Rattle from engine when accelerating (sounds like keys)

[ShadowsPapa]

What makes you think those numbers are bad?

Timing is controlled by the ecu on an "as needed" basis - unlike the old school systems where it was purely RPM-based with vacuum advance determining timing based on load.

10 degrees isn't out of the realm of reality at idle. Likely you'd never see it advanced more than that at idle because the engine running slowly the burn has time to progress in the cylinder and give peak pressures at ~ 14 to 16 ATDC.

The PCM determines timing based on several factors including intake air pressure, intake air temperature, engine temperature, EGR can come into play.

I noticed my wife's GC was at -2.00 degrees at idle multiple times. That's a bit retarded but again, not out of what I've seen over the years in older engines so it likely had a reason.

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[Scrubb84]

What makes you think those numbers are bad?

Timing is controlled by the ecu on an "as needed" basis - unlike the old school systems where it was purely RPM-based with vacuum advance determining timing based on load.

10 degrees isn't out of the realm of reality at idle. Likely you'd never see it advanced more than that at idle because the engine running slowly the burn has time to progress in the cylinder and give peak pressures at ~ 14 to 16 ATDC.

The PCM determines timing based on several factors including intake air pressure, intake air temperature, engine temperature, EGR can come into play.

I noticed my wife's GC was at -2.00 degrees at idle multiple times. That's a bit retarded but again, not out of what I've seen over the years in older engines so it likely had a reason.

It’s the bouncing around that doesn’t seem right to me.

 

[LostWoods]

It’s the bouncing around that doesn’t seem right to me.

ECU programming is designed around slight overcompensation and it is never dead on because it's trying to hit like 7 targets at once. Emissions controls have a highly complex relationship so I wouldn't worry about it.

 

[ShadowsPapa]

ECU programming is designed around slight overcompensation and it is never dead on because it's trying to hit like 7 targets at once. Emissions controls have a highly complex relationship so I wouldn't worry about it.

That, and timing is one of the things used with EGR and fuel mix to control emissions.
Timing of slightly retarded to about 10 at idle isn't out of reality. And to see it move means it was at least getting input from something.
This is where I'd dearly love to spend a day with Dave over in IL and update my automotive education, modernize what I know.

 

[tumbes2000]

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.

Same conditions for me. Doesn't last but a second and only happens when at low revs like 1500 or less but high gear like 6 or 7. If I make it shift by adding more throttle it doesnt happen. On small hills or stop and go on a larger hill is when it generally happens. Wouldn't be happening if transmission wouldn't hold high gears when the rpms drop so much. Colder weather makes it less frequent from what I can tell.

 

[ShadowsPapa]

Same conditions for me. Doesn't last but a second and only happens when at low revs like 1500 or less but high gear like 6 or 7. If I make it shift by adding more throttle it doesnt happen. On small hills or stop and go on a larger hill is when it generally happens. Wouldn't be happening if transmission wouldn't hold high gears when the rpms drop so much. Colder weather makes it less frequent from what I can tell.

That's my main beef with the transmission - it holds high gears to the point of lugging the engine and letting the RPM get way too low.

 

[Higher_Ground]

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.

Same with me and my 2020 automatic. I turn up the radio fairly loud which drowns it out and eases my mind. But when the top comes back off next summer it'll bug me again.

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).

This is the exact scenario I have described before, and the most reproducible if I want to make it rattle.

It also happens occasionally when I'm stuck behind someone driving well under the speed limit. If I could give it more throttle I would, but then I'd be on top of the vehicle in front of me.

Same conditions for me. Doesn't last but a second and only happens when at low revs like 1500 or less but high gear like 6 or 7.

Again, same for me (lasts maybe 1 second) at RPMs ~1500. Nearly always in 3rd gear but sometimes in higher gears too (it seems to last longer if it happens in 3rd).

If I make it shift by adding more throttle it doesnt happen. On small hills or stop and go on a larger hill is when it generally happens. Wouldn't be happening if transmission wouldn't hold high gears when the rpms drop so much. Colder weather makes it less frequent from what I can tell.

It does seem to stem from the transmission moving out of 2nd gear too soon on mine.

