Hey got a 2000 xj that I've been tinkering with off and on for few months now. I got a CEL a few months back for cylinder misfire. I put new plugs, coil pack and a crank position sensor in and the CEL is gone now. It idles fine but when you go to drive it the thing starts acting up and under heavy acceleration I get a flashing CEL but when i go to check what it is on my scanner nothing shows up. I'm starting to run out of ideas. Any ideas?

 

Flashing CEL typically means a multi-cylinder misfire is being detected.

Multi-cyclinder misfire that presents under acceleration and as RPMs increase, but without the presence of a check-engine light, is a hallmark of a failing crankshaft position or an aftermarket crankshaft position sensor that is not producing the correct signal as RPMs increase. This is not the only thing that can cause your symptoms, but it is a common thing.

Here is the same problem on video (2000 XJ as well):