- How do I diagnose problems with egr valves, oxygen sensors,
pcv valves, and map sensors?
- HC, CO, CO2, O2 and NOx - which exhaust gases do I need
to know about?
- What about carbon dioxide emissions and NOx emissions
- what levels are acceptable?
- What makes a vehicle run rich or lean?
- TAC, EFE, AIR, CAT, TP, MAP, ECT, KS - what if they
have problems? What can I do?
- Feedback carburetors and fuel pumps - can you help me
- What is OBDII?
- Can you explain electricity, circuits and digital signals
- I don't know how to use a lab scope for diagnosis. Can
you teach me?
- How do I get a pattern on a scope? And what does it
- Is it safe to probe the wires?
- What's the difference between primary and secondary
- Why do I need to know about relative compression?
- I am taking the California Smog Check License Exam -
what do I need to know? Can you give me practise questions
Get the answers to these questions and more
right here. Quickly discover what you need to know so you
too can perform successful auto repairs. As an automotive
teacher I explain things in plain English
so they can be easily understood. I cover electrical, computers,
emissions, engine performance, as well as how to diagnose
effectively and efficiently. Let's get you some auto repair
information now. (CA smog techs please click here.)
start with some basics...
Needs of an Engine:
Let's review the basic needs of an engine.
We will be looking at the air/fuel ratio needs of an engine,
depending on the condition when it's operating. We'll also
throw in a few comments about ignition timing needs during
1. Cold Start: When starting
cold, the sprayed fuel tends to condense on cold engine
metal, so we need a very rich air-fuel ratio to get enough
vaporized fuel to run properly. When the engine is cranking
there can't be a lot of timing advance or the burning will
complete before the piston is at the top of the stroke and
it will try to push the piston down backwards.
2. Warm Start: When starting with the engine
not as cold, or maybe warmed up, we still need a slightly
rich mixture to get started, but not as rich as a cold start.
There will still be some condensing of the fuel on engine
metal that isn't up to total operating temperature.
3. Cold Idle: We still need a richer mixture
than normal running because of the vaporization problem,
but not as rich as a cold start. We could also use more
timing advance for a smoother idle.
4. Warm Idle: Once we are warmed up, the air
fuel ratio can get closer to our middle stoichiometric ratio
for clean emissions and we will still have a reasonably
smooth running engine. Some manufacturers run at stoichiometry,
some may run the engine slightly rich to give a smoother
5. Warm Cruise: Now with higher engine speeds
and moderate engine load (higher load means the engine is
working harder-it has more air coming in) we can run right
at the ideal stoichiometric air fuel ratio for clean emissions
or even leaner to get good fuel economy. Our ignition timing
needs to be very advanced now. Since the engine is spinning
faster, we need to start the spark sooner so that the burn
is complete when it's time for the expanding gas to push
down on the piston. And leaner mixtures take longer to burn
too, since the fuel is more diluted among the oxygen.
6. Heavy Load or Sudden Acceleration: Under
these power conditions we need a slightly rich air fuel
ratio. It helps to get more power out of the engine. And
our timing can't be as advanced because the richer mixtures
burn faster, and the heavier load also burns faster. So
we don't need to start the spark as soon to have the burn
complete by the time we want the expanding gas to push down
on the piston.
7. Deceleration or Coasting: This is easy,
when decelerating we don't need any fuel at all, so we can
turn the injectors off.
Now the whole job of the computer is to analyze
the inputs to figure out what condition the engine is running
under. Then it uses the logic to figure out what fuel, timing
etc. is needed for this condition. Then with the actuators,
it outputs to the engine what it needs. A problem occurs when
some part of this process goes bad.
Since the computer doesn't have eyes and ears
like you and I, it has to have sensors to tell it what's
going on with the engine. These are the usual types: Engine
speed (and position) or RPM, Engine Load, Throttle angle or
position, Coolant temperature, Air temperature, Exhaust gas
air/fuel ratio, and a Knocking, pinging or detonation sensor.
(There may be lots of others, but these tell the major story.)
Let's look at each of these in more detail,
and what kind of information you will see on a scan tool.
Pay attention to the initials used to symbolize each of the
sensors, you will want to know that for later..."
Next I cover things like map sensors, throttle
position sensors, oxygen sensors and egr valves.
more free info...
The above info is from pages 24 and 25 of my "Smog Refresher
Course" book. Special offer here.
Electronic information available worldwide, instantly!
Emission Control Devices
Here we're going to talk about PCV, Fuel Evaporative
Systems, Thermostatic Air Cleaners, Air Injection, EGR, and
Catalytic Converters. What theory do you need to know about
how they work? How do they usually fail and cause problems?
How do we test them? And we'll have some sample test questions.
PCV:(Positive Crankcase Ventilation):
These were our first emission control devices.