 

[ShadowsPapa]

This is the exact scenario I have described before, and the most reproducible if I want to make it rattle.

It also happens occasionally when I'm stuck behind someone driving well under the speed limit. If I could give it more throttle I would, but then I'd be on top of the vehicle in front of me.

And that's something along the lines of my earlier post. Sometimes it simply stays in a gear too long even when the RPM is way under where it should be. I'm going to guess (and likely would win if it were a bet haha) that they do this for MPG. But it's engine abuse, IMO.
There's a way around it - pop the lever to the left, push it forward, force a gear drop.
I swear if they reprogram these things just a little bit you'd see less of this sort of thing.
Mine doesn't ping, I can't force it to ping, it's a pretty quiet engine even lugging but that doesn't mean I like to see 1200-1400 rpm going up a 4% grade - it's just wrong.

 

[Scrubb84]

And that's something along the lines of my earlier post. Sometimes it simply stays in a gear too long even when the RPM is way under where it should be. I'm going to guess (and likely would win if it were a bet haha) that they do this for MPG. But it's engine abuse, IMO.
There's a way around it - pop the lever to the left, push it forward, force a gear drop.
I swear if they reprogram these things just a little bit you'd see less of this sort of thing.
Mine doesn't ping, I can't force it to ping, it's a pretty quiet engine even lugging but that doesn't mean I like to see 1200-1400 rpm going up a 4% grade - it's just wrong.

If someone can figure out how to reprogram this horrible shifting, I would love to know about it.

 

[tumbes2000]

That's my main beef with the transmission - it holds high gears to the point of lugging the engine and letting the RPM get way too low.

I wonder if things would improve if I regeared to 4.88. I have been thinking about it since I might go to 37s and a 2 inch lifts once I am ready for new tires.

 

[Jeepin' John]

Has anybody confirmed for sure that it is engine knock? I've tried by running knock sensors and knock retard on Jscan and i've heard the rattle but Jscan showed 0 degrees knock retard. Not sure if that method is accurate or not to determine if it's real knock or not. Whenever it's really ratting notably, i happen to not be running Jscan. But i have heard it rattle some on Jscan and it didn't show up on knock retard

 

[ShadowsPapa]

Has anybody confirmed for sure that it is engine knock? I've tried by running knock sensors and knock retard on Jscan and i've heard the rattle but Jscan showed 0 degrees knock retard. Not sure if that method is accurate or not to determine if it's real knock or not. Whenever it's really ratting notably, i happen to not be running Jscan. But i have heard it rattle some on Jscan and it didn't show up on knock retard

I would bet that not all instances are true "knock" of detonation but are another similar sound from another source. But not being there myself it's impossible to truly diagnose.

 

[NachoRuby]

Mine is in the dealership right now for this, while they are doing my second round of jeep wave oil change/rotation service. They can't seem to find a reason for it, or duplicate it. I actually think it might be the way the hood is bumping against part of my intake. At least, I hope it is.

 

[ShadowsPapa]

Mine is in the dealership right now for this, while they are doing my second round of jeep wave oil change/rotation service. They can't seem to find a reason for it, or duplicate it. I actually think it might be the way the hood is bumping against part of my intake. At least, I hope it is.

For AUTOMATICS, in many, if not most cases, a true engine ping can be forced by holding the brake and pushing on the throttle of a totally warmed up engine. These of course with the modern PCM controls may be different, but I've been able to force engines to ping by putting them under load by doing the old-fashioned brake-stand. Won't work with a high-stall converter and it's a lot harder with a stick of course - you risk heating up the clutch.

 

[NachoRuby]

For AUTOMATICS, in many, if not most cases, a true engine ping can be forced by holding the brake and pushing on the throttle of a totally warmed up engine. These of course with the modern PCM controls may be different, but I've been able to force engines to ping by putting them under load by doing the old-fashioned brake-stand. Won't work with a high-stall converter and it's a lot harder with a stick of course - you risk heating up the clutch.

I'm manual. I think they are just going to floor it up the mountain in 2nd gear to get it under load. The dealership happens to be on the side of a steep climb.

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