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Rattling upon acceleration

thiskneeguy

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Just wanted to drop a quick note that I recently filled up the tank with BP Ultimate 93 and was driving around yesterday in very hot and humid conditions with engine warmed up and I heard this knocking louder than ever. Normally the higher octane gas kept this noise from happening but definitely not in this case. It's the worst I've ever heard it.
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DougJaneway

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Just wanted to drop a quick note that I recently filled up the tank with BP Ultimate 93 and was driving around yesterday in very hot and humid conditions with engine warmed up and I heard this knocking louder than ever. Normally the higher octane gas kept this noise from happening but definitely not in this case. It's the worst I've ever heard it.
What's weird is I have 34,000 miles now and never hear it anymore. I'm not sure what changed.
 

DougJaneway

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Well that’s good news. Maybe changes in driving habits?
Possible. I also went up to 285/75/17 tires and haven't regeared. It takes higher RPMs in general to reach speed.
 

Mrchams

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I bought my JL Rubicon in April during the Aussie Rona lockdown. That’s what you do during a worldwide pandemic right?!?

I also hear the engine the detonation at low rpm acceleration. It is 100% pinging. If the dealer can’t hear it you’re wasting your time with them.

After looking at this problem closer I noticed it will only detonate when the coolant temp is above 108 deg c (off road page gauge)

My coolant temps will reach as high as 118 deg c when cruising on trails at low speeds. I almost shit myself when seeing such high coolant and oil temps, that’s just too high especially for the oil which will prematurely break down at those temperatures.

High engine temps, too much timing or not enough timing vs coolant temp retard is a recipe for premature piston ring damage and piston bore pitting.

I think Jeep we’re pushing the boundaries when they decided on 11:1 engine comp ratio for pump fuel for the newer pentastar.

My guess is it only happens at low rpm because vct is set for minimal over lap to produce max low down torque.
At higher rpm the vct is set for max power and overlap resulting in lower combustion pressures. Just a guess but the logs will tell the full story.

What will I be doing?

1st I’ll be trying to reduce engine temps by bleeding the cooling system. Hopefully the engine shouldn’t run this hot from factory.

2nd trying to source a cooler thermostat

3rd getting my local HP tuner to increase timing retard at high coolant temps.

4th install an oil cooler.

Fingers crossed.


I originally wrote about this in the engine forum but I'm thinking this may possibly be a transmission problem.

I've noticed recently my Jeep makes a gurgle/rattling noise when accelerating that can be heard from the outside as well as the inside if the windows are down. I was concerned about possible engine knock but use 87 octane per the manual and it has only started recently. It also seems strange that it most noticeably happens when accelerating in 3rd gear (auto transmission but my display tells the current gear).
The noise definitely is louder when going uphill as well.

Another thing that has me concerned it may be the transmission is that the noise does not happen if the gas pedal is pressed while in neutral.

Has anyone else experienced anything like this or know what this noise may be? I'm not super happy cause if its the transmission who knows how long I'll be without it if it needs work... My Jeep is already gonna be in for about 2 weeks of shop time for hail damage as well:mad:.

On the bright side my previous two issues appear to be resolved for now. After finding about 20 fuses that didnt seem fully seated and seating them, my ess has been working and I haven't recieved error codes. The clicking from the suspension when turning has gone away on its own (hopefully for good) as well.

Just needed to vent a bit but if anyone has any ideas what this may be or have any advice I'm open ears. Thanks!
 

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DougJaneway

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I bought my JL Rubicon in April during the Aussie Rona lockdown. That’s what you do during a worldwide pandemic right?!?

I also hear the engine the detonation at low rpm acceleration. It is 100% pinging. If the dealer can’t hear it you’re wasting your time with them.

After looking at this problem closer I noticed it will only detonate when the coolant temp is above 108 deg c (off road page gauge)

My coolant temps will reach as high as 118 deg c when cruising on trails at low speeds. I almost shit myself when seeing such high coolant and oil temps, that’s just too high especially for the oil which will prematurely break down at those temperatures.

