My 2002 WJ Grand Cherokee 2.7 CRD 89000 miles - has a strange "misfire". Basically the engine starts first time and idles smoothly and would continue to run that way until any throttle is applied. When throttle is applied the engine randomly misses and shakes, releasing the throttle the engine goes back to idle but misfiring and shaking. Switching off and restarting, the idle is smooth. Car drives, but with very much reduced power when cold, so much so, that it won't pull away until its been running for 30 secs. or so. When driving, it accelerates but with a fair amount of "clatter". At the point where the engine is neither accelerating or decellerating, the "misfire" is really obvious. Putting on more throttle cures the misfire, and applying even more throttle it pulls like a train without any obvious misfire or shaking. The car returns 35 mpg on a motorway run. I've changed the fuel filter and checked all the feed and return lines for leaks. I've also purged for air at the bleed port - nothing present but clean fuel - no bubbles present. I've disconnected each injector in turn which causes a severe regular misfire on each cylinder. My basic code reader connected to the OBD port says no faults stored. Any suggestions most welcome.......
