Possible reasons for a drop in engine speed when changing gears in an automatic transmission:
1. Low transmission fluid level:
* Insufficient fluid level can lead to gear slipping and a drop in speed.
2. Worn or faulty transmission:
* Ringing gears, slow shifting and vibration may indicate wear or problems in the transmission.
3. Problems with sensors:
* A faulty input or output shaft speed sensor may provide incorrect information about engine speed, causing RPM to drop.
4. Faulty throttle valve:
* The throttle valve is responsible for controlling the air supply to the engine. If it is faulty, it can lead to a drop in engine speed.
5. Problems with electronics:
* Problems with the electronic control unit (ECU) or wiring may interfere with signal transmission between the engine and transmission.
6. Worn spark plugs or coils:
* Worn spark plugs or faulty coils can cause misfire, which can lead to a drop in engine speed.
7. Clogged fuel injectors:
* Clogged injectors can prevent fuel from being delivered to the engine, resulting in loss of power and reduced rpm.
8. Air filter dirty:
* A dirty air filter can restrict air flow to the engine, resulting in loss of power.
9. Problems with the exhaust system:
* A clogged catalytic converter or muffler can create back pressure, reducing engine power and rpm.
10. Worn or faulty drive belt:
* A worn or faulty drive belt can slip, causing a loss of power and a drop in engine speed.