Possible reasons for floating speed after replacing an automatic transmission:
* Incorrect accelerator cable adjustment: Adjust the accelerator cable so that the throttle valve opens and closes smoothly.
* Air leaks: Check for air leaks in the intake system, especially connections, hoses and gaskets.
*Throttle Position Sensor (TPS) Problem: Replace the faulty TPS as this may result in incorrect throttle position readings.
*Mass Air Flow Sensor (MAF) Problem: Replace the faulty MAF as this may cause the air/fuel mixture to be miscalculated.
* Crankshaft Position (CKP) sensor problem: Replace the faulty CKP as it provides information about engine speed and piston position.
*Engine control unit (ECU) problem: Reprogram or replace the ECU as it may contain incorrect programming or be damaged.
* Mechanical Problem: Check for mechanical problems such as worn piston rings or valves that could cause loss of compression and rough operation.
Troubleshooting steps:
1. Read trouble codes using a diagnostic scanner to identify possible problems.
2. Check and adjust the accelerator cable.
3. Check for air leaks in the intake system.
4. Check the TPS and replace it if necessary.
5. Check the MAF and replace it if necessary.
6. Check the CKP and replace it if necessary.
7. Reprogram or replace the ECU if necessary.
8. Check for mechanical problems and repair if necessary.