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Discussion Starter #1
Yeah... Noticed it on a few hot summer days. I run 87 octane, always (Petro Canada or Shell). Chatted a few times with the service manager at the dealership about it, we couldn't come up with a positive ID on the problem. Then one day I decided to up the octane : bingo, no more funky sounds (they were very intermittent, under very specific load conditions). Went back to the dealership and had another talk with service manager. Senior tech was listening and walked over. He asked me to bring it in, said he had seen this on a Wrangler not too long ago.

So I took it in today. They cleaned the camshaft phasers, apparently the exhaust side were off spec, then they deleted the memory and did a re-learn on the cam-crank (whatever that means). Because there were no fault codes associated with this, they couldn't do it under warranty ; good thing because it only costed me $40, instead of the powertrain deductible (very quick job with their wiTECH tool). So now I wait and see. Kinda warm week up there, but I still have some 89 octane in the tank.

Hopefully I caught this early enough... I'm at 53K miles. Maybe this can help others in the future.

Found this to illustrate how easy it is :
 

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Yeah... Noticed it on a few hot summer days. I run 87 octane, always (Petro Canada or Shell). Chatted a few times with the service manager at the dealership about it, we couldn't come up with a positive ID on the problem. Then one day I decided to up the octane : bingo, no more funky sounds (they were very intermittent, under very specific load conditions). Went back to the dealership and had another talk with service manager. Senior tech was listening and walked over. He asked me to bring it in, said he had seen this on a Wrangler not too long ago.

So I took it in today. They cleaned the camshaft phasers, apparently the exhaust side were off spec, then they deleted the memory and did a re-learn on the cam-crank (whatever that means). Because there were no fault codes associated with this, they couldn't do it under warranty ; good thing because it only costed me $40, instead of the powertrain deductible (very quick job with their wiTECH tool). So now I wait and see. Kinda warm week up there, but I still have some 89 octane in the tank.

Hopefully I caught this early enough... I'm at 53K miles. Maybe this can help others in the future.

Found this to illustrate how easy it is : https://www.youtube.com/watch?v=tp18U3O4lt4
While i'm not going to say it didn't happen I suggest you find an OBD2 tool/program that is able to log knock. If your engine is knocking n 87 octane it has a problem.

You have a 2015 so its the same tune as all the other cherokees, with the exception of the 2014's which have an ever so slightly more aggressive tune, and other than my 2016 i've never heard bit of knock at all.

Again data logging to see when/where in the rpm range is knocking would be very beneficial.

It could be a problem surfacing as I ran an 87 octane tune which did increase timing (and other variables) without any knock.
 

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Discussion Starter #3
While i'm not going to say it didn't happen I suggest you find an OBD2 tool/program that is able to log knock. If your engine is knocking n 87 octane it has a problem.

You have a 2015 so its the same tune as all the other cherokees, with the exception of the 2014's which have an ever so slightly more aggressive tune, and other than my 2016 i've never heard bit of knock at all.

Again data logging to see when/where in the rpm range is knocking would be very beneficial.

It could be a problem surfacing as I ran an 87 octane tune which did increase timing (and other variables) without any knock.
Another parameter I have to deal with : 5 years comes up end of May 2020 (it'll be close on mileage too, for powertrain warranty). It may not get warm enough for me to hear it again, before I get there.

I will look around at scan tools though. Saw a guy on YT doing it with dyno equipment, good to know there may be less expensive solutions...
 

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Here are some ideas:
There should be knock (ping) sensors on the engine someplace to provide information to the computers so they can make the proper adjustments to stop the ping.
The sensors should detect inaudible (to us) ping. On a V6 engine I would think each bank of cylinders has at least one sensor.
I would think that if a sensor is bad it would provide a Code.

Maybe the 87 octane gas is really 85 octane or worse?
Here in MD the government aggressively checks the octane, quality and cleanliness of the fuel. Each state does their own thing, some better, some not so good.
I am sure you know what goes on in Canada.
Maybe Canada always blends a more volatile fuel which is needed in cold climates and it doesn't work well in warmer weather.
Md uses a different blend in Summer and Winter.
When you say warmer weather you probably mean 50 degrees F.

I can see if the VVT doesn't work correctly it could cause pinging.

Back in the good ole days of carburetors, pistons and heads would collect carbon buildup which would increase the compression ratio which would cause ping.
On today's engines I would expect the computers to adjust the timing to prevent ping.

I think a good synthetic motor oil of the correct viscosity is very important for the proper operation and cleanliness of VVT.
In cold climates you get more condensation in the engine.

