Rattle from engine when accelerating (sounds like keys)

[Scrubb84]

And the dealer said or used the word "pre-detonation" ?
There's no such term.............. I guess dealers don't know the difference between pre-ignition and detonation. They can't fix what they can't even describe.
No wonder people are having issues.
First they have to understand what each is, then what causes each one, before they can do anything.
A certain amount of ping from detonation is not unexpected but it should be barely audible, not "loud".

I can't even FORCE mine to ping or detonate. I've tried both of our Jeeps (both have 3.6) and nope, not a sound. Even going up a fair hill, accelerating with it in the lower RPM range, or holding the brake and giving it gas while in gear as if to do "a brake stand" - no ping.

Most dealers don’t know anything besides what they can find on google, and that’s suggesting they even know how to use google. Sad world we live in.
You bring up a good point here tho... not every jt has this issue. So I’m looking for a bad part or something, just like the steering box issue. Some are good, some are complete garbage.

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[IanNubbit]

well noise has gotten worse and this summer had a different dealer check it and they said it was normal and pre-detonation is the reason. Yeah, really don't think so.

So I had a truck come in once with the same concern. There was a TSB about the FAD having a rattle on acceleration. Inspected, nothing found, but I went ahead and noticed that the axle was like 1/4 quart low on fluid. So I added Lucas in there as a replacement. Customer hasent been back for 5 months now since. Might be worth a shot? I know it sounds crazy, but even in the TSB they describe that customers state it’s a Engine noise. Also something for you to try, try and see if the noise goes away or still occurs if you shift to 4 high

 

[Scrubb84]

I bought a cheap scan tool and showed my dealer the results of my long term fuel trim of -4.5 & -7.9 and the tech said directly to me “yea, that’s not right. But there’s nothing we can do until there is a tsb or something”. This is what I’m dealing with. The human race is doomed.

 

[ShadowsPapa]

So I had a truck come in once with the same concern. There was a TSB about the FAD having a rattle on acceleration. Inspected, nothing found, but I went ahead and noticed that the axle was like 1/4 quart low on fluid. So I added Lucas in there as a replacement. Customer hasent been back for 5 months now since. Might be worth a shot? I know it sounds crazy, but even in the TSB they describe that customers state it’s a Engine noise. Also something for you to try, try and see if the noise goes away or still occurs if you shift to 4 high

I know there's at least 2, maybe 3, versions of that FAD TSB. Apparently there's a lot of slop or play in there and sometimes it gets excessive enough to make bad sounds.

I bought a cheap scan tool and showed my dealer the results of my long term fuel trim of -4.5 & -7.9 and the tech said directly to me “yea, that’s not right.

How's that so much different from my wife's Grand Cherokee -3.13 -7.04
You are at -4.5 and -7.9
Your numbers are higher but almost proportionately higher

Her GC 4.6 numbers AT THAT TIME -
Short Term Fuel Trim - Bank 1: 12.49 %
Long Term Fuel Trim - Bank 1: -3.13 %
Short Term Fuel Trim - Bank 2: 9.37 %
Long Term Fuel Trim - Bank 2: -7.04 %

OK, where's Dave when you need him......

 

[zprovo]

My 2020 Gladiator pings. I can hear it with the doors off really well, and pretty well with the windows down. I can bearly hear it windows up. It usually happens right when I get back on the gas from coasting down like over a speed hump (low speed, low revs, automatic transmission).
I drove my father's 2018 JL and I was able to make it ping under similar conditions (though his is a manual transmission) getting back on the gas after coasting down leaving it in second when it might have been happier in first.
The common denominators are me and the motor. I'm guessing it's probably fine, but my OCD is tickled a bit every time I hear it.

 

[Scrubb84]

I know there's at least 2, maybe 3, versions of that FAD TSB. Apparently there's a lot of slop or play in there and sometimes it gets excessive enough to make bad sounds.



How's that so much different from my wife's Grand Cherokee -3.13 -7.04
You are at -4.5 and -7.9
Your numbers are higher but almost proportionately higher

Her GC 4.6 numbers AT THAT TIME -
Short Term Fuel Trim - Bank 1: 12.49 %
Long Term Fuel Trim - Bank 1: -3.13 %
Short Term Fuel Trim - Bank 2: 9.37 %
Long Term Fuel Trim - Bank 2: -7.04 %

OK, where's Dave when you need him......

There’s probably an issue with the GC then too.
Am I wrong in thinking a brand new vehicle should be perfectly balanced from factory. Ever heard of the stoichiometric ratio? Pretty sure theres a problem and my pinging/rattling (whatever u wanna call it) is super loud when its warm out.