High engine temps, too much timing or not enough timing vs coolant temp retard is a recipe for premature piston ring damage and piston bore pitting.

I think Jeep we’re pushing the boundaries when they decided on 11:1 engine comp ratio for pump fuel for the newer pentastar.

My guess is it only happens at low rpm because vct is set for minimal over lap to produce max low down torque.
At higher rpm the vct is set for max power and overlap resulting in lower combustion pressures. Just a guess but the logs will tell the full story.

What will I be doing?

1st I’ll be trying to reduce engine temps by bleeding the cooling system. Hopefully the engine shouldn’t run this hot from factory.

2nd trying to source a cooler thermostat

3rd getting my local HP tuner to increase timing retard at high coolant temps.

4th install an oil cooler.

Fingers crossed.
Let us know how this turns out. I'm very interested in the oil cooler and cooler thermostat ideas.
 

AU_JLU

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I bought my JL Rubicon in April during the Aussie Rona lockdown. That’s what you do during a worldwide pandemic right?!?

I also hear the engine the detonation at low rpm acceleration. It is 100% pinging. If the dealer can’t hear it you’re wasting your time with them.

After looking at this problem closer I noticed it will only detonate when the coolant temp is above 108 deg c (off road page gauge)

My coolant temps will reach as high as 118 deg c when cruising on trails at low speeds. I almost shit myself when seeing such high coolant and oil temps, that’s just too high especially for the oil which will prematurely break down at those temperatures.

High engine temps, too much timing or not enough timing vs coolant temp retard is a recipe for premature piston ring damage and piston bore pitting.

I think Jeep we’re pushing the boundaries when they decided on 11:1 engine comp ratio for pump fuel for the newer pentastar.

My guess is it only happens at low rpm because vct is set for minimal over lap to produce max low down torque.
At higher rpm the vct is set for max power and overlap resulting in lower combustion pressures. Just a guess but the logs will tell the full story.

What will I be doing?

1st I’ll be trying to reduce engine temps by bleeding the cooling system. Hopefully the engine shouldn’t run this hot from factory.

2nd trying to source a cooler thermostat

3rd getting my local HP tuner to increase timing retard at high coolant temps.

4th install an oil cooler.

Fingers crossed.
Mrchams, Finally another australian JL who is having the same issue. The dealers in brisbane are useless. I have found it gets worse on bp98 which is odd because previous performance cars I've owned loved it. Because my dealer failed me and I can't find anyone to tune the cruise map I started to experiment with e85 mixes. I found that if you mix e85 with premium 98 to about 10% ethanol content, the pinging was greatly reduced. Ethanol is more resistant to pinging, reducing cylinder temps and the e85 is a higher octane rating. At 10-15% the stock fuel system and tune can handle it. There is no question the pinging is down to the PCM tune. Please keep us updated with your progress. I would really like to find a way to tune this out. I wonder how long till one of these pinging JLs destroys a piston.
 

Mrchams

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Mrchams, Finally another australian JL who is having the same issue. The dealers in brisbane are useless. I have found it gets worse on bp98 which is odd because previous performance cars I've owned loved it. Because my dealer failed me and I can't find anyone to tune the cruise map I started to experiment with e85 mixes. I found that if you mix e85 with premium 98 to about 10% ethanol content, the pinging was greatly reduced. Ethanol is more resistant to pinging, reducing cylinder temps and the e85 is a higher octane rating. At 10-15% the stock fuel system and tune can handle it. There is no question the pinging is down to the PCM tune. Please keep us updated with your progress. I would really like to find a way to tune this out. I wonder how long till one of these pinging JLs destroys a piston.
I totally agree with you. I too had great success with BP98 with previous performance cars but in my case I too found the detonation was louder. I ran a tank of Nulon Pro strength octane booster which reduced it greatly.
E85 is an amazing fuel. I was running this in my GTR full time, it was very thirsty but the power was like a drug.

