Do I Need a Throttle Body Service
The selling of throttle body services by technicians working on a commission basis has been popular for decades. There is no question that a throttle body will get dirty during normal operation and that cleaning them is something that can be done. The question is should it be done. This article will explore how the throttle body works and why it gets dirty. In addition, review some telltale signs when servicing the part can be beneficial.
How a Throttle Body Works
Air enters the intake manifold to be mixed with the fuel charge. The throttle plates allow the driver to control the amount of air flowing in providing variable engine speed and power. The throttle body is also responsible for metering air when the driver’s foot is off the gas pedal. The metering is controlled by the main computer through an output device known as the IAC (idle air control) valve. This is a stepper motor valve that opens and closes a passageway. The computer monitors the RPM (revolutions per minute) through engine position sensors and continuously adjusts air flow at closed throttle.
Why the Throttle Plates Get Dirty
If the engine just pulled in outside air the throttle would stay clean. However, car makers decided to use the naturally occurring vacuum provided at the air inlet hose to vent the crankcase. Here they pull fumes from the crankcase area to be mixed with the fresh incoming air. It’s beneficial for many reasons including fuel economy, emissions reduction and prevents a buildup of pressure inside the engine that could blow out gaskets. The downside of this procedure is the fumes contain oily residue and carbon deposits from post-combustion. This is what collects on the throttle plates.
Do You Need Throttle Service
As dirt and carbon buildup on the throttle, passageways and around the IAC valve the computer has the capability of compensating for this naturally occurring residue by backing off the IAC to make up for the smaller passageway. This can also allow the mechanic to see how dirty it is by using a scan tool to pull up the IAC position measured in steps. Perfectly clean the steps would be about 10 to 15. A throttle body having heavy carbon build up could read above 40 steps and still idle okay.
To answer the question do you need a throttle body service depends on several factors. Most important is the age of the vehicle and the miles on the engine. Since the crankcase is being vented through the throttle body a worn engine will send more dirty fumes past the throttle plates. Also the design of older engines made them more sensitive to the buildup of carbon in this area. Engine performance problems such as part throttle hesitation or unstable idle are more likely to occur on vehicles from the late 80s and 90s then ones built in the last couple years.
How to Clean the Throttle Body
This is not a one-size-fits-all operation because location will vary with year make and model. Some cars allow easy access where removal is not necessary to perform a good cleaning. On other vehicles it may be necessary to remove the assembly. The throttle body mounts to the intake manifold or intake Plenum. When removal is performed professional mechanics recommend using a new sealing gasket when reinstalling it. This is a critical seal because leaks will allow uncalibrated air to enter the engine. You can obtain these from any manufacturer dealer in-house parts department.
After the assembly has been removed from the engine it’s recommended to remove the IAC motor and throttle position sensor because these plastic parts are easily damaged by the harsh liquid cleaners. The throttle can be operated to access the dirt and carbon on both sides of the plate and the airway passages. They make specialized throttle body cleaner that is effective and dries quickly. It is nice to have compressed air to blow out any passageways.
Just because a mechanic recommends a throttle body service doesn’t mean you have to say yes. If the automobile is running fine with no hesitation or idle issues ask the shop why they’re recommending it. The older the vehicle and the more miles on the engine will coincide with the likelihood the service will provide any benefits. Shops claiming the service will bring increased fuel economy and better performance on a vehicle that is not suffering from any of these problems are probably more interested in selling something than improving how the engine runs.