Support / Knowledge

Throttle body clean and reseal

May correct:
sporadic idle
Ruff idle
Surging during idle
and IAC error code

If you have read any maintenance manuals about cars particularly foreign cars, most say not to clean the throttle body. The reason given is that the bores in the aluminum are coated and cleaning can remove the coating, doing more harm then good. I myself find this not to be true. Although the bores MAY very well be coated I found that you can clean the main bore and throttle gate if some care is taken during the process. If you look around the air gate on most throttle bodies you will notice a rubbery coating that has been painted around where the brass meets the aluminum wall of the throttle body. This is to make an air tight seal when the throttle is in the fully closed position. An air tight seal is needed so that 100% of the air through the throttle body is diverted to the IAC (Idle air control), without it the engine has limited or no control over engine speed at idle. If you decide to clean your throttle body this seal will most likely be damaged and will need to be replaced.

Cleaning

If you look closely to these two Honda throttle bodies (y7 left, z6 right) you can just make out the black seal around the throttle gate. When cleaning I recommend you take the throttle body off of the intake this will prevent cleaning fluid from building up inside the intake manifold and causing engine damage. Many people just say start the car up and keep it running while spraying carb cleaner into the throttle body. I would not recommend this. Once the throttle body is removed, clean the inside of the main bore with cleaning fluid, Carb cleaner and Kerosene work well also. Use a soft cotton cloth and work your way around inside while holding the gate open. You may also want to clean the IAC valve while your at it. Be gentle and get as much grime off as you can WITHOUT scrubbing.

Reseal

After the TB is cleaned you will need to reseal the throttle gate. To do this I made a mixture of thinned down silicone based RTV gasket. I chose RTV because it is oil and gas resistant and has good heat resistant properties. A solvent is used to thin the RTV, I used lighter fluid to thin mine. Add the fluid to the RTV a drop at a time until it takes on the consistency of paint and can easily be applied with a smallbrush.