of engine noises, rough idles. They will be replacing mine once it arrives.

Several people have said their shop replaced the right side cam - and that was before the TSB you mentioned assuming "new" means in the last 4 or 5 months.

Just out of curiosity, why doesnt the knock senor catch the rattle and vibration?

There's a great question! All I can figure is that the tune on these things can't make the change needed for some reason - I'd also love to know what the engine temperatures are at the times this happens, or even chamber temperatures. Someone suggested that the "ping" was actually preignition - weird, there would have to be extreme conditions to cause the fuel to ignite BEFORE the spark and if that were the case, changing timing would do little to nothing.
Mine doesn't ping - I've spent months trying to listen for it because so many comment about ping, but mine is honestly really quiet.

No misfires, no ping, nothing abnormal about the engine. But then the way mine poorly towed my empty trailer I sometimes think the tune in my PCM has to be pretty bad. It's zippy until you put 1500 pounds behind it and then you think you have 4,000 pounds behind it. Maybe that's why mine doesn't ping or rattle or misfire LOL

 

[SelfmodJT]

Several people have said their shop replaced the right side cam - and that was before the TSB you mentioned assuming "new" means in the last 4 or 5 months.



There's a great question! All I can figure is that the tune on these things can't make the change needed for some reason - I'd also love to know what the engine temperatures are at the times this happens, or even chamber temperatures. Someone suggested that the "ping" was actually preignition - weird, there would have to be extreme conditions to cause the fuel to ignite BEFORE the spark and if that were the case, changing timing would do little to nothing.
Mine doesn't ping - I've spent months trying to listen for it because so many comment about ping, but mine is honestly really quiet.

No misfires, no ping, nothing abnormal about the engine. But then the way mine poorly towed my empty trailer I sometimes think the tune in my PCM has to be pretty bad. It's zippy until you put 1500 pounds behind it and then you think you have 4,000 pounds behind it. Maybe that's why mine doesn't ping or rattle or misfire LOL

I have noticed the rattle does not happen until it has been driven for about 15 mins. Its definitely the same sound as when the engine is lugging or about to stall but less pronounced. Mine is very short and at random intervals between 1 to 2.5 rpms mostly on inclines but i did notice a few times it did it on a decline that makes me wonder if the throttle has anything to do with it. I still dont understand why the noise seems like its coming from the middle of the undercarragie and not from the engine, maybe i also have something loose. And how do you not lugg the engine on a steep incline without somewhat burning the clutch? Almost impossible.

 

[SelfmodJT]

And by burning i mean by not going to 2k rpms before engaging the clutch. On flat roads i can engage the clutch at 1k rpms smooth as butter.

 

[ShadowsPapa]

I have noticed the rattle does not happen until it has been driven for about 15 mins. Its definitely the same sound as when the engine is lugging or about to stall but less pronounced. Mine is very short and at random intervals between 1 to 2.5 rpms mostly on inclines but i did notice a few times it did it on a decline that makes me wonder if the throttle has anything to do with it. I still dont understand why the noise seems like its coming from the middle of the undercarragie and not from the engine, maybe i also have something loose. And how do you not lugg the engine on a steep incline without somewhat burning the clutch? Almost impossible.

Downshift...... lugging is when the increase in throttle pressure doesn't result in an increase in RPM because the RPM is too low for the load. Run the RPMs up.
If you are running 3,000 RPM or better unlikely you are lugging unless you press the pedal and nothing happens.
I downshift. Wind 'er up.
I match engine RPM to road speed best I can before letting clutch back out.
Heck, I downshift and come within 250 rpm or so of red-lining my 4.0 (and it's got a different cam to increase torque and throttle response and a shaved head)
The 3.6 will handle RPM far better than a long-throw 4.0.
So far every clutch I've had has gone 100,000 miles (except my first car when I was 14 - I went through a clutch and 3 transmissions)

 

[SelfmodJT]

Downshift...... lugging is when the increase in throttle pressure doesn't result in an increase in RPM because the RPM is too low for the load. Run the RPMs up.
If you are running 3,000 RPM or better unlikely you are lugging unless you press the pedal and nothing happens.
I downshift. Wind 'er up.
I match engine RPM to road speed best I can before letting clutch back out.
Heck, I downshift and come within 250 rpm or so of red-lining my 4.0 (and it's got a different cam to increase torque and throttle response and a shaved head)
The 3.6 will handle RPM far better than a long-throw 4.0.
So far every clutch I've had has gone 100,000 miles (except my first car when I was 14 - I went through a clutch and 3 transmissions)

Lol, ill be getting about 10mpg then. Blah, honestly i dont even care about the noise as long as the engine doesnt blow on me. Clutch wise, idc either because i want to upgrade reguarless.

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