smoke - why?

[ilovetrains]

I have noticed lot's (I mean a great black fog) of smoke out of my truck at times, and nothing others. When I notice it under probably 3/4 acceleration load, empty or pulling something. I saw a post about if you were lugggin it around it would build smoke and then blow it out. Mine seems to come and go, but never in relation to type of driving etc. Thought fuel but does not last a full tank. Does it hot, not so much cold.



Any ideas?

 

[mhlbr]

are you running stock or have fuel boxes on?? If its stock, thats weird on an 05. I can not get mine to smoke when lugging or towing. If it does it when its hot, makes sense, hotter the air = less oxygen = les combustion. When it smokes like that, does it run rough or different??

 

[DavidBurt]

My 05 2500 six speed will make alot of smoke under hard acceleration empty or loaded. When it hits about 2100 RPM with more than half throttle it will make a heck of a cloud, and really take off. I only let it get over 2000 RPM when trying to accelerate fast, and then shift it at 2700 or so.

Dave

I think it does this because the boost is catching up with the fuel. When you get into it it takes a little bit for the turbo to spool up to match the fuel.

 

[ilovetrains]

stock, for now. Smoke seems excessive, but David experience seems similar to mine. What irritates me is I don't seem to be able to control it. Some times, no matter what I do it will smoke, but other times, when I would dump some black smoke on somone, it won't do it.

 

[DavidBurt]

Mine does it every time I stand on her.

Dave

 

[Tomeygun]

stock, for now. Smoke seems excessive, but David experience seems similar to mine. What irritates me is I don't seem to be able to control it. Some times, no matter what I do it will smoke, but other times, when I would dump some black smoke on somone, it won't do it.

That sounds wierd, Stock trucks are made to only fuel once boost is present. That makes me think it could be a mechanical problem, Like a funky injector. Maybe putting fuel in at the wrong amount



When you say "great black fog" - Do you mean about 3-5 feet long, and you can see through it and then it quickly is gone?

 

[67guzzler]

I've found a pattern. If I've been keeping the rpm's below 2000 and accelerating slowly for a couple days and then I punch it I'll get a major plume. If I punch it 3 times in 5 minute period, it's almost clear. If I drive more aggressively and shift above 2k rpm's, when I punch it, it will not put out the plume that it would if I had been driving gently prior. I think it's soot buildup in the exhaust system that's getting blown out.

 

[Tomeygun]

I've found a pattern. If I've been keeping the rpm's below 2000 and accelerating slowly for a couple days and then I punch it I'll get a major plume. If I punch it 3 times in 5 minute period, it's almost clear. If I drive more aggressively and shift above 2k rpm's, when I punch it, it will not put out the plume that it would if I had been driving gently prior. I think it's soot buildup in the exhaust system that's getting blown out.

Maybe because of the Cat converter?



thats the only thing I can thing of that would hold soot that you could blow out with enough flow

 

[DavidBurt]

JGann, Mine may only occur after a while of babying it too, because 99% of the time I shift at 1800 or 1900 Rpm. But when I do get into it it will leave a cloud but like Tommeygun says you can see through it.

Dave

 

[67guzzler]

Good call, tomeygun. Must be the CAT. My 2004. 5 did this too. Once I found the pattern I didn't worry.



This is a little OT but I also noticed that now that I'm running bio there is just about no smoke -- even on cold startup. There are some 3rd gen relevant threads over in the alternate fuel section if you'all are interested.

 

[DavidBurt]

Boy that makes me a little nervous if that much builds up in the cat that fast.

Tomeygun isn't the burning of fuel what creates the boost? Or is it that the truck will only fuel so much at a certain amount of boost?

 

[nps]

My 01. 5 HO has similar smoke behavior also - but no cat. I've also got a straight through Flowmaster muffler.

 

[rbattelle]

Tomeygun isn't the burning of fuel what creates the boost? Or is it that the truck will only fuel so much at a certain amount of boost?

I believe both of these statements are true. Burning fuel creates energy in the exhaust stream to drive the turbine. But the engine fuels in proportion to boost (among other things), so the system is sort of self-regulating. At a given boost the ECM is limited to a specific maximum fuel quantity.



If you could run WOT at 5 lb boost with no proportional fuel/boost limiter you'd make a smoke cloud the size of Nevada.



-Ryan

 

[ilovetrains]

JGan - I thought that was my pattern too, but during a recent tow I smoked for about 200 miles. Should have cleared in that time.



I am talking about thick black smoke as long as I keep my foot in it. Runs fine, in fact when it smokes it usually is pulling so hard I get out of it quick, but the smoke is thick. People will back off behind me for fear it is about to blow. Now keep in mind this is like a once a week (which for me is 1K miles) occurence, but once it starts it will keep it up for a while.

 

[67guzzler]

JGan - I thought that was my pattern too, but during a recent tow I smoked for about 200 miles. Should have cleared in that time.



I am talking about thick black smoke as long as I keep my foot in it. Runs fine, in fact when it smokes it usually is pulling so hard I get out of it quick, but the smoke is thick. People will back off behind me for fear it is about to blow. Now keep in mind this is like a once a week (which for me is 1K miles) occurence, but once it starts it will keep it up for a while.

Does it ever clear & stop doing it if you keep mashing on the accelerator?

 

[TPappas]

My stock 05 smokes pretty good under hard driving if all I have recently been doing is city driving, red light to red light. If I drive on the freeway for any length of time the smoke goes away till I drive short distances in the city again.



But it does smoke a lot sometimes! Very thick black smoke too! I like it.

 

[TSpecht]

I've found the same, if I baby it for a good part of a tank, and then suddenly lay into the throttle hard, it produces *smoke*. Any good acceleration run I can see a little haze, but this smoke is black as coal and thick, which stays in the air about long enough to hit a vehicle about 100' back as it's following me. I like the feeling of looking in the rearview and seeing a column of smoke pouring out (until I realize that's $$$ pouring out of my pocket come time to fuel up)...

 

[SRadke]

Is it short of power while it's smoking or does it feel normal?



I had an exhaust brake stick on once, that made some smoke



-Scott

 

[TSpecht]

In my case, it's definitely not down on power when it's rolling the smoke. I think either the cat or restrictive stock muffler is trapping soot from normal driving and a hard run just blows it all out.

 

[MMeier]

Change your air and fuel filters lately?