Possible reasons for speed jumping when shifting automatic transmission gears:
1. Low transmission fluid level:
* Check the transmission fluid level. A low level can cause insufficient pressure, which leads to delayed gear shifts and jumping revs.
2. Faulty transmission filter:
*A dirty or clogged transmission filter can restrict transmission fluid flow, causing similar problems.
3. Worn friction discs:
* Friction discs in automatic transmissions wear out over time, which leads to their slipping and increased speed when changing gears.
4. Faulty shift solenoid:
* Shift solenoids are responsible for controlling the flow of transmission fluid into the automatic transmission. A faulty solenoid can cause rough shifting and rpm fluctuations.
5. Worn seals:
* Worn seals can allow transmission fluid to leak, leading to low pressure and shifting problems.
6. Faulty automatic transmission ECU:
* The automatic transmission electronic control unit (ECU) controls all automatic transmission functions. A faulty ECU can lead to system malfunctions and speed jumps.
7. Torque converter problem:
* The torque converter transfers torque from the engine to the transmission. A faulty torque converter can cause the revs to jump when changing gears.
Solution:
* Check the transmission fluid level and add if necessary.
* Replace the transmission filter.
* Diagnose and replace worn friction discs.
* Diagnose and replace faulty shift solenoids.
* Inspect and replace worn seals.
* Scan the automatic transmission ECU for faults.
* Inspect and repair or replace the faulty torque converter.
If the problem persists, contact a qualified transmission mechanic for further diagnosis and repair.