(Unless you want to call a gas cap a smog device, but the
first gas caps were vented, right?)
Inside the engine crankcase, where the
oil lives and breathes we have gas vapors that got
there by sneaking past the piston rings when the piston is
compressing the air-fuel ratio or the fuel is burning up.
And the more power the engine is developing, the more of these
HC vapors get crammed into the crankcase. So, what to do?
If we have a crankcase that is totally sealed,
this gas under pressure will eventually blow out the seals.
So we have to find a way of relieving this pressure.
In the old days, when I was a child, we had
road draft tubes and open oil filler cap covers. That way
the pressure could get out, and as the car drove down the
road, suction was created at the road draft tube and it helped
pull out the gas vapors. Fresh air could come in through the
oil cap and help keep the engine oil from being too contaminated
by the gas. This helped the oil last longer.
But, then came pictures of L.A. smog, and the
smart scientists realized that we could cut down on about
20% of the smog if we didn't let that gas out that we paid
for anyway. So now we have what is called a closed crankcase.
The oil filler cap should not let out any fumes.
And the oil dip stick should also be sealed, in some newer
cars better than some older cars. And we have a fancy PCV
valve or orifice that lets the intake manifold vacuum
recycle and burn that gas we paid for.
Inside the PCV valve is an orifice regulated
by a plug and a spring. When manifold vacuum is high, this
plug is sucked in hard against the spring and we just have
a small calibrated orifice for blowby to flow through. Then,
as engine load increases, the vacuum drops and the plug is
pushed back by the spring and we have a bigger opening for
more crankcase flow.
But if we have no vacuum, the plug is pushed
against the other end by the spring, and we have no flow.
This is a flame arrester in case of a backfire. We
wouldn't want the flame in the intake to spread to the crankcase.
Also in this system, instead of a road draft tube, we have
some sort of vent tube usually running between the
crankcase or valve cover and the air intake or air filter
Here's how the PCV flow goes...
more free info...
The above info is from page 45 of my "Smog Refresher
Course" book. Special offer here.
Electronic information available worldwide, instantly!
to learn how to diagnose quickly and accurately?
Do what the pro's do - use a lab scope! This will significantly
reduce diagnosis time and more importantly increase
accuracy. Never used one before? I will teach you how! And
if you already have one and want some advanced skills, I cover
How good do you want to be at fixing cars? Just OK,
so you can fix the easy ones? Or do you want to be able to figure
out almost anything that comes your way? Thatís the edge using
a lab scope can give you. Let me put it another way. If you
wanted to look at something pretty, would you want an old, faded
black and white photograph, or would you rather look at it with
a video camera on your widescreen TV? Thatís what a lab scope
can do for you that a scan tool canít. Oh, you need a scan tool
nowadays to fix cars. But if you arenít using a lab scope, with
amp probes, thereís a whole world you are missing.
This book is designed to get you into that worldÖ†
Some techs canít use a lab scope at all, and others can
get a couple of patterns up on the screen. But they donít
know how to make it really fly. They get nervous and confused
trying to get a pattern on the screen. When it doesnít
work at first, what do they do? What does the pattern
mean? How do you know if the signal is good or bad?
Without a lab scope and amp probes...there's
a whole world you are missing.
|Thatís what this book is about. You could
call this ďLab Scopes for DummyísĒ, except Iíd probably
get a call from the lawyer of the group that puts out all
those books, and we donít want that.
We keep it simple. The purpose of this book
is to get you measuring all kinds of things with your
lab scope. And I firmly believe that if you canít make
something simple when you explain it to somebody else,
you donít really understand it. Later on, weíll get
into some more complex applications of lab scopes. But
weíll still make that simple, too. (Youíd be surprised
at all the testing you can do that will help you with
| This book is designed for the technician
who doesnít really know how to use a lab scope, also called
a DSO. (Digital Storage Oscilloscope) Or the tech who wants
to take his diagnosis to the next level. Weíre going to
explain these things:
- How does a lab scope work? (in very simple terms)
- When you look at a pattern on the scope, what are
you seeing, and how do you know if it is bad?
- How do you get a pattern on the scope, how do you
do the adjustments to make the pattern look right?
- What do you do when you canít get a pattern on the
screen at all? (A lot of guys have this problem, but
donít admit it to their friendsÖ)
more free info...
- What are some of the different things you can do and
see with the lab scope? (Most technicians donít know
how much diagnosis you can do with an inexpensive scope,
and a few attachments.)
- Where and how do you hook up the scope to the circuit?
Does it make much difference?
