What is OBDII?
OBDII is a second-generation onboard diagnostic system for detecting
emission failures. It is required by federal law on all 1996 cars
and light trucks.
The first OBDII systems were actually introduced back in 1994
on the Buick Regal 3800 V6, Corvette, Lexus ES3000, Toyota Camry
(1MZ-FE 3.0L V6) and T100 pickup (3RZ-FE 2.7L four), Ford Thunderbird
& Cougar 4.6L V8, and Mustang 3.8L V6. In 1995, it was added
to Chevy/GMC S, T-Series pickups, Blazer and Jimmy 4.3L V6, Ford
Contour & Mercury Mystique 2.0L four & 2.6L V6, Chrysler
Neon, Cirrus and Dodge Stratus, Eagle Talon 2.0L DOHC (nonturbo),
and Nissan Maxima and 240 SX.
Not all of these are fully OBDII compliant, but they do include
most of the major diagnostic features found on the '96 models.
OBDII is the offshoot of an earlier system developed back in
1988 for California cars. The original California OBDI system
had limited capability and only monitored the oxygen sensor, EGR
system, fuel delivery system and engine control module.
OBDII is a much more comprehensive and complex system that does
things heretofore thought impossible -- things like detecting
engine misfires as they occur, and tracking other problems that
can cause increased emissions that aren't necessarily the result
of a sensor or component failure.
The OBDII system is designed to turn on the Malfunction Indicator
Lamp (MIL) anytime a vehicle's hydrocarbon (HC), carbon monoxide
(CO), oxides of nitrogen (NOX) or evaporative emissions exceed
1.5 times the federal test procedure (FTP) standards for that
model year of vehicle.
The lamp should indicate anytime random misfires cause an overall
rise in HC emissions, anytime the operating efficiency of the
catalytic converter drops below a certain threshold, anytime the
system detects air leakage in the sealed fuel system, anytime
a fault in the EGR system causes NOX emissions to go up, or anytime
a key sensor or other emission control device fails. So the MIL
light on an OBDII-equipped vehicle may come on even though the
engine seems to be running normally and there are no real driveability
problems.
The main purpose of the MIL lamp on OBDII-equipped vehicles,
therefore, is to alert motorists when their vehicles are polluting
so they'll get their emission problems fixed. The light will still
come on if there's a sensor failure or fault in the computer or
other monitored system. But most MIL lights will be emissions
related -- which means a potential increase in emissions-related
repairs and parts sales for the aftermarket.
For now, though, most OBDII vehicles are still under warranty.But within the next two years, we'll start to see the benefits of OBDII in increased emissions repair work and parts sales. The federal emissions warranty is now only 2 years or 24,000 miles on all emission, ignition and fuel related parts, with the exception of the engine computer and catalytic converter which are now covered by an 8 year/80,000 mile warranty. So we should get more of the emissions work and parts sales that's currently going to the new car dealers.
Will OBDII play a role in emission testing?
You bet it will. Regulators are adding the OBDII MIL lamp to the list of things that will be checked when newer vehicles undergo an emissions test. If the MIL lamp is found to be on when a vehicle is tested, it won't pass even if its tailpipe emissions are still within acceptable limits.
The problem with most of today's vehicle inspection programs
is that they were developed back in the 1980s to identify "gross
polluters."
The tests were designed primarily to measure idle emissions on
carbureted engines (which are dirtiest at idle), and to check
for only two pollutants: unburned hydrocarbons (HC) and carbon
monoxide (CO). The pass/fail cut points that were established
for the various model years were also made rather lenient to minimize
the number of failures. Consequently, a lot of late model vehicles
that shouldn't pass an emissions test slip through anyway.
That's where OBDII comes in. It's sort of like an onboard policeman.
It blows the whistle (lights the MIL lamp) anytime emissions become
a problem. Since most states have gone to biennial emissions testing,
an emissions problem could go undetected for quite a while.
But with OBDII, there's no missing the problem because the light
comes on anytime a serious emission failure occurs, or after a
second trip during which the same kind of emissions problem repeats
itself.
