My problem is that I can't seem to get rid of it, I tried turning back the fuel, but to no avail.

The truck has a non wastgated turbocharger (ATS 088), and it runs very well with plenty of power, except for the smoke.

If I baby it, its fine, but as soon as I give enough throttle to push the boost past 5 psi, it starts to smoke, any more above that, and there is even more (maxes out at 7-10 psi). My reading of other's experience with turbocharging these engines, is that the the smoke actually drops off after passing 5 psi. Would any of you care to weigh in on this???

It starts up very easy on a cold or hot start even with two dead glow plugs, so I thinking its not a return line or compression issue.

Could a return line leak even have any affect once driving up to speed??

I also found two mild exhaust leaks at the crossover pipe, but fixing them had almost no affect.

Could a leaking injector cause this? Any other Ideas?

 

Mine really doesn't clean up until I get to about 10 psi, but, I am dumping lots of fuel, so, pretty much, below 2000, any kind of enthusastic throttle use has me pouring black...
You should have been able to get yours to clean up by backing the screw off. I wonder if you don't have a timing issue?

 

Too advanced timing will cause black smoke.......

 

It was slightly too retarded, so I used the standard timing by ear method, and it still drives well, but there was no affect on the amount of smoke before or after the timing.

Mine NEVER cleans up, the amount of smoke is proportional to the weight of my foot. It increaces gradually, and most of the time 7 psi is all the boost I get with it floored, though more is possible with higher revs.

Its a little frustrating, because by the time I'm halfway to the floor, there is already enough smoke to make me want to back off. I have modified the truck for MPG not power, but I doubt I'm getting all that I can with this condition.

 

Is your air filter clogged up? I would think that an intake restriction like that would cause an overfueling giving you lots of smoke and increasing as you gave more pedal.

 

The truck has a K&N filfer that is less that 5k old, and its not very dusty where I live.

 

What is the code on your injectors?? Is this another case of 7.3 G code pushing too much fuel for a 6.9.

 

Didn't think that would matter much since I have a turbo, but I have a recent sett of code D injectors. The truck came with a set of Code BB injectors, but had to replace tham when a misfire at cold start developed. Other than that, there was no difference in performance that I could tell between the two sets.

This ones got me stumped guys, any ideas you might have, I would like to hear, doesn't matter how crazy it might be.

 

You are on the right track. It is basic engine. If you have black smoke then you don't have the right air fuel mixure. You are short on air or oxygen is the important part. If it is timing then it sounds more like retarded then advanced. Generally if you advance a motor up and are throwing the fuel to it they will generally will have a white to gray smoke and be real fumy at an idle and once you crack it it will get black but a real retarded engine with more then enough fuel will generally idle black. Generally. There is always exceptions.
Do you have an intercooler. I am wondering if your are intake temp is to hot which can cause this.

I noticed that you have an overdrive trans with 3.08's. That thing needs wings. I drove an 83 with 3.07's and it smoked black pretty good too. I figured that since the engine really didn't get run a higher rpm because of the gears that it could have been "loading up" on fuel in the cylinders. Basicly sooting up. I know the exhaust was sooted up bad. I replaced the muffler because it had a hole in it and smoke cleared up alot for awhile.
Just a thought.

 

Do you figure its worth advancing the timing a bit more?

I understand what you're saying about the low revs, at 55mph, its barely turning over 1200rpm, but I feed it only enough to keep it going at those speeds (barely more than idle), the slightest hill or other load, and I will drop it out of overdrive (at those speeds, its more of a novelty than anything else).

Whats frustrating though, is that even if I go all the way to second gear at 55mph, the smoke is still there, anything above half throttle (about 5 psi of boost) and the smoke only gets thicker.

Even above 70 mph, I will at least unlock the TC at the hills, which puts the revs to 2000rpm, and I can go even further by dropping to 3rd with the TC still unlocked, now I'm aproaching 2500. But even at 2500, the tailpipe will not clear, and the most boost I get is 8 psi. I have seen more boost, with the fuel turned up (12 psi), but its not a pretty sight for some one behind me......which is why I turned the fuel down.

