[Vwdiesel] smoke related to driving style

[Randy Tyler]

I subscribe to the fouled injector theory. 
 
Improper spray pattern is causing unburnt fuel.  If it were simply accumulated soot in the exhaust system, you would get caking of the carbon or coking in combination with the moisture in the exhaust. Applying power with the esuing rise in exhaust temperatures will start the carbon burning.  My truck driving brother-in-law has seen muffler fires in the big rigs (jumbo lorries)  especially at the top of long grades.  Look at some of these trucks and the hot spots on the exhausts.
 
IMHO I would back off the power and keep moving to get some air cooling around the outside of the exhaust system and look for a safe place to pull off.  I would keep the engine running.  I would check the cargo area of the vehicle for hot spots.  What about those heat shields between the fuel tank and the exhaust system that were removed earlier because they were in the way?
 
IMHO I think the black smoke is maintenance related not driving style.
 
Randy
Val Christian <val at mongobird.com> wrote:
> 
> Could it just simply be gentle driving allows accumulation of soot in the
> exhaust. Extra energy in flooring it loosens it off again. After all the

Don't think so. It happened on a tractor I used, with only the 
exhaust manifold on. Not much to collect soot in, compared with
the visible carbon emissions.

> turbine manages to find the extra energy and turn it into mechanical
> energy. So why can't the soot particles see this energy too.?
> One of my paranoia's is that the annual opacity test involves flooring it
> by the inspector. "Readings spoilt by loose soot?"

I suggest driving it hard just before the test. 

My theory is that the hard drivin' stomps off the gunk
on the injectors. Doesn't happen with brandnew injectors
until they have 5 or 10K on them. Doesn't happen as much
with newer injectors with conditioner in the fuel.

Theory only.

Val


> MTM
> ----- Original Message -----
> From: Val Christian 
> To: Sandy Cameron ; 
> Sent: Monday, November 07, 2005 12:44 AM
> Subject: Re: [Vwdiesel] smoke related to driving style
> 
> 
> > The exact same symptoms occur on my car. The mileage reported is about
> > the same as well. I have a 91 NA.
> >
> > No turbine wheels. We need a new theory.
> >
> > Strawman theory. Light foot allows carbon and longer chain molecules
> > build on the pintle and other portions of the injector, and are knocked
> > free with high fuel flows.
> >
> > Observations: Driving hard, keeps smoke clean all the time. Rara to the
> > lead foot. Also, keytone and tolulene additives "injector cleaners"
> > and "fuel conditioners" seem to reduce the intermittent lead foot
> > smoke production. "Stomp smoke."
> >
> > Val
> >
> > >
> > > At 05:40 PM 11/5/05 -0500, you wrote:>
> > > >Is it a carbon build up issue? It only seems to do it when I drive it
> easy
> > > >and then push it hard.
> > >
> > > My TD does that. Reason says that carbon sticks to the turbo wheel with
> easy
> > > driving, and comes loose on high boost / high RPM
> > >
> > > Effective way to disuade tailgaters. I always seem to have a supply in
> store
> > > when needed.
> > >
> > > Sandy
> > >
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> >
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> 
> 
> 
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