Rattle from engine when accelerating (sounds like keys)

[snazzi_scarlett]

So I've been getting this rattle for atleast the last 10k. Slowly getting more prominent, it's like a key rattle/diesel clatter. Mainly is 1-3 gear but can hear it in 4th rarely. Lower speeds/light throttle. Hot, warm, or cold engine and ambient Temps. I can hear it more when I'm offroading in 2H, 4H, or 4L because it's low speed low throttle input.

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[SelfmodJT]

So I've been getting this rattle for atleast the last 10k. Slowly getting more prominent, it's like a key rattle/diesel clatter. Mainly is 1-3 gear but can hear it in 4th rarely. Lower speeds/light throttle. Hot, warm, or cold engine and ambient Temps. I can hear it more when I'm offroading in 2H, 4H, or 4L because it's low speed low throttle input.

Do you hear it before the oil temp get to 175? If you do it might be just a rattle. You shouldnt really hear it until the oil gets to operating temperature if its pre dentonation from my understanding. Do you hear it when accelerating going down hill on light throttle?

 

[snazzi_scarlett]

Do you hear it before the oil temp get to 175? If you do it might be just a rattle. You shouldnt really hear it until the oil gets to operating temperature if its pre dentonation from my understanding. Do you hear it when accelerating going down hill on light throttle?

It isn't persistent, it's definitely occasionally on road and very often offroad(which makes me think wind noise is preventing me from hearing it on road). When I hear it, doesn't matter where the temp Guage is. I don't hear it downhill but then again I don't accelerate downhill. It's definitely more prominent when I'm at engine temp.

 

[@californiajeeping]

I had this on my 2020 bad> Traded for a diesel. dealer said light acceleration pinging was normal. It was absolutely not normal. As my 2015 wrangler did not have that particular issue or sound.

My engine also had the very rough idle discussed here and the misfire codes.

running 91 with some octane booster improved it 60% but didnt fix the rough idle or misfire at extended high rpm (snow wheeling or in the dunes full throttle for more than 10 seconds it would intermittently throw multiple misfire codes).

 

[ShadowsPapa]

Do you hear it before the oil temp get to 175? If you do it might be just a rattle. You shouldnt really hear it until the oil gets to operating temperature if its pre dentonation from my understanding. Do you hear it when accelerating going down hill on light throttle?

Oil temperature has little to do with it. It's the combustion chamber temperatures, the head of the piston and chamber. Detonation.........
If it's detonation - the charge is lit by the normal spark from ignition system. The charge burn, the flame front advances across the chamber and forces the unburned gas "into a corner" so to speak.
The unburned charge is compressed by the advancing flame front until the heat of compression with the heat in the chamber reach a point the fuel self-ignites.
So it's a secondary lighting of unburned charge caused by the heat - of being compressed and chamber heat. The two flame fronts collide and create a sort of sonic boom that resonates in the block - the "ping" sound.
Swirl chambers, intakes that cause turbulence in the air as it comes it to keep it moving, and a quench chamber can all work to keep the mixture moving so it is less prone to detonation.

(there's pre-ignition where the charge is lit before spark and there's detonation where the charge is lit, then the unburned fuel is compressed to self-ignition)

Oil temperature can be an indication of engine temperature but doesn't have to be. It takes a lot longer for the oil to get near 200 than it does for the coolant and chamber to reach temperatures ripe for detonation.
I've had oil temps of 170 but coolant temps of around 200, and I've seen them cross in temperatures.

 

[Scrubb84]

So I've been getting this rattle for atleast the last 10k. Slowly getting more prominent, it's like a key rattle/diesel clatter. Mainly is 1-3 gear but can hear it in 4th rarely. Lower speeds/light throttle. Hot, warm, or cold engine and ambient Temps. I can hear it more when I'm offroading in 2H, 4H, or 4L because it's low speed low throttle input.

This is exactly what mine does. If conditions are just right (slight incline on a long back road, in 2nd or 3rd gear) It can carry this fn rattle for a 1/4 mile. Let me kno if you ever figure it out 100% what it is. Mine seems to be the worst case of this and no dealer in my area will even attempt to diagnose correctly. Excuses is all they offer me.

