Patriot Engine Knocking: Fix Revealed Before Shop Visit

As someone with moderate experience working on cars, I faced nearly identical issues with my 2015 Jeep Compass. The symptoms were exactly as you describe, power loss, jerking, and smoke, along with knock sensor warnings. After taking it to my regular workshop, they diagnosed deposits in the combustion chamber causing pre-ignition problems. The build-up was affecting proper fuel combustion and causing the knock sensor to detect irregular detonation. The fix involved: Thorough combustion chamber cleaning, Adjusting the engine timing, Replacing the knock sensor as a precaution, Engine tuning to optimize fuel mixture Total cost was 425 Euro and resolved all symptoms. The mechanic mentioned using higher fuel octane rating could help prevent future build-up. To provide more specific advice for your case, could you share: Current mileage, Fuel type you typically use, When symptoms first appeared, Any recent maintenance performed, Check engine codes if you have them These details would help determine if your Patriot is facing the same issue mine had.

Last service completed 3 months ago at 171500 KM. Since then, Ive monitored the piston slap noise carefully. The shop adjusted ignition timing and cleaned injectors during that visit, but the detonation issue persists even after switching to premium fuel. A cylinder leak test showed chamber 2 and 4 have slightly lower compression than spec. Looking to get a second opinion before proceeding with more invasive repairs.

Thanks for those details. Your symptoms match exactly what I experienced with my Compass before the full repair. The fact that the issue persists after ignition timing adjustment and injector cleaning points to a deeper problem, just like in my case. The compression test results from cylinders 2 and 4 are telling. When my Compass showed similar compression variations, it ended up being carbon deposits affecting the cylinder heads and combustion chamber sealing. The pre-ignition issues continued even with premium fuel until we addressed the root cause. After my initial repair mentioned above, I had to go back for: Cylinder head inspection and resurfacing, Valve seat reconditioning, New head gasket installation This more extensive work cost 1100 Euro but completely resolved the knocking and compression issues. The engine tuning performed afterward ensured everything worked in harmony. My suggestion would be requesting a borescope inspection of those low-compression cylinders. This will reveal if you are dealing with similar carbon buildup or possibly valve seating problems before committing to major repairs.

The knock sensor issue combined with low compression in cylinders 2 and 4 definitely points toward something more serious than just timing or fuel quality. After hearing about your Compass repair experience, it makes sense why our initial service attempts didnt solve the problem. The fact that premium fuel and timing adjustments havent helped suggests deeper mechanical issues affecting combustion. The pre-ignition symptoms match what you described, especially considering the persistent piston slap noise Ive been monitoring. Given the mileage on my Patriot and the compression test results, pursuing the borescope inspection seems like the logical next step. While I was hoping to avoid major repairs, addressing potential cylinder head problems now could prevent more expensive damage later. Ill schedule an inspection at another shop and request they specifically check for carbon buildup and valve seating issues. The repair cost you mentioned gives me a realistic budget to plan for. Thanks for sharing your detailed repair experience, it helped confirm my suspicions about needing more extensive work beyond basic maintenance.