Need advice about spark knock

[The_Captain]

Fellow Oil brothers and sisters,

I have a 2017 Jeep Wrangler unlimited. It is equipped with an automatic and 3.21 rear end . The problem is I have spark knock (rattle) when I accelerate or accelerate on hill. It doesn't do it all the time but it happens fairly often. I have tried various fuel treatments and different octane fuels from different top tier stations. It seems to not do it as much when I use 89 or 93 octane. The dealership states they can't recreate the issue. The next time I go in for service I will see if I can get a tech to go along for a ride. It has not thrown any codes. The vehicle has just under 14,000 miles. It has done it the entire time I have owned it. Any thoughts? Guess on what the issue may be? I appreciate any tips or advice. Thanks

 

[KJSmith]

Contact whatever manufacturer that owns them this week and start a file.
They can put monitors on it and see what's happening.

 

[BrocLuno]

It's to new to have manually adjustable timing settings. But my guess is the knock sensor is not right, or the ECU is not seeing the signal, etc.

A little bit now and then is OK, and it indicates that you are running as close to the edge as possible - good for fuel economy. But if it's persistent, that is bad ...

 

[OVERKILL]

There may be a PCM update for this to rectify it. There was for the 6.4L in the GC.

 

[BlueOvalFitter]

Originally Posted By: The_Captain
Fellow Oil brothers and sisters,

I have a 2017 Jeep Wrangler unlimited. It is equipped with an automatic and 3.21 rear end . The problem is I have spark knock (rattle) when I accelerate or accelerate on hill. It doesn't do it all the time but it happens fairly often. I have tried various fuel treatments and different octane fuels from different top tier stations. It seems to not do it as much when I use 89 or 93 octane. The dealership states they can't recreate the issue. The next time I go in for service I will see if I can get a tech to go along for a ride. It has not thrown any codes. The vehicle has just under 14,000 miles. It has done it the entire time I have owned it. Any thoughts? Guess on what the issue may be? I appreciate any tips or advice. Thanks

WOW, what you described here in your post is exactly what happened to my current truck, in 2008.
I bought my 07 F150 new off of the lot with 6 miles on it. From about 7-8K miles the engine would knock, detonate, ping very heavily upon acceleration, or climbing hills. It sounded like 10 wood peckers on a street light! At 14K miles I brought it to the dealer. They could recreate the problem but couldn't figure out why. Finally, the shop foreman told the tech. to look at the piston crowns with a bore scope. Sure enough, HUGE amounts of carbon on the piston crowns.
They kept my truck for 2 weeks. They provided a rental, FREE of charge. A Ford engineer was called in to figure out what was wrong. The PCV system was allowing copious amounts of oil into the intake manifolds, going directly into the cylinders. The engineer figured it out and all was good. But, the WHOLE top end of my engine had to come apart to clean the piston crowns. They were cleaned with some kind of buffer wheel. The intakes were cleaned in parts tanks. They held up the intakes and oil literally poured out from them!
After physically cleaning everything, the tech. put the top end back together. He hooked up a BG Air Intake Cleaning device to my engine. The tech. then ran a few cans of BG cleaning solution thru the engine until he was satisfied EVERYTHING was clean.
My truck has run fine since. I guess you can say a catch can would have helped in this situation.

 

[benjy]

like the girlfriends 08 suby legacy 2.5 + 4 spd auto, it pinged on any grade + got poor MPG's, easy cure was dump it after less than a year. she wanted a subie for a while but that cured her!!! VW jetta 5 cyl 2.5L 6 spd automatic replace it, a good car with great MPG's!!

 

[das_peikko]

Originally Posted By: BlueOvalFitter
The PCV system was allowing copious amounts of oil into the intake manifolds, going directly into the cylinders. The engineer figured it out and all was good.


I wish we knew what the engineer figured out as being the cause.

 

[The_Captain]

Any other thoughts or suggestions?