Instant drop in RPM

[Evholic_7]

Hello everyone! I really need your help because I hear an engine knock sound when I rev it in neutral, and the RPM drop is instantly and I don't understand why. The car is about 40k miles. Any thoughts or suggestions? Please don't send me to the dealership because I have already been there five times.

 

[SuzukiDriver2024]

At 40k miles, the RPMs shouldn't drop sharply but rather cushion at around 1000 and then settle at 750. When you were at the dealership, did they mention anything about the fuel injection system?

If they didn’t, it might be worth asking them to monitor the fuel injection parameters more closely. If they can’t find anything, it might be time to get a second opinion from a trusted independent mechanic who can dig deeper.