i just pulled off my egr valve to clean it had gotting a check engine code for that tell you i was surprized at the amount of carbon build up inside too about 2 hours of cleaning but thats a differnt story i was waiting on the wife to get ome to run to the store for more thottle body cleaner and so i decided to pull out the plugs and see what they looked like (go figure replace them too) but as i was looking at the top on the pistons threw spark plug hole i noticed that the front 3 were nice and clean bu the rear 3 had a bit of carbon build up just wondering if anyone had ideas on cause of this its a 1996 xj6 with 4.0 non supercharged

thanks in advance

also wow i didnt know it took 8 quarts of oil guy at auto store said hey youd be better off doing this deal then i told him its a jag he said never mind lol

 

I am in the process of replacing head gasket in a '92, 148,000 miles and everything looked very clean until exhaust manifolds removed. Tons of carbon all the way to the end of tailpipe. Also sludge pile where EGR line connected to intake, but not bad in rest of int. manifold and head ports. One senior member advised checking for plugged catalytic's, said it caused enough back pressure to blow his head gasket, FWIW.

 

thanks ill look into that or sure