1.Vacuum Leak:
- A vacuum leak can cause this problem. When you apply the brakes, it creates a vacuum in the intake manifold, which can cause the engine to run lean and the RPMs to drop.
- Check for any loose or cracked hoses in the intake system, and make sure the throttle body and intake manifold are properly sealed.
2.Idle Air Control (IAC) Valve:
- The IAC valve controls the amount of air that flows into the engine at idle. If the IAC valve is sticking or dirty, it can cause the RPMs to drop and the engine to run rough.
- Clean the IAC and check its operation.
3. Throttle Position Sensor (TPS):
- The TPS sends a signal to the engine's computer about the position of the throttle. If the TPS is faulty, it can send the wrong signal to the computer causing it to adjust the fuel and air mixture incorrectly, resulting in a drop in RPM.
- Check the TPS and its wiring for any damage or malfunction.
4. Faulty Brake Booster:
- In case of a faulty brake booster, when the brake pedal is applied, it may cause a vacuum leak in the brake booster line. This vacuum leak can affect the engine's idle stability, leading to a drop in RPM.
- Check the brake booster and its vacuum line for any leaks or damages.
5. Fuel Pressure:
- Insufficient fuel pressure can also cause this issue. When the brakes are applied, the fuel pump may not be able to provide enough fuel to the engine, resulting in a drop in RPM.
- Check the fuel pressure and ensure it meets the manufacturer's specifications.
