Repeatedly Running On A Low Tank?

"'95 EFI.", so no.

 

Oiled foam filters and oiled gauze filters are not equivalent. You can't
apply the experience with one to another.
......

Police cars spend a lot of time idling....exactly the sort of condition that
should trigger more frequent oil changes. The normal maintenance schedule
assumes a direct relationship between the number of miles traveled and
number of engine revolutions. Any activity that involves a lot of idling
drastically changes this relationship.

Big trucks do things like that all the time. My last GM car included an oil
life monitor. Initially I did not trust it, but I once went almost 7500
miles before I changed the oil (the light never came on). I sent the oil off
for analysis and the analysis that came back indicated the oil was still in
good condition and certainly could have gone another 3000 miles. Given
today's oils and engines, I think 3000 miles is a ridiculously conservative
oil change interval for most drivers. Oil change places keep promoting
excessive oil changes by misstating the severe service requirements
published by most manufacturers. I think Toyota did the right thing when
they eliminated the normal / severe service schedules and just went to a 5K
across the board schedule. My Nissan has a 7.5K normal, 5K severe service
schedule,but I usually just stick with the 5K schedule (simpler). My Ford
has a 5K/3K schedule, but I also stick to the 5K schedule for it. I am not
doing anything that would remotely qualify as severe service. My SO and
Sister but have RAV4's. These vehicles have a 5K maintenance indicator
light, which is very convenient. It is not as nice as the GM oil change
indicator, but certainly better than depending on memory.

People that blindly do 3K oil changes are wasting a lot of money....does
that make them a fool?

Ed

 

NO WAY!!!! I lived with those for years on farm tractors. It is not even
close. Modern paper filters are far better.

Ed

 

There is only one reason why this should be true for a modern fuel injected
engine - it was so restrictive it limited your power. Otherwise it should
have no effect on fuel economy (compared to a properly serviced paper
filter). As long as you are talking about a properly serviced air filter,
the air filter restriction is no different than the throttle plate
restriction as far as the engine electronics are concerned. If the air
filter is so screwed up it could effect your fuel economy, it should also
trigger the check engine light.

When people claim unbelievable fuel economy improvements for air filters, I
usually assume it is due to poor data collection, poor maintenance of the
old filter, a change in driving habits (possibly triggered by more noise
associated with open cone filters), or just wishful thinking. Do you think
it is possible that Toyota did such a poor job of designing an intake
system, that some random aftermarket product could improve the fuel economy
by 4 mpg (more than 12%). Why would by a car from a company that would be
that incompetent? If improvements of this magnitude were obtained merely by
changing air filters, don't you think all the manufacturers would make the
switch? How happy would Ford be if they could up their CAFE average by even
a tenth of your claimed increase?

Ed

 

Only if more air is being drawn into the engine, so that the PCM has to
inject more fuel to maintain the correct Air/Fuel ratio. The only sensor
that actually measures the throttle position is the throttle position
sensor. The throttle position sensor (TPS) is a very gross indicator. It's
primary purpose is to indicated changes in driver demand. Think of it more
as an accelerator pump and dashpot than as the primary device used to
determine the amount of fuel injected. In closed loop mode, the amount of
fuel injected is primarily controlled by the MAF, RPM, temp, and O2 sensors.
In order to make sure the engine runs correctly in open loop mode, the PCM
collects data and learns offsets during closed loop mode that are used to
correct sensor data when running in open loop mode. Think of it this
ay -the difference in restriction between a dirty oiled gauze filter and a
clean paper filter is negligible. Look back at your log book - does the fuel
economy decrease measurably between cleanings of the oiled gauze filter?

Only at wide open throttle.

Ed

 

Better throttle response, or more noise? I sometimes think the two are
related. It is possible throttle response was improved but it seems
unlikely. To be honest, I am not even sure what improved throttle response
means.

Ed

 

Well, Here is some pretty good information that would tend to support
my position over yours.:

The oil-bath air-cleaner is a classic example of a two-stage' kinetic
filtering element, removing virtually all particulate contaminants
from the air at all engine speeds.

