The throttle bore or throttle actuator as they are called it on newer cars is
used to meter the engine air intake thus controlling the engine RPM and power
output. The throttle actuator is a normal service item and each manufacturer has
their own design when it comes to the throttle system of an engine, the
principle remains the same.
What goes wrong?
As the engine operates large volumes of air are processed which leaves behind
deposits that can hinder the actuators operation and deflect air flow in an
undesirable manner causing the engine to
and limp mode conditions. When
these deposits called coking become sever enough the
car's computer will
detect a correlation mismatch and reduce the power of the engine as a safety
Throttle Actuator Service
Can help stop the engine from stalling at idle
Fix a stumble off idle
Is part of a Tune up
Will cause the engine to go into limp mode
May need reprogramming if serviced incorrectly.
Can alleviate hard starting
Can normally be done in about 20 minutes
Is a DIY service.
There are generally three types of throttle actuator.
Cable Operated - This is the most forgiving of actuators and will need
no special care other than service.
Gen 1 Electronic - (About 2000 to 2009) To service these actuators you
must disconnect the battery to avoid programming issues.
Gen 2 Electronic - (About 2009 to present) These units must be serviced
with the wiring connector still connected to the actuator (it can be
unbolted) and it cannot be forced open or it will cause programming issues.
In the shop one technician will open the throttle actuator with the key on
while depressing the gas pedal while an additional technician performs the
Where is it?
The throttle actuator is located at the intake manifold air inlet
between the air intake tube and main intake manifold body on top of the engine
toward the front in most cases. Some throttle actuators have engine coolant that
runs through the unit to help heat it help to improve cold starts and improve
What's the cost?
The location of the actuator will determine the cost of the service which is
typically about $65.00 to $95.00 US if the job is done at a shop. Supplies to do
the work includes a can of throttle bore cleaner (carburetor cleaner) and a shop
towel, for the DIYer, about $15.00 US.
Start by disconnecting the battery, this will prevent triggering
computer issues when doing the repair. Locate the air intake tube and loosen
the clamps and mounting bolts to remove it. (Leave the wiring connected if
newer than 2009). Older vehicle's utilize a throttle cable which must be
removed, along with transmission and cruise control cables.
Remove the actuator wiring connector which could have a safety
clip that will need to be removed before the connector can be disconnected.
Some actuators have coolant running through them which will need to be
drained and then
refilled once the job is complete. Disconnect the hoses and continue
removing the mounting nuts. Remove the sealing gasket or "O" ring seal and
clean or replace. Use carburetor cleaner and a shop towel to clean the
Clean the throttle
actuator bore housing and butterfly both the front and back sides including
the pivot shaft. Looking from the rear of the throttle bore coking deposits
are observed which is caused by impurities in the air causing the engine to
idle erratically. After installing the throttle bore, insert and evenly
tighten mounting bolts or nuts. Reinstall vacuum, bypass and breather tube
lines while reconnecting the electrical connectors. Reconnect throttle
cables and reinstall the air intake boot, clear any
codes if necessary.