The question is, will motorists ignore the MIL lamp or have
their emission problem fixed? We hope the latter.
Proposals for a third generation OBD system (OBDIII) for possible
introduction in the model year 2000 are now being considered.
The new OBDIII system would take the repair decision away from
the consumer by reporting the emissions problem direct to authorities
via a radio, cellular or satellite link. The technology to do
so is readily available today.
For about $50 per vehicle, a small transponder could be added
to the OBDII system that would report the vehicle's VIN number
and emissions status to a roadside transmitter or remote receiving
station.
If the OBD system detected an emissions problem, it would be reported
and the motorist would receive an official notice in the mail
to have the problem fixed within 30 days and to bring the vehicle
in for an emissions test.
What makes this approach so attractive to regulators is its
effectiveness and cost savings. Under the current system, the
entire vehicle fleet in an area or state has to be inspected once
every year or two to identify the 30 percent or so vehicles that
have emissions problems. With remote monitoring via the onboard
telemetry on an OBDIII-equipped vehicle, the need for periodic
inspections could eventually be eliminated because only those
vehicles that reported problems would have to be tested.
On one hand, such a system could save motorists the inconvenience
and cost of having to undergo an annual or biennial emissions
test. As long as no emission problems were detected or reported,
there'd be no need to undergo a test. On the other hand, should
an emissions problem arise, they'd have to get it fixed.
A prototype OBDIII system built by GM Hughes Electronics has already been evaluated by the California Air Resources Board. The system uses a roadside transmitter to interrogate vehicles as they pass by. The system is reportedly capable of retrieving information from up to 8 lanes of bumper-to-bumper traffic whizzing by at speeds up to 100 mph!
Does OBDII add any new emission parts?
Yes. New parts on OBDII-equipped vehicles include:
These allows the PCM to be reprogrammed with revised or updated software changes using a terminal link or external computer. Currently, this is a "dealer-only" service but eventually it should come to the aftermarket.
Are special tools needed to work on OBDII-equipped vehicles?
Yes. An upgraded OBDII compliant scan tool is a must -- which
means an upgrade kit or a whole new scan tool in most instances.
Because of the hardware and software changes introduced by OBDII,
it isn't possible to simply upgrade an existing scan tool with
a data cartridge alone.
A hardware adapter is also needed, which brings the price of updating an existing scan tool to about $500 for certain popular brands. The other option is to simply trade-in the old scan tool for a new OBDII-compliant scan tool. This is the route many technicians will ultimately take considering how fast the technology keeps changing today.
Have OBDII-equipped vehicles experienced any unusual problems?
Yes. On '96 General Motors J-, N- and H-body cars, several rental
fleets have encountered problems with the MIL lamp coming on because
motorists and fleet personnel haven't been using the correct refueling
procedure when filling the fuel tank with gas. On these cars,
the OBDII system applies vacuum to the evaporative emissions control
system to check for air leakage.
If the gas cap isn't tight or the tank is filled while the key
is on or the engine is idling, it can trigger a false P0440 code
causing the MIL light to come on. GM has not issued a technical
service bulletin on the problem, but it is advising its dealers
and fleet customers to reflash the EEPROM with revised OBDII programming
that waits to check the evaporative emissions system until the
vehicle is in motion.
Bad gas has also been causing some false MIL lights. When the
vehicle is diagnosed, the technician finds a P0300 random misfire
code which would normally be set by a lean misfire condition due
to a vacuum leak, low fuel pressure, dirty injectors, etc., or
an ignition problem such as fouled plugs, bad plug wires, weak
coil, etc.
The OBDII self-diagnostics tracks misfires by individual cylinder, and considers up to a two percent misfire rate as normal. But water in the gas or variations in the additive package in reformulated gasoline in some areas of the country can increase the misfire rate to the point where it triggers a code.
Should I recommend long-life plugs or standard plugs?