Incoming air is forced to follow a vertical descending path toward the
pool of oil then drawn upwards. Having a mass several million times
that of a molecule of air, the inertia of the dust particles makes it
impossible for them to follow the abrupt change of direction in the
air-stream, causing the particles to strike the pool of oil where they
become trapped. This works best at high rates of air-flow.

The coir filter element, which forms what is termed a 'labyrinth
filter', applies the same principle but in a different manner. The
coir element forces the air to change direction many times. The fibers
are coated with kerosene. Dust particles collide with the fibers and
are trapped by the kerosene.

The spec for cleaning the coir filter is to immerse it in kerosene,
allowing it to soak for up to half an hour. It is then sloshed
repeatedly and allowed to drain. This was done twice a year under
normal driving conditions, as often as deemed necessary under dusty
conditions.

In use, particles of dust trapped in the oil bath cause the level of
the oil to rise. Under severe conditions it may require cleaning on a
daily basis. (Moisture does the same thing. In a rainy climate it
isn't unusual for the air cleaner to accumulate a quart of water per
month.)

Under Volkswagen's original apprenticeship training program the
effectiveness of the oil-bath air-cleaner was demonstrated by removing
the sludge from a the oil-bath and coir filter, flushing it with
solvent and examining the residue. A low-power microscope was needed
to observe the smallest particles.

The same principle is used to clean the air for large stationary
engines and for air conditioning applications, in which a
recirculating water-bath may be used instead of oil, and the air may
be forced past as many as two dozen up-down baffles, removing even
microscopic particles of low density such as pollen. In some systems
the water-bath is sealed with a thin film of mineral oil. Trapped
particles fall thru the oil and are removed by the recirculation of
the water beneath the oil film. I understand special silicone-based
oils are used in modern HVAC systems but non-human applications such
as large stationary engines continue to use mineral oil. Residential
HVAC systems typically use labyrinth-type filters, designed primarily
to catch fibers rather than particles.

Paper and foam filtering elements are based on the labyrinth
principle. The effectiveness of the oil-bath air-cleaner is superior
to that of the typical paper or foam filtering element. Paper
air-filtering elements came into use when they became effective at
trapping particles of a certain size. Oil-bath filters will trap
smaller particles but there is no evidence of accelerated engine wear
for particles below a certain critical size.

Air filters for rough service (armored vehicles, farm machinery, etc)
where an oil-bath would be unsuitable, and high-volume applications
(turbines, etc) use the same physical principle of
mass-differentiation, typically drawing the air through several stages
of centrifuging during which the greater mass of the dust particles
causes them to be separated from the air-stream. Although such
air-cleaners may be powered or static, they are often called 'turbo'
air-cleaners. They are often used in conjunction with disposable
labyrinth-type filters. For Volkswagen owners running off-pavement,
the static type of 'turbo' air-cleaner used on Ford tractors has
proven most effective.

Recent air-pollution legislation enacted here in California requires
automotive paint shops to reduce their emission of vapor and
particulate material. I mention this because the most cost effective
means of doing so involves the use of high-volume, low-pressure
spray-painting systems in conjunction with a multi-baffle water-bath
air-cleaner that uses exactly the same principle as the air-cleaner on
an early Volkswagen.

-Bob Hoover -4 May 1997

 

More:
Oil Bath:
An oil bath air cleaner consists of a round base bowl containing a
pool of oil, and a round insert which is filled with fibre, mesh,
foam, or another coarse filter media. When the cleaner is assembled,
the media-containing body of the insert sits a short distance above
the surface of the oil pool. The rim of the insert overlaps the rim of
the base bowl. This arrangement forms a labyrinthine path through
which the air must travel in a series of U-turns: up through the gap
between the rims of the insert and the base bowl, down through the gap
between the outer wall of the insert and the inner wall of the base
bowl, and up through the filter media in the body of the insert. This
U-turn takes the air at high velocity across the surface of the oil
pool. Larger and heavier dust and dirt particles in the air cannot
make the turn due to their inertia, so they fall into the oil and
settle to the bottom of the base bowl. Lighter and smaller particles
are trapped by the filtration media in the insert, which is wetted by
oil droplets aspirated thereinto by normal airflow.

