Question: Smog
test showed that the idle for my 1993 Mazda MX6 is set to
high. [Timing is at 10 degrees BTDC at 1150 rpm and 10 degrees
BTDC +/- 3 degrees st 850 rpm +/- 100 rpm.] The car passed the
emissions test. My questions
follow: Will retarding the
timing be sufficient to pass the smog test? or will the
emissions increase as a consequence of reduced rpms?
Will a tune up take care of the
timing or is it more complicated requiring a visit to Gold
Shield repair center?
Answer: Question is... is the timing set to the manufacturers
required setting? If it is, the high RPMs may be due to
perhaps an idle air adjustment, or other adjustment
your particular vehicle may require effecting engine idle. If
the timing is off, then by all means, correct it. Remember
advancing timing will causes higher RPMs and higher emissions.
Retarding timing (slightly) will lower idle and emissions as
well. But be careful with retarding timing. Too much, and the
emissions will skyrocket. Also keep in mind, you have to stay
within the 3 -/+ mark. And yes... a tune up should include a timing
adjustment.
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Question: I have a lifted
2000 Chevy Silverado 2WD on 40 in. tires. This is the first
time I have to get the truck smogged since the lift. I blew
the rear end out not too long ago and had to get the gears
redone. Now when I drive the speedometer is a little off when
I drive; not too much on the streets its more when I am on the
freeway. It is about 5-7mph off on the freeway and when I go
faster the difference just increases. This does not happen til
I start to go above 55mph. Will this hurt me when I go get the
truck smogged.
Answer: The 40 tires are
going to make your vehicle's engine work harder on the
dynamometer during the smog test. This in turn is going to
produce more emissions. On a sound operating engine, the tires
might not effect emissions to a failure, but assuming your
vehicle's engine has a few miles on it and maybe is running at
a slightly less then maximum efficient combustion, these tire
will pose a smog threat. Our recommendation is that you have
the vehicle inspected with the original manufacturer recommend
tire size/s.
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Question: I need to get a smog check (2001
Ford Ranger), but I have a broken speedometer. Will the smog
station still run the test on my vehicle?
Answer: Yes, you can still
pass the smog test. The speedometer is not part of the smog
test.
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Question (a): I have a 1996
Chevy S10 4.3L auto 2wd. No check engine light on, runs ok.
103,000 miles. At last smog test, CO and NOX passed well, but
HC was at upper limit. What could be causing this, and what do
I do to fix it?
Question (b): I had a 1998
Toyota 4runner fail smog today . The ppm was too high at 15
mph. They wanted 100 dollars to diagnosis plus repair costs.
Do you have any idea what I should try to fix on my won first.
I changed the pvc valve, oil change and new air filter. Is
there something else I should fix ? Also I didn't really drive
the car very long before test , could that have been the
failure?
Question (c): My car is 1992
Pontiac Grand AM ES, Quad-4 Engine inline 4 DOHC. My car don't
have E.G.R. I was shocked. I know EGR will help low NOx ppm..
but how can I pass emission test without EGR. My car is only
just almot 72,000 mile. I know other possible is catalytic
converter (CC) but I doubt because cc is still newer due to
low miles 72,000.
Answer: Vehicles fail their
smog inspection for different reasons based on the variety of
emissions control systems used on production vehicles. We
recommend using our SmogSmart VIR Report system. We'll be able
to give you a much better idea of what your vehicle's emission
problem might be. The SmogSmart VIR Report system will ask you
to fill in all the information our report system &
technicians need to effectively evaluate your vehicle's
emissions failure. You may also use the "Additional
Information" section of the blank form to include detailed
comments. To obtain your vehicle's SmogSmart Report, please
visit the On-Line Evaluations Page at
www.smogtips.com/smog_evaluations.cfm
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Question (a): I
have 1979, 280SE Mercedes
MBZ. My car failed in smog test because NO (PPM) measurement was 1933
at 15mph, which exceeded the maximum value of 1277. What
I need to do to my car to bring down the NO measurement to an
acceptable value?
