“Dr. Gizmo”
By Phil Arendt
Loss
Of Magnetic Field
Question
1
The
check engine light turned on in my 2007 Volkswagen Jetta Wolfsburg Edition. It has a 2.5 engine and 107,000 miles. The engine was running normally but I took it
to a reliable shop that has been servicing it for many years. They did several tests. They checked for compression and
misfires. They found one cylinder was
misfiring more often than others. They
replaced the fuel injector, spark plug and ignition coil but the mechanic says
this cylinder and others still misfire.
He does not know what causes the trouble. He says I should drive it until it gets
worse. I took the vehicle as is.
I
feel the car is running normally but the light is on. I’ve owned it since it was new and it seems
fine. I do need to get this repaired
before a state emission test but for now I’m going to drive it. Could this be caused by a computer problem? H.K., email
Answer
1
Maybe,
but more probing is needed. It appears
your technician found random misfire codes with one cylinder misfiring more
often than others. He attempted to
resolve the issue with the parts he installed but the misfire condition
continued.
At
this point it is time for him to think out of the box. Maybe this will help. A search of professional web sites found a
rare case with similar symptoms. In this
case a technician found a magnetic dead zone on the crankshaft ring. The crankshaft ring is monitored by a
sensor. The sensor sends a signal to the
engine computer. The engine computer
uses the signal to fire the spark plugs.
If the magnetic field on a portion of the ring is lost, the spark plugs
will not fire at the proper time. Perhaps
your technician might take this into consideration the next time your wheels roll
into his service bay. If he finds this
is the cause of the trouble replacing the ring will cure the issue.
New
Pump No Cure
Question
2
The
power steering failed in my 2011 Chevrolet Silverado 3500 HD. It has 142,000 miles. I went to a shop where they replaced the
pump. This reduced steering effort but
now fluid leaks from the cap on the reservoir and the steering is not as easy
as it used to be. My shop replaced the
cap but this has not fixed the trouble.
They said they contacted a tech line and were told to check for blockage
in the steering gear. They replaced the
gear but the trouble continues.
Do
you have any suggestions? D.L., email
Answer
2
It’s
possible the newly installed pump is defective.
It’s also possible lines connected to the pump were not properly
installed. Perhaps the hydro-boost unit
in the system has a defective valve.
Since fluid is leaking from the cap, suspicion points toward an issue
with the pump or installation of the hoses connected to it. Ask your shop manager to consider another
look at the installation.
Blown
Tire Impairs Engine Starts
Question 3
The
right rear tire blew out on my 2014 Dodge Charger R/T. I limped to the roadside and shut off the
engine. As waited for road service I
attempted to start the engine but it did not respond at all. I had it towed to a shop where the car would
not start for them. They replaced all
four tires and performed several tests to determine why it would not
start.
They
told me to come to the shop with all my key fobs because they thought there was
an issue with the one I gave them. The
car does not respond to either key fob.
The door locks and other functions do not work. When the start button is pressed to start,
the car does nothing. They checked the
car battery and batteries in the fobs.
The batteries are fine. Now they
suggest that I have the car towed to a dealership for further diagnostic
work. Before I do that do you have any
suggestions? R.B., email
Answer
3
It’s
time to trade it in for a 2018 Dodge Charger Hellcat. All kidding aside it appears excessive tire spin
wear might be an issue and possibly the cause of this condition. If so trading your wheels for a 707
horsepower Hellcat will cause more trouble.
Since the no-start problem began with a blow-out at the right rear tire
it may behoove a technician to look for damage beyond the wheel house
liner. It’s possible tire debris damaged
wiring or components hidden behind the liner.
If there is damage to conductors or components this causes modules to go
bonkers. This could cause the all the
trouble. Repairing a broken or shorted
wire might be the cure you seek.
Many
Appreciated Thanks
Question
4
Good
morning. As always you have excellent
articles. Recently, I read a question
from L.M. about an S10 and another question about a 1997 Dodge that stall after
10 minutes. I'm going with a failed crankshaft
sensor. Will I see the answers down the
line? D.D., email
Answer
4
The
answers accompany the questions. It
indeed is possible that a failed crankshaft sensor is the cause of the stalling
engines in both vehicles. Sometimes we
receive an update from a reader. Often we
do receive a thank you that states the diagnosis and repair has cured an
issue. When we do receive a thank you,
it is much appreciated and is the main reason for writing this column.
Ticking
Sound Ends With Expensive Repair
Question
5
Dear
Dr. Gizmo, keep up the great work. I’m
writing in regard to H.M.'s letter in today’s paper about a tapping noise in
his 5.3-liter engine. I too suddenly
developed a loud banging tappet noise that proved to be a $3,500 serious
problem. When the problem occurred, I
was able to limp into my Chevrolet dealership. This engine has roller tappets. Groups of four tappets are incased in a hard
plastic-like housing, which guides their up and down movement while riding on
the camshaft, holding them at the correct angle so that the roller stays parallel
to the cam lobes. Unfortunately, this housing wears out allowing one or more
tappets to start to rotate eventually to the point where the roller no longer
rolls but starts to slide 90 degrees to the camshaft causing damage to the lifters,
valves and camshaft. I understand that
this is not an uncommon problem with this engine. My 2008 Avalanche was seven years old at the
time of this problem with 63,000 miles on it.
I
hope this is not the problem with H.M.'s 2008 Silverado. Do you?
P.G., email
Answer
5
H.M.
was concerned about a ticking sound in his truck. It is possible the 5.3-liter engine is
suffering from the same condition. Let’s
hope not. Ticking sounds are a symptom
of several afflictions. A simple problem
such as an excessively worn serpentine belt might exhibit ticking sounds.
Add-On
Damages Engine Computer
Question
6
I
have 2004 Chevrolet Silverado 2500 HD with a 6.6-liter engine that I purchased
about a year ago. It has 115,000 miles
and is in like new condition. Recently,
I took it for an emissions test. It
failed.
I
went to a shop that specializes in GM diesel repairs. A technician tested the computer and found
that his test equipment does not communicate with the truck. It’s the same problem the emission center was
having. My mechanic proceeded to
reprogram the computer but had the same problem. After some examination he found a tuner
device was installed. He removed it but
the computer still did not respond to reprogramming. Now he says the computer must have a virus or
was corrupted by the tuner device. He
says he needs to replace it. Does this
sound right to you? R.S., email
Answer
6
Congratulations
on your recent purchase. Once this issue
is resolved it might roll along for another 200,000 miles or more before the
engine needs major repair.
First,
some readers might not know what a tuner is.
It’s an aftermarket electronic device that a person adds that alters
factory computer programming. It is intended
to enhance engine performance such as fuel economy and horsepower.
As
for the trouble, the tuner might have permanently altered the engine control
module. If so, the fix is to remove the
tuner and replace the failed module with an original equipment part.
Thank
you for all the great questions. Dr.
Gizmo can’t wait to answer more.
Phil Arendt is a columnist,
consultant and A.S.E.-Certified Master Technician. Readers may send questions to Dr. Gizmo at
his e-mail address drgizmo@drgizmo.ws.
More information is available at http://drgizmo89.blogspot.com 01/22/2018 ® DR. GIZMO © 1989 – Present
