I know the 4.0s are noisy engines, but I've got some pretty significant valve chatter. It's a loud rhythmic tapping and sounds louder than my old XJ with the same engine. I also failed smog for NOx levels being too high, which means that it's burning too hot and lean, so the timing is almost certainly off. Anybody know where to start with this? O2 sensor is brand new.
05-19-2013 06:05 PM
Do you change the oil frequently?
Take a look at your plugs and see if they can give you a hint, also check for codes.
05-19-2013 06:34 PM
Oil is changed very regularly. It's a tad low, but frequently changed. Plugs are new too, but I'll see if there are any hints in that department. No codes. Just the normal 12, 33 and 55 codes.