Engine/Transmission (1994 - 1998) idle changes and lose bottom end

[LVJUNIOR]

I have been having a problem with my idle droping to the point if I have my air on the truck will almost die. Then I get in the truck again and the idle is fine. When the idle drops it also seems to lose all bottom end power and gets smokey as heck below 1900rpm. The truck also does not seem to be responding to tuning the AFC housing or the fuel plate either

 

[LVJUNIOR]

Does it sound like a pump problem? Where is the best place to get a 215 pump?

 

[DieselDoghouse]

It could be a pump problem OR - you mentioned "when the air is on" you near a stall condition…so I'm guessing its also warm/hot outside. I've found DD's idle will drop in hot weather - because of the pressure relief valve on the return line. I guess when things get hotter under the hood the spring gets softer and fuel delivery starts gettin funky (bypasses more fuel??). Problem resolves when it gets 'brisk' outsde. This would account for a dropped idle and bad low end. Its my bad since I've never got around to replacing it with one from someone like PDR. But I might try that first if I were you!

 

[LVJUNIOR]

I have checked the fuel pressure when the idle was bad and the pressure is still good. As far as the heat goes, It ran good with a decent idle on the trip back from barstow last sunday and it was 115 degrees outside. The next day back to crap again

 

[LVJUNIOR]

The other problem i am having is that i can not control the smoke on the bottom end. I can not go over an overpass from a stoplight without blowing enough smoke to get a ticket and even with the smoke it stuggles to do it at all. There is no power at the low end. Injectors have been gone through, fuel pressure is good, fuel lines are new, overflow valve has maybe 12k on it.

 

[JohnBoy5]

turbo maybe???

 

[LVJUNIOR]

it has an industrial injection 62/14 on it and it used to spool about 1400rpm right now I cant light it until 1800rpm. no boost leaks turbo hits 42psi wastegate pretty quickly after 1800rpm

 

[JohnBoy5]

do you think something could be starting to go wrong with the turbo? why the change all the sudden... .

 

[LVJUNIOR]

I have been chasing the tuning on this truck for 2 years and no matter what I do I can not gett better than 13mpg empty and 11. 5 towing 4000#, the EGT's have always been high (I cruise at 1050 degree) And the truck pulls a trailer like a 350 chevy. Lately it has gotten even worse on the bottom end but the bottom end has never been stellar. The turbo has maybee 12,000mi on it

 

[LVJUNIOR]

I think I am going to order a 215 pump today

 

[LVJUNIOR]

215 pump installed and big improvements in pre-boost bottom end performance. the truck seems to pull pretty well with light throttle and it starts instantly and no more stalling at idle. I still have a ton of turbo lag but I haven't changed the AFC spring yet. I also still seem to have to much EGT. Pulling a 6% grade empty (9300#) I am at 1200 degrees running a steady 1900rpm. I still don't know what the mileage is on the new pump yet either