I have a low compression on cylinder 4 for making the check engine light come on every 50 - 100 miles when driving then I clear the code and then it comes back on within that a 50 to 100 mile range. The car has a relatively low miles it has 102,000 miles on it. (98 xjr.) I have a feeling that I have carbon buildup around the piston rings, causing the low compression. I also tried to pour oil in the chamber to see if the compression reading goes up and it did. When driving the vehicle, I experience a vibration, when on the throttle at low to high speeds it’s not very noticeable, but you could definitely feel it, and it’s pretty sluggish when your floor it from a dead stop compared to my other xjr.I am thinking of soaking each and every piston ring in the combustion chamber with a chemical called Chem dip from my local auto parts store. People on YouTube use it to soak their piston rings to remove carbon buildup. Do you think that it would be a good idea to try it out before ripping out the engine and possibly putting a new engine or possibly LS swapping it.

 

What is the compression numbers for all 4 on that same bank?