Does your coolant thermostat work correctly? If they stick open the engine doesn't warm up correctly and causes all kinds of problems.

Check the emissions components, like the EGR valve and positive crankcase ventilation.
I used to disable these systems, don't tell anyone, and my vehicles needed 93 octane or aviation fuel or octane booster or they pinged like crazy.

I enjoyed your video, learn something new every day.
These are just my silly comments so don't beat up on me too bad.
 

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Discussion Starter #5
Here are some ideas:
There should be knock (ping) sensors on the engine someplace to provide information to the computers so they can make the proper adjustments to stop the ping.
The sensors should detect inaudible (to us) ping. On a V6 engine I would think each bank of cylinders has at least one sensor.
I would think that if a sensor is bad it would provide a Code.

Maybe the 87 octane gas is really 85 octane or worse?
Here in MD the government aggressively checks the octane, quality and cleanliness of the fuel. Each state does their own thing, some better, some not so good.
I am sure you know what goes on in Canada.
Maybe Canada always blends a more volatile fuel which is needed in cold climates and it doesn't work well in warmer weather.
Md uses a different blend in Summer and Winter.
When you say warmer weather you probably mean 50 degrees F.

I can see if the VVT doesn't work correctly it could cause pinging.

Back in the good ole days of carburetors, pistons and heads would collect carbon buildup which would increase the compression ratio which would cause ping.
On today's engines I would expect the computers to adjust the timing to prevent ping.

I think a good synthetic motor oil of the correct viscosity is very important for the proper operation and cleanliness of VVT.
In cold climates you get more condensation in the engine.

Does your coolant thermostat work correctly? If they stick open the engine doesn't warm up correctly and causes all kinds of problems.

Check the emissions components, like the EGR valve and positive crankcase ventilation.
I used to disable these systems, don't tell anyone, and my vehicles needed 93 octane or aviation fuel or octane booster or they pinged like crazy.

I enjoyed your video, learn something new every day.
These are just my silly comments so don't beat up on me too bad.
Yep the Pentastars have knock sensors ; they should throw a code when they misbehave.
We have summer/winter gas blends up here too. I only buy from the top players we have, octane level *should* be Ok. Dealer would've had more complaints, I think, if we had a problem with gas locally.
I only use Pennzoil Platinum (it's always on sale somewhere).
Never seen a problem with coolant temps.
For the emissions stuff : again, there should be codes thrown if there is a problem...

I'll trust the senior tech on this, they get regular training for these engines. And I'll keep my ears open...
 

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I think you might have got some bad gas to be honest, its pretty hard to get these vehicle to actually knock. They quite frequently have "burst knock" which you can't hear because its not real and only shows up when logging. Knock sensors can be adjusted to benefit performance without harming the engine. The burst knock is a pain in the ass because the vehicle "fake knocks" and pulls timing during events that the vehicle "thinks" it might be knocking (horrible oversimplification there)

Here's how you change the knock sensor values.....

 

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Discussion Starter #8
Yikes, most of that is way above my pay grade, heh.
I think I can rule out bad gas, because I heard the noise a few times over a couple months, on very warm days. I always buy gas at one of the two busiest gas stations in town (Petro Can or Shell). I almost wish it were bad gas...

I know the Pentastar has had issues with cam rollers, so that was my first guess, but then it would do it constantly..

I knew these engines are very well protected against knocking, which is why I probably shut that assumption out of my mind for so long.

Anyway... I just hope that 1) it's over, and 2) no real damage done, if knocking did occur.
 

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I think you might have got some bad gas to be honest, its pretty hard to get these vehicle to actually knock. They quite frequently have "burst knock" which you can't hear because its not real and only shows up when logging. Knock sensors can be adjusted to benefit performance without harming the engine. The burst knock is a pain in the ass because the vehicle "fake knocks" and pulls timing during events that the vehicle "thinks" it might be knocking (horrible oversimplification there)

Here's how you change the knock sensor values.....

Instead of visiting dealer and talking about things they dont even understand, its better to invest 400$ in HPTuners interface to run VCM Scanner/Editor and play with it yourself. Thats what Tyler did, and I followed him. I don't regret, this was the best investment I made so far in terms of Jeep. I can even say its a must for anyone playing with Cherokee. You can tweak, test and investigate almost all of the issues it can expose (and there are many). Knocks are very easy to track, most of the time you just run VCM Scanner during ride and tweak your spark advance tables to get rid of it. There is a base alcohol part throttle/wot table which might need tweaking if you run better octane fuel.
 

