Today's engines have been designed
to have more output performance power and lower emissions than ever before. So when the output
of your vehicles engine is compromised it is easily detected. When your vehicle
has low power output it can mean several different things are occurring. You should
know while your car has low performance it could be damaging components while you
drive.
Example: The emergency brake is on and you did not notice, this condition will
burn up the rear brake pads or shoes and cause premature emergency brake failure.
Or, the fuel filter is clogged
causing the fuel pump
to labor which can cause premature fuel pump failure. There are basically two kinds
of low power conditions either the engine is running rough causing low power or
the engine is running smoothly but still has low power. If the engine is running
smoothly but has low power you are in the right place. If your engine is running
rough causing low power please visit.-
Engine Misfires
Car Repair Information Guide
Scan for Trouble Codes - Check to see if the "service
engine soon" light is on, if not continue to the next step. If the "check
engine" (same thing as a service engine soon light, different manufacturers
call it different things) light is illuminated you need to have the computer scanned
for trouble codes. Use a simple scanner tool to
retrieve trouble codes and check if they relate to the specific problem, like a
fuel pump circuit failure code. If a trouble code is present but does not pertain
to the immediate problem like an EVAP code ignore it until a later time, after the
engine is running properly. The reason we repair non-related codes after the engine
is running properly is because sometime false codes can be triggered by a
poorly running engine.
Once the engine is running properly the code present might cycle and turn itself
off. You might say "if the engine isn't running right shouldn't it have a check
engine light and a trouble code?" Sometimes conditions occur that will not be detected
by the computer, example: if the intake or exhaust valve operation fails the computer
cannot detect the failure because the problem is not sensor related, so the engine
has no power and the computer thinks everything is ok with no codes. If the trouble
code retrieved relates to a low power like a
mass air flow (MAF)
sensor or ignition coil system failure repair these problems and re-test system.
If no trouble codes are present proceed to the next step.
How to Scan for Trouble Codes Video
Checking the Air Filter - A
plugged air filter not allowing
the proper amount of air into the engine. If air is not allowed to enter the engine's
intake it will limit the engine power output. To check your engine air filter open
the hood and remove the air filter from its housing and inspect, replace as needed
and recheck.
Replacing an Engine Air Filter Video
Check the Fuel Filter - Several conditions can cause low power,
one of the most common reasons is a
clogged fuel filter not allowing
the proper amount of fuel pressure and volume into the fuel injection system.
To check for this condition remove the fuel filter and drain excess fuel from the
filter, next wipe any excess fuel from the filter. By blowing through the filter
you can determine if the filter is clogged, you should be able to blow through it
very easily. If you cannot blow through it or it is difficult replace the fuel filter
with a new unit and recheck system. Some fuel filters utilize a special release
tool available at a tool store. If the fuel filter is okay proceed to the next step.
Testing Fuel System Pressure
Check Fuel Pump Pressure and Pressure Regulator -
Fuel pump is worn providing
low fuel pressure to the fuel injection system. A fuel pump that is faltering providing
low system fuel pressure/volume will cause low power. Your car's engine depends
on constant fuel under pressure to supply the fuel injection system properly. Your
car's fuel pump performs this action and is located in or near the gas tank. The
injection system meters fuel through the injectors and into the engine. Many engine
run drivability problems can be related to a weak or failing fuel pump. Problems
can range from hard starting in the morning, low power and
stalling while driving. Most vehicles have
a fuel pressure test port somewhere on the fuel rail, use a flashlight to locate
it on your engine or consult a repair manual. Also test the fuel pressure regulator
performance; if the regulator is stuck or leaking the engine will not receive the
additional fuel needed for power. If the fuel system pressure is okay proceed to
the next step.
Checking a Distributor Ignition Systems - If your car has a
DIS (distributor-less ignition system) skip this step. Ignition timing is very important
in achieving maximum power from your engine. If the
timing is adjusted too far advanced
or retarded (in front or behind the timing mark) in relationship to the engine crankshaft
it will have low power output. To check your engines timing adjustment a timing
light is needed. Once the timing light is hooked up to the battery locate the under
hood emissions sticker that has the engine timing specification and instructions.