The above info is from page 1 of my "Lab Scopes: Introductory
& Advanced" book. Special
offer here. Electronic information
available worldwide, instantly!
|Compared to a Scan Tool:
Many of you are used to working with scan tools. You pull
up the data on a screen, and you read something, let's say
the throttle position sensor. Maybe it says 0.6v. How quickly
can that number change when the throttle changes? On many
scan tools it can take a second or more, right? So, what
happened in between those numbers? Did things happen that
you didn't know about? That can be a problem.
data only shows what the PCM thinks it sees, and
it doesn't update very fast.
Some scan tools let you graph data, so you get the info
updated at much quicker internals. But it still isn't
as fast as you can get from a good lab scope. You could
be missing something. Let's think of an example.
You are driving along in a Ford, you decelerate for
a stoplight, and you hit a chuck hole that causes the
engine to shake. This causes the TPS voltage to go below
your normal 0.6v at closed throttle, down to 0.4v, just
for an instant. (The TPS has started to go bad, but hasn't
set a code yet.)
A lab scope draws
a picture of the voltage...
Now the computer thinks this is your closed throttle
idle position. So when the TPS is back to 0.6v at the
stoplight, the computer thinks you're cruising. So it
keeps the idle speed high. (It's preparing to drop the
idle speed slowly for you when do your next deceleration,
to keep the emissions low.) You have just duplicated the
high idle problem your customer was complaining about,
but will the scan tool have recorded your glitch? Probably
not, with a fast glitch.
Remember, those numbers on the scan tool that just sit
there and don't change, don't mean the...
more free info...
The above info is from page 9 of my "Lab Scopes:
Introductory & Advanced" book. Special
offer here. Electronic information available worldwide,
Should You Listen to Me?
|My name is Steven McAfee. After working as a mechanic
for almost 30 years, teaching for 10 years and assisting
in developing numerous training programs and classes
for both private industry and community colleges (technical
institutes), I can tell you a lot about automotive repairs.
I understand the frustration you experience when you don't
understand what's going on under the hood or the agitation
and insecurity you feel when you can't fix the problem.
How do you find out what's wrong with the car before
you waste money on parts that you hope might
fix the problem? I can help you with that.
I have been priviledged to have factory training from Ford,
Chrysler, Toyota, GM and BMW so I can pass on some of that
information to you.
My first book the "Smog Refresher Course" was written
to help California smog technicians pass their Smog License
Exam but because it has general information about gas analysis,
emission control devices, feedback carburetors, dynamometer
testing and OBDII, people requested I make this information
publically available. I was teaching in California at the time
I wrote this book and I was recently asked to teach overseas
so I am now in New Zealand, enjoying the beautiful scenery and
sharing the knowledge I have of automotive electrical, computers,
emissions and engine performance diagnostics and repairs and
using a lab scope for effective diagnosis. More
about me... See
my special introductory offer here.
I teach entry level to advanced classes in the following
Electrical; Autotronics; Emissions; Basic and
Advanced Clean Air Car Course; Engine Performance; ASE A6 Preparation;
A6 Alternative; ASE A8 Preparation; A8 Alternative; ASE L1 Preparation;
L1 Alternative; OBD II (On Board Diagnostics - 2nd generation);
Fuel injection and computer controls for: Bosch, Chrysler, Ford,
General Motors, Honda, Toyota, Autotronics, ABS Brakes.
See my resume here.
to Help You Succeed
You could spend days searching on the internet looking
for free information hoping it might cover everything
I go over here. Or you could spend a couple of minutes
and get all the information you need delivered to you
instantly. Quickly discover what you need to know so you
too can perform successful auto repairs. To help you get
started I have a special offer for a limited time only
- buy two electronic books together and get a $10
discount off the regular price (Regularly
$24.95 each). The "Smog
Refresher Course" and "Lab
Scopes: Introductory & Advanced" will enhance
your knowledge and help you work more efficiently.
here to order now There is a 100%
money back guarantee on all purchases. Delivery
You get a link to open the books as soon as your order is complete.
And don't worry, if you lose the link, username or password
for the electronic items you ordered, you can get them again
by simply emailing
us (tell us your name, date of purchase and items purchased)
- we will verify your order and gladly send you the information
you need.All e-books need the free Adobe Acrobat Reader to open
them. Most computers already have this. If you don't have the
free Reader, you can get one by clicking here,
and following the instructions from Adobe Acrobat for your computer.
Refresher Course" contains 120 pages packed with
theory, examples and questions. It has 141 sample test
questions and answers. These questions are similar to
what is on the state test. I can't give you the actual questions
- the BAR would skin be alive! Individually priced at only $39.00
for the printed
version (direct from the printers) or $24.95 for the electronic
version, this book is definately worth it.
E-book priced at $19.95 for a limited
time with this special
Scopes: Introductory & Advanced" is 75 information
packed pages and contains lots of screen captures
and pictures to help illustrate procedures. Individually
priced at only $39.00 for the printed
version (direct from the printers) or $24.95 for the electronic
version, this book will open up a new world of diagnosis.
