Exhaust and smoke

J

JohnVanner

Member
I know a bunch of people have talked about this before, but it seems like my 93 Chamonix is making excessive smoke. I know all about the turbo spooling effect which seems to omit puffs at certain RPM levels, but mine pretty much Bellows black smoke every time there’s any kind of stress on the engine. I’m talking about even the slightest incline at any RPM level and black smoke is just pouring from the exhaust. I don’t know if this is normal or not, But I would love for someone to chime in with some info.
 
Black smoke is burning fuel. What speed, RPM, gear (auto or manual), how much fuel are you asking for, and kind of incline are you going up? For instance, if you said something like....
  • When driving up a 10-15% steep 500ft high hill at 25 mph, in 2nd gear on my automatic transmission, at around 2,000 rpm I'm putting out a TON of black smoke, when I put the pedal to the floor to get up the hill.
Vs...
  • When driving up a normal 30ft on-ramp at 45 mph, in 3nd gear on my automatic transmission(Over drive hasn't kicked it), at around 3,000 rpm I'm putting out a TON of black smoke, when I have the pedal about midway to the floor.
That way, is it your foot, or is your injection pump over fueling?

Also, do you have an exhaust gas temperature gauge? If so, what temperatures are you seeing on it, and where is it mounted?
 
sck_nogas said:
Black smoke is burning fuel. What speed, RPM, gear (auto or manual), how much fuel are you asking for, and kind of incline are you going up? For instance, if you said something like....
  • When driving up a 10-15% steep 500ft high hill at 25 mph, in 2nd gear on my automatic transmission, at around 2,000 rpm I'm putting out a TON of black smoke, when I put the pedal to the floor to get up the hill.
Vs...
  • When driving up a normal 30ft on-ramp at 45 mph, in 3nd gear on my automatic transmission(Over drive hasn't kicked it), at around 3,000 rpm I'm putting out a TON of black smoke, when I have the pedal about midway to the floor.
That way, is it your foot, or is your injection pump over fueling?

Also, do you have an exhaust gas temperature gauge? If so, what temperatures are you seeing
Click to expand...
 
I drive this thing really easily, and pretty much never push the pedal too far. I would say that it puts out smoke and jusI drive this thing really easily, and pretty much never push the pedal too far. I would say that it puts out smoke in every gear at any RPM on any amount of incline. And I am not exaggerating. I don’t have an exhaust temp gauge, and it is an automatic.
 
How does the van perform otherwise? Are startups particularly smokey/rough for an extended time (white/black)? Does the engine have a lot of vibration to it? Is it particularly sluggish off the line?
I know it's hard to tell if you haven't owned one before that was operating right, but is anything approaching alarming levels?

Black smoke is incomplete combustion due to a poor air fuel mix. For it to be as bad as you describe, my first guess would be that someone "tuned" the injection pump but did a very bad job of it (I know mine was tuned at some point in its' previous life).

Other things to possibly look at:
IP timing- check alignment marks/reset
Air filter- clean/replace
Injectors; bad spray pattern "flooding" the cylinder (would make starts very smokey)- clean/replace
Inlet manifold carbon built up badly (EGR/turbo/blowby)- pull & clean/EGR delete/install oil separator/check turbo bearings & seals
 
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Chiming in with similar problems. I have an auto 94 l400 2.8 4m40. Brought it stateside in November. It starts fine, no smoke there, but I get a lot of black smoke on quick accelerations, typically when passing 2k rpms. It will be a little smoky on cold starts, but not too bad. It does seem to get better after it warms up, but smoke on acceleration still persists.

When I first got it, I replaced fuel, oil, air filter, did a diesel purge, egr delete. Still was getting black smoke. I took a look at the turbo and its got some play in the shaft and some oil, so thats my target fix. I installed a boost gauge and I am getting 5 psi max.

Question for you veterans. Do you think I need a turbo rebuild/replace? Which do you prefer and any recommended parts suppliers to look into?

I haven't tinkered with the van since February. Started a kitchen remodel and didn't want to juggle two projects at once. Time to get the van running right.
 
Coryolson said:
Do you think I need a turbo rebuild/replace?
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If the play is lateral and minimal, it's probably OK. If it is axial (fore/aft) then that is a sure sign the turbo is going/gone. 5psi is quite low IMO.
The oil at the turbo is probably blow by from the engine, but it could be the turbo itself (bad). But oil causes blue/grey smoke, not black.
Some small amount of black smoke on hard acceleration isn't a bad thing.
 
sk66 said:
How does the van perform otherwise? Are startups particularly smokey/rough for an extended time (white/black)? Does the engine have a lot of vibration to it? Is it particularly sluggish off the line?
I know it's hard to tell if you haven't owned one before that was operating right, but is anything approaching alarming levels?