 

[LostWoods]

How's that so much different from my wife's Grand Cherokee -3.13 -7.04
You are at -4.5 and -7.9
Your numbers are higher but almost proportionately higher

Her GC 4.6 numbers AT THAT TIME -
Short Term Fuel Trim - Bank 1: 12.49 %
Long Term Fuel Trim - Bank 1: -3.13 %
Short Term Fuel Trim - Bank 2: 9.37 %
Long Term Fuel Trim - Bank 2: -7.04 %

OK, where's Dave when you need him......

Used to do drivability for a living and those numbers are excellent. That's not absolute percentage it's a percentage representative of the range the fuel map is programmed for. You worry when you both are large in the same direction and none of these are even close.

They are also not additive so a STFT of -50% might be corrected by a LTFT adjustment of +0.2%. STFT is super sensitive to certain issues.

 

[ShadowsPapa]

There’s probably an issue with the GC then too.
Am I wrong in thinking a brand new vehicle should be perfectly balanced from factory. Ever heard of the stoichiometric ratio? Pretty sure theres a problem and my pinging/rattling (whatever u wanna call it) is super loud when its warm out.

I know all about A/F ratios, shoich running and so on. Been at carburetor school put on by Sun etc. 14.7 to 1 ideally.
This is only stating that the ecu is adjusting downward based on the short term numbers which come from the O2 sensor voltages.
And my numbers are at idle. (and an occasional misfire so it's likely running a tad rich at the time these numbers were gathered?)

There's no such thing as "perfectly balanced from the factory" because air pressure, air temperature, throttle position, load, speed, engine temperature and more impact how completely something burns. Even if it left the factory with a perfect balance - that would be at a given speed and load and any variables at all, any, (atmospheric pressure, ambient temperatures, engine temperatures and more) will change it.

I'm no expert on exactly -PRECISELY how these all work but there's no problem here - those numbers at idle and based on downstream sensors - long term, it only means the ecu is shortening the injector open time if I have my ducks in a rows.
Long term is well under 10% which is what I was told is the upper limit to watch (indicating possible issues like injector issues, bad O2 sensors, etc.)
The Grand Cherokee was at idle and had less than 1,000 miles on it.
So there's nothing at all to be alarmed about with the numbers on the Grand Cherokee. It's running great, no misfires, no ping and mpg is easily 24-25 in moderate weather.

Question for the pro -

They are also not additive so a STFT of -50% might be corrected by a LTFT adjustment of +0.2%. STFT is super sensitive to certain issues.

Isn't the LTFT based on the numbers from the STFT - which happen much more quickly based on the O2 sensor voltages not oscillating between 0 and 1 or was it less than 1..... but sticking with higher voltages or lower voltages below .45 volts?
Been a long time since I've done that much math HAHA

 

[Deleted member 30519]

Mine starts to do it more when it gets cold but it's a hit or miss. 2020 6spd with 13k miles so far.

 

[ShadowsPapa]

Mine starts to do it more when it gets cold but it's a hit or miss. 2020 6spd with 13k miles so far.

Ping of detonation (or even pre-ignition) is generally worse when ambient temperatures and engine temperatures are HOT. Detonation is due to unburned fuel self-igniting after the spark has already taken place, pre-ignition is caused by something hot igniting the fuel before the normal spark.
Odd that it would be that if it's worse when colder.

 

[Deleted member 30519]

Ping of detonation (or even pre-ignition) is generally worse when ambient temperatures and engine temperatures are HOT. Detonation is due to unburned fuel self-igniting after the spark has already taken place, pre-ignition is caused by something hot igniting the fuel before the normal spark.
Odd that it would be that if it's worse when colder.

Is this something I should inform the dealer about again? The last time they blamed it on my track bar not being torqued to spec and robbed me a few hundred to tighten all the suspension.

 

[ShadowsPapa]

Is this something I should inform the dealer about again? The last time they blamed it on my track bar not being torqued to spec and robbed me a few hundred to tighten all the suspension.

Your dealer shop guys need to go back to school.
And when diagnosing an issue, and in doing so the torque things to spec - they charged for that? If things were out of spec, why would you pay for that (unless you replaced the track bar.)

 

[Deleted member 30519]

Your dealer shop guys need to go back to school.
And when diagnosing an issue, and in doing so the torque things to spec - they charged for that? If things were out of spec, why would you pay for that (unless you replaced the track bar.)

Yeah I have the RC 3.5" kit with the adjustable track bar. They blamed it on loose track bar and said the shock mounts were over torqued.

 

[ShadowsPapa]

Yeah I have the RC 3.5" kit with the adjustable track bar. They blamed it on loose track bar and said the shock mounts were over torqued.

Fair enough - but still can't imagine a "rattle" that sounds like a ping, keys or an exhaust shield coming from a trackbar.......... something like that would rattle due to road roughness, not the engine rpm or acceleration.

 

[Scrubb84]

Is my understanding of the timing advance wrong too???
At idle in park without touching anything it ranges from 1.5 to 10.5
I think that’s bad.

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