E-book priced at $19.95 for a limited time with this
100 % Money Back Guarantee
No questions asked - if you're not satisfied, simply
return the product and you will get your money back.
Items bought from other companies that are advertized on this
site, like Amazon and Aramark are covered under the return policies
of those reputable companies who stand behind their products
No matter what country you live in, getting the right information
is the difference between success and failure. And that
information is not always readily available. I have changed
books make accessing information fast and easy no matter
where you live in the world. After receiving two e-books, this
is what Victor from Zambia had to say:
"...I also wanted to let you know how much impact those
books you sent me have made in the automobile industry right
here. I call them a blessing because they have really increased
the number of calls I receive in a day for repairs. I told
you I would be the best some day. My dream is comming true.
Even franchised dealers call me for some service. Thanks to
the world of electronics! " Victor T, Zambia
Shawn from Florida had this to say:
"I have recieved my electronic order and have found
your material very useful. Suddenly I felt like I was in high
school again. Most refreshing to get a glimmer of that feeling
again. Life was so simple then. Thank-you..." Shawn,
do I get this information?
Ordering is fast and easy and comes with 100%
money back guarantee. You may click on the Order
Form button on this page or go directly to the section you
are interested in by clicking one of the department links below.
If you're still not sure about ordering, you don't have to
buy a whole book - the Smog Refresher Course is broken down
into shorter articles
(or chapters) ranging in price from $1.59 to $3.49! Try something
cheap, and if you like it, you can always come back and buy
more. And if you don't, you can get your money back by emailing
us (tell us your name, date of purchase and items purchased).
As soon as your order is completed you will receive a link to
you chose. No waiting time. Printed books take
one week to arrive (within the continental U.S.A. and longer
for overseas orders).
California Technicians taking the Smog Check License Exam:
The "Smog Refresher Course " was originally written
to help mechanics in California pass their Smog Check Technician
License Exam by an instructor (Steven McAfee) who assisted
in developing training materials for the Bureau of Automotive
Repair. Many people have written or called to say they have
passed their test after reviewing my information. I'm
glad I can help.
In the Smog Refresher Course, I emphasize Diagnosis,
the area where most technicians have trouble with the test
questions. I try to keep it simple, and maybe a little silly
in places to keep you awake after a long day's work.
You probably noticed how the BAR divides their
Smog Test into nine subject areas. And the knowledge needed
in their diagnosis and repair areas seems so broad it's hard
to know what to study for. Through years of experience teaching
smog preparation classes I have found it most helpful in
diagnosis to cover the following four areas:
1) Five Gas Exhaust Analysis
2) Computer Inputs and Outputs
3) Emission Control Devices
4) Rules and Regulations
All this and more is available in the Smog
Refresher Course book. The information in this book
is also helpful for those preparing for the ASE
L1 test. 2/3rds of the information overlaps.
For example the Exhaust Gas Analysis and Scan Tool (computer
diagnosis) sections are similar to the L1. And the Emissions
Devices section will also help.
This information packed book contains 120 pages of theory,
examples and questions. It contains 141 sample test questions
and answers. These questions are similar to what is on
the state test. I can't give you the actual questions -
the BAR would not be happy with that! At only $39.00
for the printed
version (direct from the printers) or $24.95 for
version, this book is definately worth it and has helped
If you're worried about taking the test, listen to what Charlie
"Steve - I reviewed your information on the internet
prior to re-taking my EA Smog Tech Exam. I am impressed and
appreciate your making available this material. Again, Thanks!"
To get my special introductory offer of the two electronic
books, "Smog Refresher Course" and "Lab Scopes:
Introductory & Advanced" click
here to order now
Ways to Order:
If you want to order printed books by mail or by fax, just
print out this order form,
fill it in, enclose payment and mail or fax it to us. Our address
Automotive Electronics Services
5465 East Hedges Ave
Fresno, CA 93727
All orders must be in US funds. If you pay by check, we have
to wait 7 days for the check to clear the bank before we can
mail your order out. Please note that articles and e-books are
not available using the printable
order form. Articles and e-books
are only available through online ordering.
For schools wishing to purchase multiple copies of any of the
books, we offer school discounts (please contact our printers,
Automotive Electronic Services at (559) 292-3533 or email@example.com).
Schools may order by using the printable
order form or on this website. For those wishing to use
purchase orders we have ISBN numbers for our two most popular
|Smog Refresher Course
|Lab Scopes: Introductory & Advanced
Purchase orders and printable order forms may be faxed, emailed
or mailed to our printers, Automotive Electronic Services at
(559) 292-3533 or firstname.lastname@example.org
Please include your email address so we can confirm receipt
of your order.