This is just a public service message that you should read if you own any of the following cars (I've also included advice for other brands towards the end):
- 8th Generation Civic
- 3rd Generation City (current model in other words)
- Accord CL-7/CL-9
- Accord Inspire (current model)
Do not clean the throttle body of your cars from anywhere aside from a Honda 3S dealership. The reason for this is quite simple:
- The throttle system on these cars is a fairly advanced drive-by-wire system (DBW) which learns its throttle opening and and idle settings over the period of driving the car. It also adapts to the carbon buildup around the throttle opening over time by a learning process and adjusting throttle sensitivity accordingly.
If you end up cleaning this by yourself or at a non-Honda workshop the results will be as follows:
- The car will lose its idle settings and the RPM will become erratic
- The throttle response will be extremely twitchy and the car will become "nervous" randomly when giving or releasing throttle.
- This behavior will continue and the car will become an irritation to drive until its reprogrammed at Honda
The only way to clean the throttle body is to go to a Honda dealership, where they will clean the throttle body and then reprogram the car's throttle using the HDS (Honda Diagnostic System), this is a 15 minute computerized procedure which you cannot replicate anywhere else unless you have the HDS programmed for these cars.
For CL-x series owners
I am assuming this also applies to your cars, since the cars mentioned otherwise have carry-over systems which were originally designed on the CL series of Accords.
For Toyota Corolla owners (current generation cars with electronic throttle)
Your cars most likely are unaffected by this since they have an electronic throttle instead of a drive-by-wire. While similar to a drive-by-wire this system is different because it doesn't have a computerized learning system like the cars mentioned above. Therefore technically you should be able to clean the throttle bodies at unauthorized workshops/by yourself without any issues. In case you do face the mentioned problems definitely take your car to the Toyota dealership.
Other cars with drive-by-wire (All Mercedes, BMW, Audi and Toyotas such as Mark X, Harrier etc)
Mercedes, Audi and BMW throttle bodies should only be serviced at authorized centers as they're using the same DBW technology (with a learning system).
And advanced Toyotas like Mark X, Harrier etc should totally avoid throttle body cleaning unless you're able to find a dealership which has the computerized programming procedure for these cars (highly unlikely).
The Rx-8 uses an electronic throttle which is unaffected by this problem. While it is a learning throttle system like the DBW, its learning process happens when the car's battery is unplugged. Rx-8 owners should clean their car's throttle body regularly as it is very susceptible to carbon buildup. This will keep your car running smoothly. Be sure to disconnect the battery when cleaning the throttle so that the ECU relearns the throttle system. Your car's RPM will be erratic for about 10 minutes of driving but it will become fine afterwards.
For DSC equipped Rx-8s: Be sure to do the DSC re-calibration procedure after unplugging your car's battery.
I hope this helps anyone who has faced this problem.