Oil bath air cleaners were very widely used in automotive and
small-engine applications until the widespread industry adoption of
the paper filter in the early 1960s. Such cleaners are still used in
off-road equipment where very high levels of dust are encountered, for
oil bath air cleaners can sequester a great deal of dirt relative to
their overall size, without loss of filtration efficacy or airflow.
However, the liquid oil makes cleaning and servicing such air cleaners
messy and inconvenient, they must be relatively large to avoid
excessive restriction at high airflow rates, and they tend to increase
exhaust emissions of unburned hydrocarbons due to oil aspiration when
used on spark-ignition engines.

 

Actually, the 82HP 1.5 liter in 1994 was carbureted. The 1995 93HP 1.5
liter engine was injected.

 

I worked with them for years on farm and industrial equipment.(both as
user and mechanic) Properly serviced they WERE extremely effective.I'd
say properly sized they were more effective at filtering across the
broad spectrum, if slightly more restrictive.
Combined with a "turbo" pre-cleaner to catch the flies, bumblebees and
gravel stones not much dirt of any description got through. It took an
hour to properly service one though - and it was a DIRTY job.

 

Yeah - I saw that after I posted.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

 

I drove a '65 International Travelall with the oil bath air filter from
my mid teens until the early 80's when I sold it, so I am familiar with
this type of filter.

You had me at "More:", but did you shoot your argument for its efficacy
in the foot when you said "and they tend to increase exhaust emissions
of unburned hydrocarbons due to oil aspiration when used on
sark-ignition engines", being that that oil that would thus be aspirated
would have been the medium that contains all the dirt that was caught?
I think I see the answer to my question in your explanation, but I want
to see what you will say. This is a very intersting discussion.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

 

jim beam wrote in message ...

Nuh,
We're talking duel fuel cars

When you switch over to LPG from petrol the petrol pump keeps running.
Don't know if the car computer monitors fuel pressure and that's why they
keep the fuel pump working. I was running on LPG and the petrol was pissing
out of a break in the petrol line.

 

All kinds of LPG conversions - but THAT one would never pass in
Ontario. Only one fuel source can be "live" at any one time. Shutting
off the injectors alone is NOT adequate. No EFI system I am aware of
senses fuel pressure.

Some EFI engines are difficult to dual fuel because the computer
(which controls fuel AND spark) needs to see the load on the injector
circuit to avoid throwing a code.You need the computer "happy" to
operate the spark timing.

Also, if the mixture goes off, the computer cannot correct unless you
are using a "piggyback" liquid injection system. (or a propane
"augmentation" system - which feeds the engine propane, but on the
lean side - and the gasoline injection system corrects the mixture
with gasoline.

I have not seen a commercial system that works that way, which would
be the only reason for running the fuel pump while burning LPG.

 

wow, that's got to be one of the last carburetted cars on the road! for
north america at any rate.

 

the principle of how oil baths work is not at issue [centrifugal, et
al]. what /is/ at issue is their efficacy - it varies with flow rate.
none of your cites address that issue.

as an aside, it's odd to see that a paint shop is supposed use a water
baffle for hydrocarbon vapors - many of which are not typically regarded
as water soluble are they?

 

not if it's controlled by the computer it doesn't. maybe yours was
rigged in some way, but if it was, it's hardly fair to blame pump
burnout on the pump because it's not designed to run dry and is
protected from doing so by the computer under any normal application.

that's extremely dangerous [obviously]. i don't think the people that
did your conversion knew what they were doing or that would never have
happened.

 

The oil in the filter media was constantly washed out and replaced by
clean oil from the bath. So the dirt trapped by the oil was deposited
in the oil tank. Remember that the filter media was very course,
somewhat like steel wool, so dry media would be next to useless as an
air filter.

I would tend to doubt that engine emissions would be effected to any
great amount by oil drawn into the intake manifold. Unless the tank
was over filled, I just don't think enough oil would make it out of
the filter.

Jack

 

Man, you should know I'm pretty up on my maintenance. The paper filter was
about 6 months old when I did the swap.

And no change in the MIL.

I keep a book in my cars showing oil changes, mintenance (air filters,
etc) and every time I fill up. Prior to switching the air filter over I
was getting 38-40 MPG, and after ~44/45. And I didn't let my foot up at
all! You should know *THAT* by now, too!

 

Nope. Stayed a steady 43-45 MPG.