Engine/Transmission (1994 - 1998) Smoke on Long Downhills

[Todd G]

My truck will smoke big-time on long downhills. This usually happens at the higher altitudes. My exhaust temps get really low at around 200 degrees and the smoke show begins. I know I am overfueled a wee bit I now have my AFC wheel spun in about 1/3 of the way and still get smoke. I also get lots of smoke when I start up at high altitude (8000ft). For the first mile or so it runs very rough and kills every insect in the area. I assume my timing could be the culprit. Any other suggestions?

 

[Desperado]

What color is the smoke? If it is blue/white it could be that it is just running a little to cool. Same thing has happened to me, then when it gets warmed up it dosen't smoke.

 

[Todd G]

Smoke is blue/white. It doesn't matter how warm the engine is. Are my 370's pushing too much fuel at off-throttle? I get people passing me pointing to m exhaust.

 

[moparguy]

Todd, my truck does exactly the same when out West. It's just the effect of all that air flowing through the combustion chamber and not enough heat to burn the fuel still being injected. The result is the observed white fuel smoke.



I've always thought that advancing the timing would help, haven't tried that yet. If I ever do, I'll report the results.



RJR

 

[Hogan]

This is the reason I tell people my truck is 'Skeeter Repellant'.



I live at 5100+ft and there are 3 times when my truck will clear skeeters within a 5-mile radius:



1) First thing in the morning at 1200+rpm with little or no load, at idle if it's below 30F. Get on it and the smoke goes black instead.



2) Downhill with slight throttle, at about 1500rpm and above. No throttle and more throttle makes it go away



3) In parking lots if the engine is still running cool and I drive around in 1st or 2nd gear at 1500+ rpm, not enough load to make boost.



With the mods I've done, it's a simple case of too much fuel and not enough heat/oxygen. When I first noticed it after moving from sea level in California it had me worried, now where I live it's how I can tell who's modified their Dodge/Cummins. No smog tests up here, either, so a lot of the local dump truck drivers have done mods to their trucks as well, only they're more pronounced in the morning and sitting around idling.