Anyway, your fuel mixing is a great short term solution. Thanks for sharing.
Yes I will keep you updated with what I find.
I’ll work on it next week
 

AU_JLU

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I totally agree with you. I too had great success with BP98 with previous performance cars but in my case I too found the detonation was louder. I ran a tank of Nulon Pro strength octane booster which reduced it greatly.
E85 is an amazing fuel. I was running this in my GTR full time, it was very thirsty but the power was like a drug.

Anyway, your fuel mixing is a great short term solution. Thanks for sharing.
Yes I will keep you updated with what I find.
I’ll work on it next week
I’ve been trying to research how well the JL 3.6 will handle e85. You might have some info or thoughts on it from your experience with the GTR. I know the 3.6 comes in a flex fuel variant. From what I can work out the differences between that and the version in the wrangler is the flex fuel sensor, pcm tune and a slim chance it has different injectors or fuel pump. So in theory there shouldn’t be any detrimental effects running e85 mixes in the 15% ethanol range. What do you think?
 

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traxtion

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I’ve been trying to research how well the JL 3.6 will handle e85. You might have some info or thoughts on it from your experience with the GTR. I know the 3.6 comes in a flex fuel variant. From what I can work out the differences between that and the version in the wrangler is the flex fuel sensor, pcm tune and a slim chance it has different injectors or fuel pump. So in theory there shouldn’t be any detrimental effects running e85 mixes in the 15% ethanol range. What do you think?
In the U.S. there is a dealer bulletin recommending avoiding E85 for the 3.6. I don't believe the tune is optimal but every engine is different... if it works for you, run it
 
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traxtion

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I bought my JL Rubicon in April during the Aussie Rona lockdown. That’s what you do during a worldwide pandemic right?!?

I also hear the engine the detonation at low rpm acceleration. It is 100% pinging. If the dealer can’t hear it you’re wasting your time with them.

After looking at this problem closer I noticed it will only detonate when the coolant temp is above 108 deg c (off road page gauge)

My coolant temps will reach as high as 118 deg c when cruising on trails at low speeds. I almost shit myself when seeing such high coolant and oil temps, that’s just too high especially for the oil which will prematurely break down at those temperatures.

High engine temps, too much timing or not enough timing vs coolant temp retard is a recipe for premature piston ring damage and piston bore pitting.

I think Jeep we’re pushing the boundaries when they decided on 11:1 engine comp ratio for pump fuel for the newer pentastar.

My guess is it only happens at low rpm because vct is set for minimal over lap to produce max low down torque.
At higher rpm the vct is set for max power and overlap resulting in lower combustion pressures. Just a guess but the logs will tell the full story.

What will I be doing?

1st I’ll be trying to reduce engine temps by bleeding the cooling system. Hopefully the engine shouldn’t run this hot from factory.

2nd trying to source a cooler thermostat

3rd getting my local HP tuner to increase timing retard at high coolant temps.

4th install an oil cooler.

Fingers crossed.
After reading this last night, I took my wrangler out and got engine to OT to recreate the noise and watch coolant temperature. The noise started in a normal OT range, but after driving around in neighborhoods, I got the coolant just shy of 221F/105C and began hearing the worst and most consistent noise I have heard yet. It was even lightly spark knocking when accelerating in 1st Gear, especially on hills.

My observations match yours - the engine ping actually worsens as coolant temperature increases well after operating temperature is reached. It was a fairly cool night for the Washington D.C. area (84F/29C). All of these temperatures are considered normal range and wouldn't be flagged as irregular in the logs.

This was most disturbing because it is clear that my driving habits could not have been a leading factor. Spark knocking in first gear is not something that should ever be happening...
 

DougJaneway

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Doesn't the Gladiator have an over sized radiator and wider grille openings? What about a radiator and grille swap?
 

AU_JLU

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Doesn't the Gladiator have an over sized radiator and wider grille openings? What about a radiator and grille swap?
On the gladiator forum people are also reporting spark knock under the same conditions. :(
 
 



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