Question (b): My car (2001 Infinity) failed
smog at a test only station. It failed the Nitrogen
component. It has 1100 PPM. I think allowable was
in the 700-800 range PPM. The car passed on the other smog
categories. What part of the smog system should I
concentrate on if it failed the Nitrogen component.
Question (b): I have a 94 Geo
Prism that has no EGR system and failed emmisions with
excessive NOx & no computer codes listed nor check engine
light. What are likely causes.
Answer: There are several
reasons vehicles encounter NOx failures. The most common is
the malfunctioning EGR system (if a vehicle is equipped with
this component). EGR stands for exhaust gas recirculation. And
that is exactly what this component does. The EGR system
recirculates burned up exhaust gases back into the combustion
chambers. Since these recycled exhaust gases have already been
in the combustion chambers once, they have burned up most of
their fuels, means there is now much less real fuel in the
chambers to ignite. This keeps the chamber temperatures down
and thus reduces NOx emissions. The EGR valve should be
inspected to insure its proper operation.
A working valve should be able to open its
passage using manifold vacuum. Manifold vacuum is created
during the engine's intake cycle. The high demand for air
during this cycle creates a vacuum within the engine's intake
manifold. This vacuum is then used to control several
important functions within the vehicle, including controlling
the EGR valve. Some vehicles even rely on this vacuum to
control their heating and air-conditioning components. The EGR
system is prone to collecting carbon build-up. Some vehicle
manufacturers recommend cleaning this component an a regular
basis. Another NOx causing problem: Lean fuel mixtures due to
vacuum leaks may also cause high NOx. A “lean fuel mixture” is
when the engine receives less fuel then is necessary to obtain
clean combustion. Vacuum leaks are open passages, normally due
to defective gaskets or vacuum lines, between two engine
components. These leaks will allow the suction of additional
and un-metered air (oxygen) into the combustion mixture or
exhaust (depending on where the vacuum leak is located)
disturbing pre/post fuel combustion and increasing NOx
emissions. Vacuum leaks can be difficult to locate if they are
present at locations not easily seen. Bad engine cooling
causes high NOx: Engine cooling problems may cause high NOx
also.
If your engine's cooling system is not working
efficiently, chances are there is an excessive amount of NOx
being created. Remember NOx (Nitrogen Oxides) is created only
when an engine's combustion chamber temperatures reach over
2500F. A bad cooling system will create NOx. For this reason
you want to make sure your vehicle's temperature gauge is
always normal and that your cooling system is working
properly. Got high miles? High compression can cause high NOx
too: High amount of carbon build-up within your engine's
combustion chambers will cause increased engine temperature
and high NOx. Carbon build-up normally develops in an engine's
combustion chambers over some period of time. High increase in
carbon build-up causes increased cylinder compression, which
causes high temperatures, which result in high NOx
emissions.
Keep in mind this problem is usually seen in
vehicles with over 200,000 miles. The solution to this problem
is called an Engine DeCarbonizing. It usually costs around two
labor hours at a smog repair station. It will remove a good
amount of carbon of your engine's piston heads and valves.
This will increase combustion space, lower compression and
lower NOx.
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Question (a): If I have a car
(97 Mercury) that has quite a few problems so that it will not
pass a smog check, what can I do?
Question (b): I have a Mazda
Protege 1994 and it does not pass the smog check at all.
Every mechanic won't tell me what is really wrong so that it
can pass. What should I do?
Answer: The next step if
to have a certified smog repair station take a look at your
car. You should give them the failed report, but I'm sure they
will want to run their own tests also. Either way they will
charge a diagnostic fee to figure out what the problem is.
This is normal. I would just ask the station owner if he/she
will guarantee the repairs. In other words, if they say the
car needs a CAT, and you let them replace it, will they
guarantee your car will pass? So just ask these questions and
if the answers make sense then go for it. Some times it is
possible not to be able to promise a passing car. Some times
the problems a vehicle has are just to many and by replacing
one component there is no guarantee to pass.
