Step by step guide on how to troubleshoot and repair an automotive engine that
has low power output, this information pertains to combustion engines.
Difficulty Scale: 5 of 10
Begin with the vehicle on level ground, engine off, in park with the emergency
- An engine's air filter is meant to
impurities and can become clogged resulting in low air intake and low power.
Removing Air Filter
Step 2 - If engine problems exist and the service
or check engine light is on, use a code reader to retrieve the codes to make necessary
Step 3 - If an engine is running poorly it can
result in low engine power output, an engine tune up or fouled spark plug can cause
engine misfire performance issues.
Check Engine Light
Step 4 - The fuel system filter is designed to
remove particles from the fuel itself, when a filter becomes plugged the system
fails to supply pressure to the injectors, this filter must be replaced at regular
intervals to maintain proper performance. (Note: Some vehicles fuel filter is
inside the fuel tank and is non serviceable.)
Fouled Spark Plug
Step 5 - A fuel pump is designed to supply a consistent
pressure to the fuel injection system, when this pump becomes weak it can lose this
pressure resulting in low fuel pressure causing the aforementioned low power output.
Replacing Fuel Filter
Step 6 - A catalytic converter is designed to
incinerate excess fuel remnants resulting in cleaner engine exhaust output
gasses, if the unit bcomes clogged or broken the engine's power will be reduced while restricting exhaust
Fuel Pressure Reading
Step 7 - A mass air flow sensor measures the
volume of air consumed by the engine at any giving time, this sensor is subject to contamination
which can effect the data feedback to the computer causing low engine power.
Step 8 - Engine compression is directly related
to engine power output if this compression is low due to wear or improper crankshaft
to camshaft correlation the engine will have low power.
Mass Air Flow Sensor
Step 9 - The crankshaft and camshaft must stay
in proper correlation, if a timing belt or chain is improperly installed or becomes
loose and jumps a tooth or two the engine will produce less power, disassemble the
timing cover to check timing marks
Step 10 - This problem pertains to older engine
that utilize an adjustable distributor. If the timing is adjusted too far
advanced or retarded (in front or behind the timing mark) in relationship to the
engine crankshaft engine will have low power output. To check the ignition
timing adjustment a timing light is needed. If the engine timing is way off ( 20
degrees or more ) check the timing belt or timing chain, crankshaft camshaft correlation.
Timing Belt Engine Cutaway
- Occasionally the engine will feel
like it has good power,
but its not getting to the wheels, this condition is caused by transmission slip.
Both, standard and automatic transmissions retain a clutch or clutches that when
become worn through usage, can lose their grip and slip causing heat due to the
transference of energy developed from the engine while failing to propel the vehicle.
ignition timing is based off of the crankshaft harmonic balancer, which can
become loose causing the crankshaft wood-ruff key to dig into the balancer timing (location) slot causing the timing to
become retarded causing low power, to check for this condition remove the harmonic balancer and
Computer sensors operate within a prescribed specification, if these sensors become
weak they can effect the engine power output without the computer detecting a problem,
these half broken sensors need an data input scan tool to be detected and will cause havoc until replaced.
Article first published 2016-02-04