If you can't find the under hood sticker or it is illegible consult a
car repair manual.
If the engine timing is ok proceed to the next step. If the engine timing is way
off (20 degrees or more) check the timing belt or timing chain, the crankshaft camshaft
correlation might be off.
Checking the MAF, (mass air flow) and MAP (manifold absolute pressure)
Sensors - The MAF or MAP sensors help the
PCM computer determine
how much air the engine is consuming and distributes the proper amount of fuel.
If these sensors become weak they can misread and cause the PCM to think the engine
is turning slower than it is, in turn giving the engine less fuel and producing
less power. You might say wouldn't the computer see a problem and illuminate the
service engine soon light?- MIL (malfunction inductor lamp) and the answer is not
always. The PCM is designed to detect a shorted sensor or a sensor that is
way out range. If the sensor is a little off but it is still within range the service
engine soon MIL will not illuminate. This test procedure is simple but unique to
each car, for the exact test procedure you will need a repair manual.
Check for Severely Worn or Misadjusted Spark Plugs - Engine
timing is crucial to power output, if the
spark plugs are severely worn
or have a misadjusted air gap the timing of the spark can be delayed or ineffective
causing power loss. To check your engine's spark plugs wait until the engine is
cold, then remove any spark plug and inspect. You are looking for the correct air
gap between the electrodes, if the gap is incorrect remove all spark plugs and recheck.
If the spark plugs are ok proceed to next step.
Checking the Timing belt or Timing Chain Settings - The crankshaft
and camshaft must stay in proper correlation. The procedure for checking crankshaft
to camshaft correlation varies on each car. You will need to gain access to the
timing belt or chain marks. Once
you have gained access check your engine timing marks,
timing belt or timing chain setting.
Correct as needed and recheck engine, if the timing correlation is correct proceed
to next step.
Checking the Exhaust System for Blockage - A
plugged catalytic converter
can cause low engine power by not allowing the engine exhaust to exit the engine
properly. To check for this condition take your car for a 15 minute drive allowing
the exhaust system to warm, park the car safely and use a pocket IR thermometer
laser temperature reader to measure the temperature of the exhaust pipe entering
the catalytic converter and the exhaust pipe leaving. The temperature should be
lower going into the catalytic converter and hotter leaving the catalytic converter,
if not there may be a restriction inside the converter.
Plugged Catalytic Converter from Broken Catalyst Material
Example: the temperature entering the catalytic converter is 300 degrees and
exiting the catalytic converter is 450 degrees. This means the catalytic converter
is working properly, if the temperature is the same or lower the catalytic converter
is not working and is probably plugged.
Pocket IR Thermometer Laser Temperature Reader
Check the Engine Compression - As the engine depends on
compression to ignite the
fuel air mixture. If an engine has major wear is will not produce the proper amount
of power. A compression test can be performed to check for wear or internal damage.
A compression gauge is needed to test the engine cylinders. There are two
types of gauge styles, one threads into the spark plug hole which is more accurate.
The other style of gauge is designed with a rubber plug that is meant to be pressed
against the spark plug hole, this style of gauge is difficult to use.
Checking the Transmission - Sometimes the engine will have good
power but it is not getting to the drive wheels. If you are driving and the engine
sounds like it is working hard but the car is not going anywhere it could be the
transmission clutch or clutches are slipping.
When a clutch or clutches in a manual (standard) or
automatic transmission
wear they can slip not allowing the power from the engine to be transferred to the
drive wheels. In this case the only fix is to replace the clutch or clutches depending
on automatic or standard transmission. If this is not the condition continue to
next step.
Slipped Harmonic Balancer - Some cars have an ignition trigger
system that bases the engine timing off of the
crankshaft harmonic balancer.
If this balancer comes loose it can cause the keyway in the crankshaft to dig its
way into the balancer causing the timing to retard causing low power. To check for
this condition remove the harmonic balancer and inspect, replace if needed and reassemble.
If further assistance is needed, our certified car repair technicians are ready
to answer your car questions.
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