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2008 - MX-5 - Transmission/Transaxle

NO.14 ENGINE FLARES UP OR SLIPS WHEN UPSHIFTING OR DOWNSHIFTING [SJ6A-EL]



14

Engine flares up or slips when upshifting or downshifting

DESCRIPTION

  • When the accelerator pedal is depressed for acceleration from standstill, engine speed increases but the vehicle speed increases slowly.

  • When the accelerator pedal is depressed while driving, engine speed increases but the vehicle speed does not.

POSSIBLE CAUSE

  • There is clutch slippage because the clutch is stuck or the line pressure is low.

    • Clutch stuck, slippage (C1 clutch, C2 clutch, C3 clutch, B1 brake, B2 brake, B3 brake)

      • Line pressure low

      • Incorrect throttle position signal

      • Incorrect accelerator pedal position signal

      • Incorrect engine speed signal

      • Incorrect engine coolant temperature signal

      • Incorrect engine torque signal

      • VSS malfunction

      • Turbine sensor malfunction

      • Sensor GND malfunction

      • Shift solenoid A malfunction

      • Shift solenoid B malfunction

      • Shift solenoid C malfunction

      • Shift solenoid D malfunction

      • Shift solenoid E malfunction

      • Line pressure control solenoid malfunction

      • TCC control solenoid malfunction

      • Shift solenoid F malfunction

      • Shift solenoid G malfunction

      • Body GND malfunction

      • Control valve body malfunction

NOTE:

  • Before following the troubleshooting steps, make sure that the Automatic Transmission On-Board Diagnostic and Automatic Transmission Basic Inspection are conducted. (See BASIC INSPECTION [SJ6A-EL].)


Diagnostic procedure

STEP

INSPECTION

ACTION

1

Yes

Go to the next step.

No

Repair or replace any malfunctioning parts according to the inspection results.

2

Yes

Go to the next step.

No

Go to No.9 “ABNORMAL SHIFTING”.

3

  • Access the following PCM PIDs using the M-MDS.

    • RPM

    • APP

    • TP

    • ECT

    • ENG_TRQ

  • Are PIDs value normal?

Yes

Go to the next step.

No

Inspect and repair suspected PID related part.

4

  • Stop the engine.

  • Inspect following solenoids.

    (See SOLENOID VALVE INSPECTION [SJ6A-EL].)

    • Shift solenoid A

    • Shift solenoid B

    • Shift solenoid C

    • Shift solenoid D

    • Shift solenoid E

    • Line pressure control solenoid

    • TCC control solenoid

    • Shift solenoid F

    • Shift solenoid G

  • Are they normal?

Yes

Inspect the ATF condition.

No

Replace the control valve body.

(See CONTROL VALVE BODY REMOVAL [SJ6A-EL].)

(See CONTROL VALVE BODY INSTALLATION [SJ6A-EL].)

5

  • Inspect the coupler component for open or short.

  • Are coupler component normal?

Yes

Go to the next step.

No

Replace the coupler component.

6

  • Inspect the ATF condition.

  • Are a large amount of specks found?

Yes

Replace the transmission.

(See AUTOMATIC TRANSMISSION REMOVAL/INSTALLATION [SJ6A-EL].)

No

Replace the control valve body.

(See CONTROL VALVE BODY REMOVAL [SJ6A-EL].)

(See CONTROL VALVE BODY INSTALLATION [SJ6A-EL].)

7

  • Verify test results.

    • If normal, return to the diagnostic index to service any additional symptoms.

    • If malfunction remains, inspect the related Service Bulletins and/or On-line Repair Information and perform repair or diagnosis.

      • If the vehicle is repaired, troubleshooting completed.

      • If the vehicle is not repaired or additional diagnostic information is not available, replace the TCM.




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