It depends on the application. Long-life plugs don't cost much
more than standard plugs, and last two to three times as long
as standard plugs (up to 100,000 miles versus 30,000 miles). Long-life
plugs are also a good choice for any application where the plugs
are buried and hard to change (most full-size vans with V8 engines,
and the rear plugs on most transverse-mounted V6 engines in front-wheel
drive cars and minivans). Long-life plugs would be a waste of
money, though, in an engine that had an oil fouling problem. The
long-life plugs probably wouldn't last any longer than standard
plugs, and would soon become fouled by thick, oily carbon deposits.
Short trip driving is extremely hard on all types of plugs.
If the engine is only driven a mile or two per trip, it doesn't
run long enough to burn the fuel deposits off the electrodes.
Under such driving conditions, the plugs will start to misfire
long before they would in an engine that is driven for longer
distances. Switching to a hotter spark plug (higher heat range)
would be recommended here to reduce fouling.
For performance applications, there's a third option: performance
plugs.
Some spark plugs feature specially-modified electrodes such as
a split outer electrode, pointed outer electrode, multiple electrodes,
or a fluted center electrode.
These designs improve firing reliability to minimize the intermittent
misfires that normally occur in every engine.
Performance plugs usually command a premium price, but often make a noticeable improvement in idle quality, fuel mileage and all-round driving performance. Service life is about the same as standard plugs.
What do I need to know to sell fuel injectors?
Injector replacement should only be necessary if an injector
has failed, is worn out or can't be cleaned. Dirty injectors continue
to be the most common type of problem. But "dirty" is
actually a misnomer because it isn't dirt that clogs the injector
but a buildup of fuel varnish deposits. The olefins (heavy waxy
substances) in gasoline form deposits when fuel evaporates in
the injectors. This occurs every time the engine is driven and
shut off. So frequent short trip driving can lead to a rapid accumulation
of injector-clogging deposits -- especially if a motorist runs
the cheapest gas he can buy. Most premium grade fuels contain
sufficient detergent and other additives to keep the injectors
clean. But many low grade fuels do not.
When the injectors get dirty, the normal cone-shaped spray pattern
develops streamers that inhibit proper fuel atomization.
Deposits also restrict the size of the opening and reduce the
amount of fuel that's delivered per squirt. This leans out the
fuel mixture and causes hesitation, lean misfire, rough idle and
similar driveability symptoms.
Dirty injectors can often be cleaned by pouring a fuel additive
in the tank.
Most professionals recommend on-car cleaning which involves feeding
pressurized solvent directly into the injector fuel rail to flush
out the injectors.
Off-car cleaning equipment that requires removing the injectors
is also available, and can often rejuvenate dirty injectors that
fail to respond to fuel additives or on-car cleaning.
But sometimes the injectors are too badly clogged to be fully
restored by cleaning. If a power balance test shows significant
differences between cylinders after cleaning, or if an injector
flow test reveals restricted fuel delivery or a poor spray pattern
after cleaning, replacement is the only option.
Injector replacement is also necessary if an injector is worn
(which is not unusual in high mileage engines) or has failed electrically
(shorted or open).
A working injector will make a buzzing noise as it cycles open
and shut, but a dead injector will remain silent.
Accurate diagnosis of injector problems is essential before
any parts are replaced to rule out other possibilities.
A bad wiring connector or computer circuit can render an injector
inoperative. Air leaking past the rubber O-ring seal at the base
of an injector can also mimic the symptoms of a clogged injector.
Replacement injectors are available in two varieties: new and
remanufactured. New injectors for a domestic application typically
retail for $60 to $100 each, while ones for import applications
may be as high as $125 to $175 each.
Remanufactured injectors, on the other hand, provide a more affordable
alternative to new with prices ranging from $20 to $50 or more.
It's important to note that many injectors are color coded.
The flow characteristics, spray pattern and calibration of a particular
set of injectors is matched to a specific engine application,
and has an important affect on engine performance and emissions.
So it's extremely important to make sure your customer gets the
correct replacement injectors for the application. Injectors can't
be interchanged from one application to another even when they
look the same on the outside. Installing the wrong injectors may
make the fuel mixture run excessively rich or dangerously lean.