Black smoke is incomplete combustion due to a poor air fuel mix. For it to be as bad as you describe, my first guess would be that someone "tuned" the injection pump but did a very bad job of it (I know mine was tuned at some point in its' previous life).

Other things to possibly look at:
IP timing- check alignment marks/reset
Air filter- clean/replace
Injectors; bad spray pattern "flooding" the cylinder (would make starts very smokey)- clean/replace
Inlet manifold carbon built up badly (EGR/turbo/blowby)- pull & clean/EGR delete/install oil separator/check turbo bearings & seals
Click to expand...

start ups are pretty smooth, but there is engine vibration. It doesn’t feel particularly sluggish, though my previous vehicle was an 86’ Toyota van which makes the delica seem like aFerrari by comparison.
As far as other issues go, I haven’t had any other noticeable issues.
 
My first suspicion would be a lack of boost. From underneath, check that the turbo wastegate lever is still attached to the wastegate actuator rod. If the lever is free to flap about you won't be making any boost. Check that the lever can move: pull down on the actuator rod (it's under tension and is hard to pull) and the lever should open, and then snap shut under spring pressure. If it shuts slowly, or doesn't make solid contact when it's closed, the wastegate might be stuck open.

More generally, heavy smoke under load is a low air/fuel ratio: not enough air or too much fuel.

Not enough air: I would install a boost gauge, even if only temporarily. You should be getting around 10psi. If you're not, and the wastegate is working fine (as above) check the overboost relief valve for signs of leakage- if it's excessively oily, it might be weak and opening when it shouldn't. The relief valve tends to make a loud whooshing noise when it opens, but if it's always been like that you might think it's normal.

Too much fuel:
-Has the injection pump been messed with? Check the full load screw on the back (pictured under step 10 in this post). It should have a metal anti-tamper cover over it, if it looks like it does in the photo then it's probably been adjusted.
-Check the boost compensator cover for signs that it's been removed (step 6/7). Wrench marks on the bolts, alignment marks on the cover...
 
Growlerbearnz said:
My first suspicion would be a lack of boost. From underneath, check that the turbo wastegate lever is still attached to the wastegate actuator rod. If the lever is free to flap about you won't be making any boost. Check that the lever can move: pull down on the actuator rod (it's under tension and is hard to pull) and the lever should open, and then snap shut under spring pressure. If it shuts slowly, or doesn't make solid contact when it's closed, the wastegate might be stuck open.

More generally, heavy smoke under load is a low air/fuel ratio: not enough air or too much fuel.

Not enough air: I would install a boost gauge, even if only temporarily. You should be getting around 10psi. If you're not, and the wastegate is working fine (as above) check the overboost relief valve for signs of leakage- if it's excessively oily, it might be weak and opening when it shouldn't. The relief valve tends to make a loud whooshing noise when it opens, but if it's always been like that you might think it's normal.

Too much fuel:
-Has the injection pump been messed with? Check the full load screw on the back (pictured under step 10 in this post). It should have a metal anti-tamper cover over it, if it looks like it does in the photo then it's probably been adjusted.
-Check the boost compensator cover for signs that it's been removed (step 6/7). Wrench marks on the bolts, alignment marks on the cover...
Click to expand...
Thanks Growlerbearnz and Sk66. I'll look into the wastegate actuator rod first. I would be pretty stoked if that solves it.
 
JohnVanner said:
start ups are pretty smooth, but there is engine vibration. It doesn’t feel particularly sluggish, though my previous vehicle was an 86’ Toyota van which makes the delica seem like aFerrari by comparison.
As far as other issues go, I haven’t had any other noticeable issues.
Click to expand...
If it doesn't start poorly or seem particularly sluggish I think you can probably ignore most of the more basic things... i.e. turbo/boost/injectors.

I think a clogged/carboned inlet manifold is still possible, but it would have to be pretty bad. E.g. inlet manifold not letting additional air through while the IP is simultaneously increasing the fueling ratio w/ throttle/boost. In fact, I think a clogged inlet manifold could cause the IP to see a boost pressure higher than it should for a given RPM, which would exacerbate the AFR mismatch even farther.

I'm still with previous "performance tuning" as being most likely... advancing the timing for performance/acceleration can cause increased smoke. And the tension adjustment screw in the boost compensator Grant mentioned is also called "the smoke adjustment screw."
 
sk66 said:
I disregarded a lack boost as a probable cause for smoke because fueling increases as boost pressure increases... shouldn't the AFR remain pretty consistent w/w-o boost?
Click to expand...
You'd think so, but there seems to be a bit of over-fuelling built into the base tuning. Without boost my engine was quite smoky. Also very, very slow, so on further thought that might not be the problem here. But checking the wastegate is quick and easy. (I'd still rather have a boost gauge).
 
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