Cylinder 8 injector threw a max limit code. So I replaced the injector with a bosh reman injector. After replacement that cylinder started knocking at idle. I had a friend put injector code in computer for the relearn. Drove it a little bit still knocking at idle. I pulled the injector just in case the copper washer didn't seal and used a new hold down bolt also. But its still knocking. The old injector did not knock at all. So I'm beginning to believe this bosh reman injector is bad. No I have not checked compression but I do not have any blow by when I pull oil cap. The truck is comp lately stock with 280k on the clock. If any one has any suggestion that would help let me know. my next step will be reinstalling old one and taking reman back to autozone.