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Home >> Mazda >> 2024 >> CX-90 Turbo Select >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 1 (Symptom Troubleshooting - Engine (VIN A)) >> Fast Idle/Runs On [PYUL] >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different variant/trim than selected.
FAST IDLE/RUNS ON (PYUL) DIAGNOSTIC PROCEDURE

Step Inspection Results Action
1 VERIFY COOLING SYSTEM OPERATION FOR MALFUNCTION 
  • Access the PCM PID [ECT] using the M-MDS. (See PID/DATA MONITOR INSPECTION .)
  • Start the engine and warm it up completely.
  • Is the PID value between 82-112°C {180-234°F}?
Yes Go to the next step.
No ECT PID value is higher than 112°C {234°F}: 
ECT PID value is less than 82°C {180°F}: 
2 VERIFY PCM DTCs 
  • Perform the DTC inspection for the PCM. (See DTC INSPECTION .)
  • Are any DTCs displayed?
Yes Repair or replace the malfunctioning location according to the applicable DTC troubleshooting.
(See DTC TABLE [PCM (PYUL)] .)
No Go to the next step.
3 VERIFY CURRENT INPUT SIGNAL STATUS 
WARNING:
  • Observe legal speed limits when driving the vehicle and perform the procedure in a location where safety can be assured. 
  • To prevent an accident, work with two people when the vehicle is being driven (one person drives vehicle, other person operates M-MDS). 
Yes Go to the next step.
No APP1, APP2 PIDs are not as specified: 
ECT, ECT_VOLT PIDs are not as specified: 
A/F_SEN_CUR, SHRT_FUEL_TRIM, LONG_FUEL_TRIM PIDs are not as specified: 
HO2S_OUT_VOLT PID is not as specified: 
  • Inspect the HO2S. (Refer to [HEATED OXYGEN SENSOR (HO2S) INSPECTION ] in Service Information). Repair or replace the malfunctioning location.
    • If the malfunction remains:
      • Inspect communication error between TCM and PCM.
        • Repair or replace the malfunctioning location and perform the repair completion verification 1.
      • Perform the [Action for Non-repeatable Malfunction] procedure.

        (See TROUBLESHOOTING PROCEDURE .)

4 DETERMINE IF MALFUNCTION CAUSE IS A/C REQUEST SIGNAL OR OTHER 
  • Access the PCM [A/C_REQ] PID using the M-MDS. (See PID/DATA MONITOR INSPECTION .)
  • Monitor the A/C_REQ PID while turning on and off the air conditioner using the switch on the control panel.
  • Does the A/C_REQ PID value change from Yes to No according to switch control panel?
Yes Go to the next step.
No If the A/C_REQ PID is always Yes:
  • Perform the symptom troubleshooting [A/C IS ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY].

If the A/C_REQ PID is always No:
  • Perform the symptom troubleshooting [A/C DOES NOT WORK SUFFICIENTLY].
5 DETERMINE IF MALFUNCTION CAUSE IS DRIVE-BY-WIRE CONTROL SYSTEM OR OTHER 
  • Will the engine run smoothly at part throttle?
Yes Go to Step 7.
No Go to the next step.
6 INSPECT DRIVE-BY-WIRE CONTROL SYSTEM OPERATION  Yes Visually inspect the throttle body (damage/scratching).
  • If there is any malfunction:
    • Repair or replace the malfunctioning location and perform the repair completion verification 1.
  • If there is no malfunction:
    • Go to the next step.
No Repair or replace the malfunctioning location and perform the repair completion verification 1.
7 INSPECT FUEL INJECTOR OPERATION 
  • Perform [Fuel Injector Operation Inspection]. (Refer to [FUEL INJECTOR INSPECTION ] in Service Information).
  • Do the fuel injectors operate properly?
Yes Go to the next step.
No Repair or replace the malfunctioning location and perform the repair completion verification 1.
8 INSPECT HIGH PRESSURE FUEL PUMP  Yes Go to the next step.
No Repair or replace the malfunctioning location and perform the repair completion verification 1.
(Refer to [HIGH PRESSURE FUEL PUMP REMOVAL/INSTALLATION ] in Service Information).
9 INSPECT INTAKE-AIR SYSTEM FOR AIR LEAKAGE 
  • Inspect for leakage in intake-air system.
  • Is there any leakage?
Yes Repair or replace the malfunctioning location and perform the repair completion verification 1.
No Injector driver malfunction.
If the problem remains, overhaul the engine and perform the repair completion verification 1.
Repair completion verification 1 VERIFY THAT VEHICLE IS REPAIRED 
  • Install/connect the part removed/disconnected during the troubleshooting procedure.
  • Has the malfunction symptom been eliminated?
Yes Complete the symptom troubleshooting. (Explain contents of repair to customer)
No Refer to the controller area network (CAN) malfunction diagnosis flow to inspect for a CAN communication error.
(See MALFUNCTION DIAGNOSIS FLOW [CONTROLLER AREA NETWORK (CAN)] .)
  • If the CAN communication is normal, perform the diagnosis from Step 1.