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View Full Version : On another note, I'm still getting smoke.


lmwatbullrun
07-24-2010, 01:42 PM
I'd appreciate comments on this-

I let the engine idle for at least 5 minutes before I drive it. Very little smoke on start, now that I have spent 2000 miles with various injector cleaning regimens (Lubromoly, ATF, DieselKleen, etc.) Big improvement except for two areas where I still get smoke.

I get gray smoke at low revs, after I have been idling for a couple minutes, such as when I accelerate away from a long stoplight, whether the engine is has been driven a while or not, which I am attributing to fried valve stem seals. (They are 25 years old, after all) Doesn't seem to matter whether the engine's been running for 5 minutes or 5 hours, I get gray smoke after I idle for a while. This can be mitigated somewhat by easing the throttle open; this seems to spread the smoke out and reduce the overall volume somewhat. (I am guessing that the engine is better able to burn the lube oil in that instance) I will probably rebuild a head in the near future to deal with this problem, but would like comments/opinions on my diagnosis before I proceed.

Then, as I continue to accelerate, I start to get black smoke, which seems to come in puffs, from the exhaust. It is notably worse at higher RPM, especially at around 3000 RPM. Rate of acceleration makes a difference, but even just cruising at 3000 rpm, I'm getting black smoke. If I can accelerate slowly, the emissions are much reduced, but not eliminated. This problem is noticeably worse when I have just started driving, and is almost unnoticeable but still present once I have been driving for 1/2 hour or so. I have also had several occasions when this has NOT occurred, and the car appears to have a slight increase in power, too. I do seem to get slightly less smoke generally when I run certain brands of fuel with a higher cetane rating.

I am thinking that this could be several things-
-A diddled with injection pump that is putting out too much fuel under boost. (how does one adjust such a thing?)
-Leaky/fouled nozzles/injectors.
-A control function that is not working/connected properly.
- Bad fuel?
-Something else? (possibly soot being vibrated out of the exhaust from prior problems?)
- A combination of these issues.

I'd welcome comments/suggestions. Right now I am leaning slightly towards replacing the injectors, which have almost certainly never been replaced in over 150K miles/25 years, but would like to have a more definitive diagnosis before operating. Now, keep in mind that when I started driving this beast, I had significantly more smoke than I am seeing now; this is a huge improvement, but still annoying for those behind me and still wasteful of fuel; I'm getting about 29 mpg for a good highway speed 60 mile trip up from 23/24 when I started, and I'd like to get 35, which I think is feasible based on what I have heard.

Thoughts?

On another note, the turbo seems to be spinning faster when I am traveling at highway speeds and ease OFF the throttle; I hear the turbo whine speed up. Is this normal?

Jason
07-24-2010, 02:50 PM
Well the turbo spooling up when you let off doesn't make any sense... As far as injectors, nozzles aren't that expensive and since it sounds like your pretty handy, I would be you could build an injector pop tester if you don't already have one or cant find one for sale. I would just replace them so that takes them out of the equation as a possible problem. For that matter, there could be a loose injector thats not firing well, you should check the torque on all of them in the mean time. I have had them come loose on more than one occasion even after being torqued at the correct value using new injector heat shields. The smoke on take off sounds like valve stem seals, though it could just be worn piston rings and the engine is "loading up" with oil so to speak. As for black smoke, your fuel pump may have been turned up, and the AFC housing may have been adjusted. The afc housing is on top of the fuel pump, there is a alen head screw with a 12 or 13mm jamb nut on it. Loosen the jamb nut, and back the screw all the way out. I would bet you'll find that its burried all the way in and not sticking up through the nut at all. After that, I would buy a boost gauge to see what the turbo is doing when you getting the black smoke, if boost is staying consistant, how much your running etc... It should be no more than a haze at wide open throttle at full boost if the fueling hasn't been adjusted. Stock boost is around 8 to 10 psi. If your getting that much boost and still have smoke, then you either need to turn the boost up, or back the fueling off by turning the main fuel screw out. Take a look in the performance section, there is a write up on pump adjustments, if your trying to get less smoke and closer to stock, just do the opposite of what the write up suggests!

Hope this is helpful.
Jason

lmwatbullrun
07-25-2010, 03:35 AM
Sounds more like somebody has installed the timing belt a tooth off.

Well I suppose that is possible, but since I checked the pump timing when I replaced both of the timing belts a couple weeks ago, and rechecked it yesterday when I replaced the cam seal per the green book, and it was spot on spec (0.85 mm advance), with the flywheel TDC mark and the pump pulley mark in agreement, I'm ruling that out for now. I did look to see what a tooth off looked like and it was a noticeable mismatch between the flywheel and the pump marks.

lmwatbullrun
07-25-2010, 04:04 AM
Well the turbo spooling up when you let off doesn't make any sense... As far as injectors, nozzles aren't that expensive and since it sounds like your pretty handy, I would be you could build an injector pop tester if you don't already have one or cant find one for sale.

I have my eye on one; it's been on my list for some time now and I need to bite the bullet and either spend the time or the money to do this correctly.


I would just replace them so that takes them out of the equation as a possible problem. For that matter, there could be a loose injector thats not firing well, you should check the torque on all of them in the mean time. I have had them come loose on more than one occasion even after being torqued at the correct value using new injector heat shields.

Will check injector torque and report back. Any suggestions on nozzle sources? also, injector shims? Which nozzles are best for sea level driving in the eastern US?