The truck also has a ram intake, not pretty, but does the job.

The exhaust at idle is fairly clean, grey-white smoke visible only in direct sunlight at the right angle.

I'm not sure if this really matters, but I noticed that the smell is different from the other two diesels in the family. Not that I normally go around snorting diesel fumes, but my dads 6.5 turbo and my sisters ranger (2.3L Mitsu turbo) both have almost a sour scent to them, but mine has a rich diesel smell, as in diesel exhaust, not diesel fuel.

 

Leaking or slobbering injectors (depending on how bad) will cause a miss, white smoke with a rich, raw fuel smell. Raw fuel will also come out the exhaust in tiny droplets.

You should be blowing black smoke only on hard acceleration (up to the point when you start getting good boost) or a puff of black when shifting, then clean up to mostly heat waves. Of course lugging the engine is going to make lots of black smoke.

According to your posts, you do not have clogged intake, you are getting good boost, no miss, fairly new injectors, you have changed IP timing. To me, it points to over fueling. Either the IP is just turned up way to far or there is something wrong internally with the IP.

There are 2 inherent problems with the older IP's. The plastic coupler starts to come apart and the fuel advance wears a bunch. Both are internal problems. The higher the milage on the IP, the more internal wear on other parts also. Most "rebuilt" IP's do not address the other wear problems other than the coupler and advance.

 

I'm a little reluctant to turn the fuel down even more, since 7 psi is the most boost I can see normally, as I said before, it can do nearly twice that, but not without the smoke.

I tend to accellerate smoothly to avoid the initial smoke puff that comes with tromping in it.

However, every now and the, there is small smoke puff if I am ramping up for a hill, or on the onramp. Its not tied to shifting, it just seems to do this on mild accelleration, there is only one puff, then its gone, and there is not feel of misfire.

 

It would be nice to what the timing is actually at. I am not big on advancing pumps farther then they need to be because of the damage that it will do to the engine and it can make them seem sweeter but you don't gain all the HP that some people think you actually do. I have proven this to myself on a dino to many times.
You haven't had this engine apart have you? As far as milling the deck or heads. That isn't something I will do unless it is absolutely a must because that is something that must be figured in when setting the timing on the pump if you what the fuel timing dead on.
I was going to buy a pulse adaptor for my timing light but I haven't ever done it. I need too though.
And some motors that have alot of miles or hours on them don't burn clean either. I think it is because they get so carboned up on the valves,pistons, chambers wether precombustion or turbulance that they don't get the right air fuel mix in the cylinders because the air isn't moving right. The "swirl" gets out of wack. Just a therory.
This makes two trucks with airplane gears that liked to black smoke alot.

 

I have no way of knowing if this engine has ever been apart, but my guess is that it is original.

I know that bad timing can do bad things to these engines, when I put the new injectors in, it rattled like crazy, till I backed it off.

The best I can do for timing right now is by ear. The only time there is a rattle is for the first 5 seconds of a cold start, and yes, the automatic advance does work. My guess is that I could get away with slightly more advance, and I may just try that.

As far as airplane gears goes, the truck came with 4.10s, and though I only had it for a few months before I knew they had to go, it did not really burn much cleaner, but it was N/A back then.

But 1500 isn't too low for around town is it (The peak torque is at 1400)? And the TC slip means that if I tromp on it, the revs jump to 2000 before there is even a donwshift. As I montioned before, my dad has a 6.5turbo, and it does the same rpm at 50 mph without problems.

 

David85....the very first thing I would check on your truck is the temperature of the top radiator hose.......it needs to get to and Maintain a temperature of 190-195°F under all driving conditions........second is the fuel pressure at the filter at idle and up to running rpms......
Now a question, please do not take this the wrong way, how do you know the cold start advance is working?
crossbones