Engine Spark Knock/Ping <5,000 Miles!!

[dstrahm]

I’ve seen a few threads talking about a problem with engine spark knock but haven’t yet seen a validated fix from Jeep. I’ve worked in gasoline engines since the 70’s and would be hard pressed to accept the FCA mechanic’s answer of “it’s normal, just ignore it” that one poster got. I’d be tempted to make the mechanic’s teeth knock.

Has anyone that has dealt with FCA on this issue ever gotten a workable resolution to the knock/ping problem?
FYI- don’t recommend higher octane fuel. If it won’t run properly at near sea level on the grade they tell me to use, it’s a problem. Thanks.

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[JimLee]

Might as well trade it in now because it's not going away.

 

[Heimkehr]

I’ve seen a few threads talking about a problem with engine spark knock but haven’t yet seen a validated fix from Jeep.

Has anyone that has dealt with FCA on this issue ever gotten a workable resolution to the knock/ping problem?

Possibly related:
When it was just a few months old, my YJ's 2.5L began to sound not unlike a diesel when idling; this was especially evident during cold starts in the morning. The issue manifested itself as a distinct knock.

The problem was diagnosed as piston slap (incorrect cylinder boring), with the remedy being short block replacement under warranty. When the problem reoccurred a little while later, I lost faith in the vehicle and sold it back to Jeep.

I don't know if "spark knock" is similar here, but good luck to those who have to resolve it on their Jeeps.

 

[DaltonGang]

I know you dont like the "Higher Octane" thought, but try it. Every once and a while I also put some injection cleaner in, as well as every once and a while, I put some 93 octane in it. It seems to take the knock out of the engine for a while.

 

[dstrahm]

Possibly related:
When it was just a few months old, my YJ's 2.5L began to sound not unlike a diesel when idling; this was especially evident during cold starts in the morning. The issue manifested itself as a distinct knock.

The problem was diagnosed as piston slap (incorrect cylinder boring), with the remedy being short block replacement under warranty. When the problem reoccurred a little while later, I lost faith in the vehicle and sold it back to Jeep.

I don't know if "spark knock" is similar here, but good luck to those who have to resolve it on their Jeeps.

similar symptom (the spark knock/ping sound is also piston slap) but caused by preignition at the spark plug (timing too far advanced) or igniting somewhere other than the spark plug (the two flame fronts collide) causing a rapid change in the tilt of the piston in the cylinder near top dead center. This causes the piston skirt (bottom edge) to”slap” the other side of the cylinder wall. Never heard of an overbore from the factory!

 

[dstrahm]

I know you dont like the "Higher Octane" thought, but try it. Every once and a while I also put some injection cleaner in, as well as every once and a while, I put some 93 octane in it. It seems to take the knock out of the engine for a while.

Not sure Jeep would agree to reimburse me the cost difference between the specified 87 octane and whatever was required to stop it from knocking.?

 

[Carolina Jeeper]

similar symptom (the spark knock/ping sound is also piston slap) but caused by preignition at the spark plug (timing too far advanced) or igniting somewhere other than the spark plug (the two flame fronts collide) causing a rapid change in the tilt of the piston in the cylinder near top dead center. This causes the piston skirt (bottom edge) to”slap” the other side of the cylinder wall. Never heard of an overbore from the factory!

I'll buy that since the 3.6 has 11.3 : 1 compression ratio. That combined with that crappy gas they sell today. I'm also convinced that the piston to bore clearances in our engines are too loose. It's usually a quality control issue. Randomly smaller pistons are installed in slightly larger cylinder bores. Just my personal opinion based on experiences building engines.

 

[OBD]

I have no idea about your engine....but having ridden and maintained Harley engines for years, detonation is never a good thing. The course of action on a bike would be to back some timing out,richen the fuel mixture,reduce the load on the motor,slow the burn rate of the fuel,and look at the heat range of the plugs.Never heard piston slap that sounded like detonation though. JMO.........

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