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Yeah... Noticed it on a few hot summer days. I run 87 octane, always (Petro Canada or Shell). Chatted a few times with the service manager at the dealership about it, we couldn't come up with a positive ID on the problem. Then one day I decided to up the octane : bingo, no more funky sounds (they were very intermittent, under very specific load conditions). Went back to the dealership and had another talk with service manager. Senior tech was listening and walked over. He asked me to bring it in, said he had seen this on a Wrangler not too long ago.

So I took it in today. They cleaned the camshaft phasers, apparently the exhaust side were off spec, then they deleted the memory and did a re-learn on the cam-crank (whatever that means). Because there were no fault codes associated with this, they couldn't do it under warranty ; good thing because it only costed me $40, instead of the powertrain deductible (very quick job with their wiTECH tool). So now I wait and see. Kinda warm week up there, but I still have some 89 octane in the tank.

Hopefully I caught this early enough... I'm at 53K miles. Maybe this can help others in the future.

Found this to illustrate how easy it is : https://www.youtube.com/watch?v=tp18U3O4lt4

This is from the owner's manual : 3.2L Engine
These engines are designed to meet all
emissions regulations and provide satisfac
tory fuel economy and performance when
using high quality unleaded gasoline hav
ing an octane range of 87 to 89. The manu
facturer recommends the use of 89 octane premium
gasoline for optimum performance.

I have always use 89 octane gasoline and never had a ping. Yes it is more expensive, but worth it to my opinion. :grin:
 

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Discussion Starter #12
This is from the owner's manual : 3.2L Engine
These engines are designed to meet all
emissions regulations and provide satisfac
tory fuel economy and performance when
using high quality unleaded gasoline hav
ing an octane range of 87 to 89. The manu
facturer recommends the use of 89 octane premium
gasoline for optimum performance.

I have always use 89 octane gasoline and never had a ping. Yes it is more expensive, but worth it to my opinion. :grin:
Yep, I read that too, a long time ago. Not one sound for 80+K kilometers on 87, it wouldn't just start out of nowhere. Now my opinion : oil companies are not getting that extra money from me, if the book says I don't have to. :wink:
 

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This is from the owner's manual : 3.2L Engine
These engines are designed to meet all
emissions regulations and provide satisfac
tory fuel economy and performance when
using high quality unleaded gasoline hav
ing an octane range of 87 to 89. The manu
facturer recommends the use of 89 octane premium
gasoline for optimum performance.

I have always use 89 octane gasoline and never had a ping. Yes it is more expensive, but worth it to my opinion. /images/JeepCherokeeClub_Toucan/smilies/tango_face_grin.png
Yep, I read that too, a long time ago. Not one sound for 80+K kilometers on 87, it wouldn't just start out of nowhere. Now my opinion : oil companies are not getting that extra money from me, if the book says I don't have to. /images/JeepCherokeeClub_Toucan/smilies/tango_face_wink.png
Same here, I am even level above that, my Jeep runs on lpg gas, without knocks. Lpg cost is 40% regular gas here so no brainer.
 

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Maybe depending on location and use. By me 89 is at a minimum +.20 gallon so that is a big consideration.
I started off with 89 on my Cherokee then quickly switched to 87. Have had no issues with pinging to date, 5 years later.
I tow on the highway during the warmer months, and I imagine that introduces some performance issues.
Also basically octane is based on compression ratio needed by the engine, in simple terms. Using higher octane than is needed is of no benefit to the vehicle/engine.

The key to that statement is "recommended" for optimum performance. The question is what is optimum performance? What is optimum performance to a everyday driver. Obviously pinging may very well be a performance issue requiring a boost to 89 at least temporarily.

My considerations on this subject is as follows:
(1). I always use a tier 1 fuel. Simply because tier 1 will have a minimum additive package in the fuel that is above the government mandated minimum.
(2) Buy fuel at a higher volume dealer that is a tier 1. Understanding that gas is generally considered "old" 30 days from the refinery. A slower volume dealer may have fuel received later in the 30 day cycle and have it sitting in their underground tanks for who knows how long.
Then the fuel sits in your vehicle tank for how long.
Fuel will degrade, especially ethanol blended, primarily in the additives/ compounds needed to ignite the fuel properly. The Octane level will decrease over time as these additives/ compounds degrade. That is a key element when dealing with octane numbers.
If you have older fuel in your tank then likely your octane may not even be at the minimum required. Given enough time that could cause issues for your engine.

Buying fuel at a high volume cut rate fuel is probably better than buying tier 1 at a low volume dealer with old fuel in those underground tanks. Fresh fuel at the proper octane is always better for your vehicle. Fortunately most tier 1 dealers do a good volume to keep their tanks "fresh". Tier 1 and "fresh fuel is the best of both worlds.
My humble opinion.:smile:
 

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Optimum performance would mean no detonation and no timing being pulled.