The smoke on take off sounds like valve stem seals, though it could just be worn piston rings and the engine is "loading up" with oil so to speak.
I'll start with the head and go from there. I may well end up rebuilding one of the spare engines I have on hand.


As for black smoke, your fuel pump may have been turned up, and the AFC housing may have been adjusted. The afc housing is on top of the fuel pump, there is a alen head screw with a 12 or 13mm jamb nut on it. Loosen the jamb nut, and back the screw all the way out. I would bet you'll find that its buried all the way in and not sticking up through the nut at all.
Yup, that is the present condition of that puppy. Will modify and advise.


After that, I would buy a boost gauge to see what the turbo is doing when you getting the black smoke, if boost is staying consistant, how much your running etc... It should be no more than a haze at wide open throttle at full boost if the fueling hasn't been adjusted. Stock boost is around 8 to 10 psi. If your getting that much boost and still have smoke, then you either need to turn the boost up, or back the fueling off by turning the main fuel screw out. Take a look in the performance section, there is a write up on pump adjustments, if your trying to get less smoke and closer to stock, just do the opposite of what the write up suggests!

Hope this is helpful.
Jason

Most helpful! Many thanks!

Jason
07-25-2010, 06:42 AM
For nozzles, you can spend more and get the monark nozzles, George bought a set of them (v8volvo) and put a post up of his results, I think he listed who he bought them from. I bought the ones from the cheapo diesel parts place I have listed in the parts supplier's section, i think its volkswaparts.com. Autohaus had nozzles listed about a year ago, but I think they closed them out and quit carrying them. The nozzles I got are the chinese ones, but the quality was good and the price was right. Will they last 150k miles? Who knows, but I didn't have a bunch of money to blow at that time, and they did show a noticable improvement. Also they are the copy of the DNOSD273 which is the European "GTD" nozzle. As for shims, mercedessource sells a kit, though its not cheap. I scrouged around local vw shops and bought up core diesel injectors and took them all apart and made my own set. Between the shims that come out of your injectors, and if you can find any others you should be able to get a set built within pop pressure spec.

Jason

lmwatbullrun
07-28-2010, 03:05 PM
any thought on the Bosio nozzles?

Jason
07-28-2010, 04:00 PM
I've never seen those for a IDI diesel, only the TDI. Sure you read the descriptions right? On that note, they are good nozzles I know many people with TDIs run them.

Jason

piper109
07-31-2010, 06:59 PM
[QUOTE= As for black smoke, your fuel pump may have been turned up, and the AFC housing may have been adjusted. The afc housing is on top of the fuel pump, there is a alen head screw with a 12 or 13mm jamb nut on it. Loosen the jamb nut, and back the screw all the way out. I would bet you'll find that its burried all the way in and not sticking up through the nut at all. After that, I would buy a boost gauge to see what the turbo is doing when you getting the black smoke, if boost is staying consistant, how much your running etc... It should be no more than a haze at wide open throttle at full boost if the fueling hasn't been adjusted. Stock boost is around 8 to 10 psi. If your getting that much boost and still have smoke, then you either need to turn the boost up, or back the fueling off by turning the main fuel screw out. Take a look in the performance section, there is a write up on pump adjustments, if your trying to get less smoke and closer to stock, just do the opposite of what the write up suggests!

Hope this is helpful.
Jason[/QUOTE]
If there is black smoke before the turbo spools up, this can be reduced by raising the Allen screw as mentioned as it controls the amount of fuel before the diaphragm is moved. If however the smoke occurs on acceleration, one of the ways this can be controlled is by rotating the pin that is attached to the diaphragm underneath that top cover to a position with a shallower taper. The pin is attached to the diaphragm so by rotating the diaphragm one rotates the pin.
I do not believe you can reduce the amount of smoke produced during acceleration by raising the allen screw on the top...unless the turbo is not working...because as soon as the diaphragm is deflected by the boost pressure, this screw touches nothing.
Much more effective in reducing smoke during acceleration with boost pressure is to rotate the diaphragm. I would suggest rotating it anti clockwise 30 degrees at a time to see how it reacts, after marking the diaphragm position before you start.
Basic bottom line expressed slightly differently is that the black smoke is a product of too much fuel for the amount of intake air present. The excess smoke is just fuel being wasted.
To make the smoke go away either the amount of air needs to be increased or the amount of fuel decreased. Having components in dubious condition will complicate and confuse the tuning process however so all disclaimers apply ;-)

Steve

lmwatbullrun
08-03-2010, 04:48 PM
MOved the diaphragm screw all the way up and this did reduce the smoke load on acceleration somewhat, but I still have smoke on hard accel. It's more evenly distributed now, not so puffy. I'll look and see whether someone goobered with the pump settings. It is funny, but sometimes, especially when the engine has been running very hard for some time, I have no smoke problem at all. Other times.....:confused:

Jason
08-03-2010, 05:55 PM
How much boost are you running? Is the turbo light comming on? In my car, my waste gate was bad so the boost dump valve would open and dump boost, problem was its not made to regulate boost like a waste gate, just as a fail safe. I would get right up to about 10 or 11lbs and once the valve poped open it would drop to 8 or so. You could be loosing air that way, but I would install a boost gauge first. I plugged mine and it ran pretty good, untill I installed the boost gauge and figured out my waste gate was bad. I'm suprised I didn't blow the head off. It was pushing way over 20lbs of boost and climbing so I let off, I don't even know how high it got...

Jason