 

[@californiajeeping]

This is exactly what mine does. If conditions are just right (slight incline on a long back road, in 2nd or 3rd gear) It can carry this fn rattle for a 1/4 mile. Let me kno if you ever figure it out 100% what it is. Mine seems to be the worst case of this and no dealer in my area will even attempt to diagnose correctly. Excuses is all they offer me.

It is light acceleration pinging/detonation. Why? because the ecu is constantly "leaning" out the mixture for economy to the point that high load low rpm before the vvtl switches over causing a lean spot that detonates. The ecu does nudge the mixture back to the rich side because its only for a short instance.

I garuntee a tune from a reputable tuner will clear this up.

 

[shokker70]

It is light acceleration pinging/detonation. Why? because the ecu is constantly "leaning" out the mixture for economy to the point that high load low rpm before the vvtl switches over causing a lean spot that detonates. The ecu does nudge the mixture back to the rich side because its only for a short instance.

I garuntee a tune from a reputable tuner will clear this up.

I guarantee you it is not that. But I'm 100% sure we're not all talking about the same sound. Mine did it at idle, 30MPH, etc. No rhyme or reason, cold, hot, steady speeds, accelerating. None of it mattered.

 

[Scrubb84]

It is light acceleration pinging/detonation. Why? because the ecu is constantly "leaning" out the mixture for economy to the point that high load low rpm before the vvtl switches over causing a lean spot that detonates. The ecu does nudge the mixture back to the rich side because its only for a short instance.

I garuntee a tune from a reputable tuner will clear this up.

This sounds 100% correct to me, but the only way to fix it is to spend $2k on getting the pcm unlocked/new pcm, correct? Thats some fn ?? right there. I got a star case open about it too, needles to say they dont give a single f either.

 

[ShadowsPapa]

It is light acceleration pinging/detonation. Why? because the ecu is constantly "leaning" out the mixture for economy to the point that high load low rpm before the vvtl switches over causing a lean spot that detonates. The ecu does nudge the mixture back to the rich side because its only for a short instance.

I garuntee a tune from a reputable tuner will clear this up.

Dave.

 

[NachoRuby]

This is exactly what mine does. If conditions are just right (slight incline on a long back road, in 2nd or 3rd gear)

Is yours automatic?

 

[ShadowsPapa]

I guarantee you it is not that. But I'm 100% sure we're not all talking about the same sound. Mine did it at idle, 30MPH, etc. No rhyme or reason, cold, hot, steady speeds, accelerating. None of it mattered.

If it's at idle, it's not the same thing. Cruising won't do it - load does it, generally lower RPM

The VVL lift doesn't change over until 2800 RPM.
If you are under a bit of a load at 2500 or lower RPM in a gear that's fairly high for the road speed and RPM, it's more likely to happen.
If it was detonation you could force it to happen or predict when it was mostly likely, or actually would happen. Steady speeds without a load, say you are on a pretty level road going 45, not pressing the pedal, there would, or should, be no detonation. Cold engines won't- there's not enough heat in the chamber to cause the fuel to ignite.

Most of these are happening waay outside of the range that anything is ready for the lift to change. Normally when you get RPM up that high - into the upper 20s where VVL changes cam profiles, you reduce the detonation.

You know how racers get around detonation with extreme compression? Keep the RPM up high. There's no time for detonation at high RPM because it takes time to happen.
Heat, load, low RPM..........

 

[Scrubb84]

Is yours automatic?

Yes

 

[NachoRuby]

Yes

Interesting. A few of us manual guys are having this issue, so we assumed it was possibly trans related when the dealership told us the same thing. I feel your struggle.

 

[Scrubb84]

Interesting. A few of us manual guys are having this issue, so we assumed it was possibly trans related when the dealership told us the same thing. I feel your struggle.

The few clips ive herd of the guys with manuals having that noise is a completely different noise than what i have. Like someone else said…there are a few ppl on this thread that dont have the same metallic rattle that this thread was started for so it does get a bit confusing.

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