2014 V6 and ONLY 2014 V6 Cherokees have a slightly more aggressive timing curve vs 2015+ models. Its 1.5 degrees more timing. Not much of a difference and even though the manual says 89 i've done extensive logging on my 2014 and 87 works 100% fine with no detonation or timing being pulled, it can achieve its max performance with 87 octane.
 

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Discussion Starter #16
There likely *was* a problem with mine. These engines, whether it's a 2014 3.2L or any other year, a 3.6L Pentastar... they should not ping with 87 octane gas.

@Jeepster1 : I just learned today that Petro Canada are no longer Top Tier. Apparently, companies have to pay to be part of that club, and speculation has it that Petro Canada no longer wanted (needed ?) to pay. They have their own additives, they sell a lot of gas up here and I have never heard of any problems with their gas (nothing major anyways). They merged with Suncor 10 years ago.

I only buy gas from one of the three busiest gas stations in town, either Petro Canada or Shell, so no problem with stale gas. There is 10% ethanol in it though like most (all ?) 87 octane gas.
 

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There likely *was* a problem with mine. These engines, whether it's a 2014 3.2L or any other year, a 3.6L Pentastar... they should not ping with 87 octane gas.

@Jeepster1 : I just learned today that Petro Canada are no longer Top Tier. Apparently, companies have to pay to be part of that club, and speculation has it that Petro Canada no longer wanted (needed ?) to pay. They have their own additives, they sell a lot of gas up here and I have never heard of any problems with their gas (nothing major anyways). They merged with Suncor 10 years ago.

I only buy gas from one of the three busiest gas stations in town, either Petro Canada or Shell, so no problem with stale gas. There is 10% ethanol in it though like most (all ?) 87 octane gas.
But you know the dealer and I am sure they are not changing the additive package in their gas. They are saving by just not paying the toll on Tier1 labeling.
The more important issue is the gas is fresh all the time. You are getting full octane and additive value out of fresh gas. No degraded gas.
No different than packaged oil sitting on the shelf. But again that's a whole different discussion.
 
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Discussion Starter #18
Bringing this back to life. Got some engine knocking again, about one year after the first event. This time, 91 octane alone did not cure it, but a bottle of octane booster calmed it down. Took it back to the dealership ; master tech had a look with wiTECH and saw nothing wrong with cam phasers this time, so he was baffled. I had tried gas from different brands, no change. He then suggested I change the spark plugs, even though I was only at 65K miles ; he took one out to eyeball and said it was ripe. And maybe that was causing the knock... according to him. Same as last year, knocking occured between 1200-1800 rpm under specific engine load conditions / throttle application. Very annoying and ugly noise...

So... they did the plugs (I brought my own Champion Iridiums from Rock Auto ; 1/3 the price of the Mopars here). Tech comes for me in the waiting room to show me something (uh-oh..) : oil leak into one of the spark plug wells. Job just got more lenghty, and costly... Next day, a few hours and gaskets later, I was out the door with new plugs, and still half a tank of boosted 87. A few days later, filled up with 87 : no more knocking. Go figure...
 

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Bringing this back to life. Got some engine knocking again, about one year after the first event. This time, 91 octane alone did not cure it, but a bottle of octane booster calmed it down. Took it back to the dealership ; master tech had a look with wiTECH and saw nothing wrong with cam phasers this time, so he was baffled. I had tried gas from different brands, no change. He then suggested I change the spark plugs, even though I was only at 65K miles ; he took one out to eyeball and said it was ripe. And maybe that was causing the knock... according to him. Same as last year, knocking occured between 1200-1800 rpm under specific engine load conditions / throttle application. Very annoying and ugly noise...

So... they did the plugs (I brought my own Champion Iridiums from Rock Auto ; 1/3 the price of the Mopars here). Tech comes for me in the waiting room to show me something (uh-oh..) : oil leak into one of the spark plug wells. Job just got more lenghty, and costly... Next day, a few hours and gaskets later, I was out the door with new plugs, and still half a tank of boosted 87. A few days later, filled up with 87 : no more knocking. Go figure...
I'm sure you guys are well into winter blend fuel by now too...That never helps either.
 

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If your pinging goes away with using better premium fuel then it very well could be carbon build up on the pistons. But yes we are well into winter gas now which is a killer hell i think there is even a TSB out for poor engine performance while using winter blend gas.

If you halfway know what you are doing i would run a can of seafoam through the motor (great way to piss off your neighbors due to the smoke show it will produce lol)
 
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