Once upon a time there
was an emergency room nurse who worked the midnight
shift. Every now and
then, on her way home, her car would die. It always
happened after she had
traveled far enough from the hospital to be truly
stranded. And since it
happened late at night, it always left her terrified for
her life. But,
fortunately the car never left her stranded. It always restarted
right away and got her
home. It would happen only once.
Maybe it was the fact
that she worked in the emergency ward. She had terrible
visions of being mugged
by Jack the Ripper. Maybe it was her job that made her
think this way, after
seeing so many gunshot wounds and huge knives sticking out
of bleeding bodies. She
feared someone was making her car die, since it always
happened just about the
same distance from the hospital.
To make matters worse,
she had taken the car to just about every shop in town
and no one could find her
problem. Various mechanics had already replaced the
computer twice and every
sensor at least once _ some several times. A couple of
new distributor caps,
rotors, ignition wires, ignition modules, fuel pumps, and
a multitude of fuel
filters had been installed. She had already sunk a bundle
into the car in an effort
to fix the problem.
Still, the problem
remained. The car would just die and drift to the side of the
road. Not every night,
just sometimes. And after she sat for a few moments in a
panic with her heart
racing, the car would always restart, as if it was haunted.
Funny, it seemed as if
nobody wanted to believe her. All the mechanics who
worked on her car treated
her like she was crazy. They would keep the car for a
few days, even a week and
never have it die for them. Maybe she was crazy, or at
least she began to doubt
her own sanity. Then the car would do it again and she
would once more have the
fright of her life.
One of the other nurses
at the hospital overheard her talking about her car's
dilemma and suggested a
mechanic who specialized in hard-to-find drivability
problems. In desperation,
she called up and made an appointment to have Vic look
at her car. When she told
her story, Vic responded with assurance that he would
be able to fix the car _
"once and for all." She wanted to believe him, but had
already been ripped-off
by so many shops before.
But then he did something
different. He told her that he would be connecting a
device to her car that
would be capable of recording the problem. She was to
continue to drive the car
and when it stalled, push a button on what Vic called
his "flight recorder." He
then connected a funny-looking box up to her car and
gave her detailed
instructions on what she was supposed to do when it happened.
He told her to go about
her business as usual, but at the moment it happened,
she was to quickly press
the big, red button on the recorder and keep her foot
steady on the gas pedal.
He said that if she pumped the gas pedal, or brake, it
would make it harder to
find out what went wrong. "Giving it gas makes a whole
bunch of other things
change and it makes it harder to spot the real problem."
She said she would do her
best.
On her way home the very
next night it happened again. Just as instructed, she
pressed the big, red
button on Vic's flight recorder. As always, she freaked out
and steered the dying car
to the roadside edge. As always, it restarted with
just a twist of the key.
She could hardly wait until the next day so Vic could
find the problem and fix
her car.
Much to her surprise, Vic
wasn't even interested in her story. He told her to go
to the waiting room and
let him examine what had been captured on his flight
recorder. A few minutes
later he came into the waiting room and said, "The
others may not believe
you, but I do. I saw your car die on the flight recorder.
It definitely died... and
you were going about 45 mph when it happened."
She felt her face flush
as she breathed a big sigh of relief. For the first
time, she felt taken care
of. Vic told her to take the car home and make arrangements to drop it off for
further, more thorough examination. She offered
to call a friend and
leave it. Vic said OK.
Carefully, Vic poured
over the data captured from her dying car. In much the
same way that an airplane
flight recorder remembers what happened before the
plane crashes, his
recorder remembered what was happening when her car died. It
was all there; he just
had to make some sense of it.
Because there is so much
different information to examine, Vic copied the
readings from the
recorder onto a sheet of paper. He especially wanted to see
what happened when she
pushed the button. Sure enough, at the second before she
pressed the button, the
engine dropped 400 rpm. In the next moment it went back
up to 2400 rpm and a
couple of seconds later it dropped to 500 rpm. Then in the
next second it would come
back to life and then die again. This time it would
not recover.
Frame by frame he
examined the data. One thing seemed obvious: it was somehow
related to the fuel
system. Each time it faltered, the mixture went totally
lean. Each time it
recovered, the mixture went rich. It was just like it was
running out of gas. Or
was it? He immediately thought of the fuel pump. But
could a failing pump turn
the fuel off in one second and back on in the next?
No. If the pump were to
die it would take more than a second for the engine to
run out of fuel. It would
be much more gradual.
Fuel filter? No, he
reasoned. Fuel filters don't come and go. They just plug up
and stay that way. Fuel
filters never unplug. Ditto for a catalytic converter.
And he knew the ignition
module wasn't at fault because he watched the engine
lose rpm's over a time
span of a couple of minutes. If the module were to fail,
the rpm's would just drop
to zero _ all at once.
What about the injector?
Could it be sticking? Maybe it sticks shut every now
and then. Maybe the
injector has a weak spring and sometimes just decides not to
open and stays shut. But
why only late at night? Why does it work fine once it
stalls? Why couldn't
anyone else witness it? He thought about the other repair
orders, each full of
attempted repairs and each with a hefty price tag.
No one had replaced the
injector on this 4-cylinder throttle-body fuel injected
car. Still, the fact that
it only happened late at night nagged at him. After
studying the recorded
data, Vic only had an educated hunch. Armed with his best
guesses, he was ready to
look at her car and begin checking out his theories.
The first thing he wanted
to examine was the injector.
Remember, at this point
he had not even lifted the hood of the car. Now he did
so, and removed the air
filter to get a better view of the injector. "So far, so
good," he thought as he
reached for the injector harness plug. He was about to
connect his injector
tester to the single throttle body injector when he saw it.
It was grossly green,
slimy and looked very nasty. The injector connector was
being eaten up by what
looked like green fungus!
"That's why it only
happened late at night! The humidity in the air was enough
to make this connection
have too much resistance. And when the car died and sat
for a few moments, the
heat from the engine would dry it out, giving it a good
connection for the rest
of the way home," Vic told her.
He carefully cleaned and
tightened the injector connector and fixed the nurse's
car without replacing a
single part. And the nurse lived happily ever after!
