I have a 95 S vin K2500 that has been my project for the last month. It started out as non-op but now runs fantastic and starts with little more than a hiccup of a crank. The only problem is that I have a tiny but steady stream of smoke coming out of the tailpipe even at idle. When I take off it spews out enough smoke to be annoying but nothing compared to when I first got her running.

I have done a lot to what started out as a fully stock truck. Here is a list:

1. New Diamond Eye 4" exhaust with 3" down pipe.
2. New Flight systems PMD with remote bumper mount kit.
3. New LP, LP relay and OPS mod.
4. New filters everywhere, fuel, oil and air.
5. New CDR.
6. New AC Delco Thermostat.
7. New AC Delco fuel injectors and return lines.
8. New AC Delco Glow plugs
9. New vacuum pump, Turbo solenoid and lines.
10. New hoses and belt
11. Resealed oil pan and front timing cover seal.
12. New Hydraulic Brake Booster and Master Brake Cylinder, brakes and complete flush.

There are no codes of any kind ( 12, 12 ) and I test drove another 6.5 over the weekend with a rebuilt motor and mine runs smoother and pulls harder than the one I test drove so the only thing I see as a problem is the smoke.

Just so you are aware, when I first got her running ( before I replaced any parts) I could black out an entire intersection and completely stop traffic when I took off. Now it just spews some black smoke for a couple of seconds before turning into a gray haze and then clearing up.
After all the work I've put into it, is it possible I need to readjust the IP timing or something like that?

 

UPDATE: Well the strangest thing happened today. I think it was a good thing. Because of the smoking, I accelerate a bit slower than the rest of traffic so the guy behind me doesn't get a face full. He still gets quite a bit but not choking.

Well today coming home in heavy traffic I was accelerating closer to normal so traffic wouldn't get it's panties in a bunch. I came up to a light and as usual, it was still smoking at idle. BUT, about half way up to speed, the truck suddenly got a lot stronger with much less throttle. When I came to a stop at the next light I also noticed there was no longer any smoke at idle. Now, it seems to have little if any smoke during acceleration and accelerates with much less throttle. Even under load it is stronger. There is a hill I travel that changes from 45 to 55 about halfway up. I usually push the pedal as far down as I can without causing the truck to downshift. Usually I reach the top of the hill doing about 50 but tonight I had to let off the pedal before I reached the top because I was already doing 60. The only negative I see so far is the idle seems to have more vibration than before.

If anyone has any ideas, I sure would like to hear them. I don't know if it is fixed or this is a prelude to a pending disaster.

Thanks,
Dan

 

it may be the APPS. im not very familiar with the electronic of the 95 6.5 since my 93 is all mechanical. but thinking about logic, since you got yours non-op, maybe there was something on the surface of the contacts inside the APPS, that rubbed away after driving several times. IDK, maybe im crazy???

 

At this point I could believe just about anything. I checked the APP sensor and the connector looked clean, but I didn't test it. I read that the new Ultra Low Sulphur Diesel is pretty bad for our motors. After some research I found that adding a gallon of B20 each fill-up increases lubrication to the system better than most any additive. It definitely makes the motor noticeably quieter at idle. I also heard it can free up sticky injectors and such. Even though I've replaced the injectors, I was wondering if ULSD can cause sticking in the IP? I've gone through about 8 Tanks with B20 added in the last month, maybe it fixed something that was stuck or gunked? IDK, just throwing it out there.