Occasional heavy black smoke!!!!!

[Tyler yakubchuk]

i have a 96 6.5 turbo diesel half ton that seems to on occasion loose a bit of power and blow a lot of black smoke. The truck has 4 inch straight pipe and I can hear the turbo spooling even when the smoke happens. There seems to be a little loss of power when it blows smoke but it only last about ten seconds then goes away and seems to be intermittent so it doesn't do it all the time. Could this be an egr problem? Also it seems to do it more often when it's hot outside.

 

[ak diesel driver]

I'd be leaning towards an EGR issue

 

[Will L.]

My first thought was egr, other than that, is there a heavier knock when it happens-injector starting to stream?

 

[Tyler yakubchuk]

No knocking just a slight loss of power and smoke like a freight train.

 

[Husker6.5]

Is it doing this under moderate to hard acceleration? Light acceleration? Steady-state cruising? How many miles on the vehicle and what (if anything) has been replaced on it (ie: injectors, IP, vacuum pump, etc?

 

[Tyler yakubchuk]

Usually happens when starting from a dead stop I would say under moderate acceleration I guess. The truck has about 170miles and has had a new vacuum pump, pmd, and lift pump all within the last 10 thousand miles I have never done anything to the ip but I am the second opener of the truck so I don't know the total history.

 

[Husker6.5]

If you have a hand-held vacuum pump, (like a Mite-vac for brake fluid changes) I would check the wastegate actuator and make sure that it holds vacuum and operates the wastegate actuator arm smoothly. At idle with the hose disconnected, check for good vacuum at the hose end at the actuator. The GM-X series of turbos are not the fastest spooling, and even if you roll into the throttle from a stop at idle instead of mashing the go-pedal down, they will smoke for several seconds before they turbo spools up and they get on boost. Note that the average life expectancy of injectors is ~ 100K miles (160K Km) and of an IP ~150K miles (240K Km) and either starting to wear out can cause intermittent over fueling. Do you notice a light surging of maybe 30-50 rpm when steady speed cruising (feel seat of the pants, not necessarily can see it on the tachometer)?

 

[JMJNet]

Did you replace the vacuum lines/hoses when you replaced the Vac Pump?
Those plastic lines are usually brittle with age.

Also, never assumed that new parts as good parts.

 

[Nosferatu49534]

X2 on vac lines. Mine all cracked. Replaced them with good rubber vac lines and a new vac solenoid and boom, no more black smoke and peppy as could be for 240,000 plus. With my truck running I just ran the line from the vac pump straight to the diaphragm on the waste gate to make sure that was operating. After that I went back through the solenoid and determined that was my original cause. I think it cost me maby $30 +/- a few for the hose and solenoid.