So today I was driving down the road. I lugged in 3rd coming around a corner when I should have shifted to 2nd, the truck didn't seem to mind, but it pillowed out black smoke when I did that and felt like it picked up faster than normal, like it had more power all of the sudden. I shifted into 4th and kept going. Once I got down off the beaten path, I tried to make it do it again, but it wouldn't smoke like that, just a normal light haze. What gives?

Stock '97 Dually 5-spd, Only mods are BHAF, Fuel plate full forward and starwheel about 3/4 forward, stock exhaust and everything.

 

Bueller? Bueller?

 

two much preboost fuel before the transmission down shifted. back off on the star wheel to correct it.

 

How come I can't duplicate it? I tried again last night but it just did the lighter dense smoke like normal and not the thick soot. The way I remember, I released the clutch in 3rd, it barely lugged, then the truck picked up faster than normal and laid down a trail of dark black smoke. I don't get it.

 

Sounds like the pump over corrected for the low boost condition and maxed out the rack travel....my old 95 would do this on occasion, and I never could figure out the trick to do it on purpose. So I just added big DV's and injectors and I could smoke at will!

BTW, that is not a technical explanation at all...I'm drawing a blank on how it actually happens
Chris

 

I have a JD tractor that was doing much the same when I hit a bump hard.
Ended up being the seat switch that killed the engine when you weren't there.
I just bypassed it, PITA anyway.
Anyway the way the seat safety worked was to cut power to the shutdown solenoid. Makes me wonder if you might have a bad connection to the solenoid or key switch.

Hate these intermittent problems, sometimes you have to wait for it to fail completely to figure out where it's coming from.

 

Ain't that the truth Bill!

Chris

 

It's only done it once, no bumps, no incline, nothing.

 

if you want it again but better slide your afc housing full foward and when you shift you want to earlier than normal so the turbo isnt spooling as fast and basicly floor it, it should smoke

 

you could have simply let the clutch go to fast