I have a 1988 RD690S With a EM6275L engine was having low power black smoke and high pyro temps, took it to Mack dealer they found a crack in the charge air cooler and said turbo wasn`t working like it should so they replaced it. The truck runs alot better but seems like it has turbo lag. when pulling a hill it doesn`t have the power it use to have. I have changed the air filter and fuel filters and checked the fuel pressure 40psi and checked all the hoses. injectors have been pop tested and all is good, pump rebuilt not long ago. the pyro is where it should be but to me it is smoking more than it use too not real black smoke but dark. anybody have any idea`s what we are over looking? I just dont want to throw parts at it, also this truck doesn`t have a puff limiter it has the robert bosch pump with lda valve and it has a brass fitting coming out of the intake where a puff limiter would be,it has an air line going through it and goes to the lda valve on injection pump, i took air line loose and sucked on the line to see if diaphram in pump is ok. I took the fitting out and it has a spring and ball in it i cleaned it and put it back in. any suggestions would be greatly appreciated.