Mazda MX-6 1998, Workshop Manual

Page: 123 / 1282

TROUBLESHOOTING [ENGINE CONTROL FS]
DTC P1121 TP sensor input signal inconsistent with MAF sensor
DESCRIPTION
• Continuous Memory DTC P1121 indicates throttle position is inconsistent with MAF sensor
[Possible Cause]
• Damaged TP sensor • Air leak between MAF sensor and throttle body
• TP sensor not seated properly (almost completely
detached from throttle body)
STEP INSPECTION
ACTION
1 TP SENSOR AND MAF SENSOR
RATIONALITY CHECK
• Attempt to start engine.
• Does engine run?
Yes
Go to next step.
No CHECK for major leaks, cracks, and openings between
MAF sensor and throttle body.
2
CHECK MECHANICAL OPERATION OF TP
SENSOR
• Key on, engine off.
• Access TP V PID with the NGS tester.
• Slowly move throttle from closed throttle
position to wide open throttle position and
observe TP V PID for smooth reading
change.
• While opening and closing the throttle,
is there a sudden drop In TP V PID
below 0.66 volts or sudden jump in TP V
PID above 1.20 volts?
Yes
TP sensor has internal substrate problem.
REPLACE TP sensor.
RERUN OBD Test.
No Go to next step.
3 CHECK TP SENSOR SIGNAL HIGH
VERSUS THE ENGINE LOAD WHILE
DRIVING VEHICLE
• Key on, engine running.
• Do normal drive, exercising throttle and TP
sensor while accessing PIDs.
• Access TP V PID and LOAD PID with NGS
tester and record readings.
• Is TP V PID greater than 2.44 volts and
LOAD PID reading less than 25%?
Yes CHECK for air leaks between the MAF sensor and throttle
body including air noise sounds while engine is running.
SERVICE as necessary.
If okay, REPLACE TP sensor.
RERUN OBD Test.
No Go to next step.
4 CHECK TP SENSOR SIGNAL LOW VERSUS
THE ENGINE LOAD
• Key on, engine running.
Note
• If the vehicle does not start, go to ENGINE
SYMPTOM TROUBLESHOOTING.
• Access TP V PID and LOAD PID with NGS
tester and record readings.
• Is TP V PID reading less than 0.24 volts
and LOAD PID reading greater than
60%?
Yes CHECK for TP sensor loosely connected to throttle body
(screws not securely tightened down).
SERVICE as necessary.
RESET PCM to completely clear DTCs.
tr After Repair Procedure
COMPLETE OBD II Drive Mode.
DRIVE vehicle exercising throttle.
RERUN OBD Test.
If Continuous Memory P1121 is present, REPLACE MAF
sensor.
No Go to next step.
5
CHECK TP SENSOR SIGNAL LOW VERSUS
THE ENGINE LOAD WHILE DRIVING
VEHICLE
• