After Elantra washed the throttle, sometimes the speed reached 1500 at the start, and then it was normal to stop. What happened?

Idle instability is not only a problem of throttle, but also an idle valve. It is not enough to clean only the throttle valve, but also the idle valve. After adding fuel additives, it needs to run at a speed of about 3000 rpm for one hour immediately to play a cleaning role. If the engine is still running at a low speed after adding the cleaning agent, the cleaning agent is equal to adding it in vain (invalid). If you are not satisfied with the results, you can go to a professional repair shop to do a computer reprogramming (free of charge during the warranty period), that is, rewrite the program and delete your driving habits from the previous computer memory.