Ask why the car will avoid unstable speed after washing the throttle, and there will be some slight shaking, high-speed avoidance and loud noise after engine maintenance.

The problem is not big. Don't worry. You can solve the problem by checking two aspects:

1, because the car has not been maintained for a long time, there is a lot of carbon deposit, and it failed to clean the dirt once. These carbon deposits will get stuck on valves, valve seats, fuel injectors and other parts, which will affect the work of those parts and lead to similar phenomena. Solution: continue to increase the amount of carbon and colloid deposited in the fuel system to ensure that the dirt is thoroughly cleaned;

2. After cleaning, use the computer to read the ECU data stream, and focus on checking the throttle sensor, crankshaft sensor, air flowmeter, idle speed and other information. Adjust the data flow and troubleshoot.

On the whole, the problem is not big. It is feasible to choose the maintenance method, but unfortunately the maintenance items are incomplete and unprofessional. You've played a lot. Following the above steps will definitely solve the problem. I hope I can help you.