throttle is slow to return to idle after pedal is released. pretty bad in town with stoplights. i bought the truck used 2 years ago and always has has this issue along with heavy black smoke on acceleration, but runs fantastic except rough at 50-55mph it is auto with 125k
thanks!

 

Do you have a rail pressure gauge? Sounds like your FCA may be on its way out.

 

thanks for the reply, the pressure was checked and was in spec. the shop suggested someone may have installed performance injectors and a bigger turbo might help...

 

Is the shop a diesel shop? There are several people who run Overstzed injectors/performance injectors and do not have fluttering or slow throttle return. Was the balance rate checked on them as well? Could be sticky injector if rail pressure is in check. I have 100hp injectors on my truck and when I let off the throttle there is no sticking throttle/flutter. I'd get a second opinion before buying a turbo- turbo will help produce more air=less smoke

 

the shop performs alot of diesel work and locally pretty highly regarded. we are a small logging town in Idaho. i thought the rough 50-55mph zone was a u joint or converter. but after pulling driveline, narrowed it to tngine. it runs great under load and really quiets down. my nephews 2008 chipped 6.7 cummins comes close in streetlight challenge. i know a lot of fuel has to be injected as the black cloud is huge. i just found out the injectors were changed before i bought the truck as the previous owner didnt change fuel filter and burnt injectors.. does that sound right? i have worked on tractors/equipment with mechanical systems but not up to speed on theCR systems... no codes have appeared. thx!

 

if there is a lot of black smoke then tuning/turbo can help clean that up. The stock filtration is not as good as it should be. A 10 micron filter (stock) will kill injectors over time for sure that's why a lot of guys including myself upgrade to fass/air dog to protect their injectors (2 micron). I would ask if they can check injector balance rates for you. It's a quick plug in the obd2 and it'll give you a number for each. Anything -/+ 4% is out of spec. An injector continuing to dump fuel after commanded not to is called injector hang and is an issue. You can YouTube it to see if you have similar symptoms.

injectors are sold reman which is basically used and then new. Both fail even when purchased new- remans especially fail often shortly after install due to the used components so someone saying they have "new" injectors may just mean new to them and they are remans. Remans are simply flow tested before being resold.

Your saying the injectors were replaced before you bought the truck due to poor filtration I guess?

 

i appreciate the advice and will have thebalance checked. who makes a small micron filter? wix-napa and numbers if possible.
Larry

 

5 micron . Wix is a 7 micron I believe. If you don't want to do a whole lift pump CAT makes and inline kit with water seperater and fuel filter that's relatively inexpensive. Those filters you can run much longer than the stock bowl setup. The FASS filters are 25k miles- I used to swap my wix out every other oil change about 12k miles

 

after a break, i'm back with same issue... another 7k miles and no change. I cleaned and checked apps, cleaned ground wires, reinstalled stock program, round trip to AZ at 17 mpg.
I think tc is going as i feel a shudder under hard acceleration. still breaks tires loose at 55mph and black cloud is huge. still leaning to injectors.. when sitting in park, i can hit throttle hard to 3000 rpm- release- revs to 3300rpm and stays for several seconds. HELP!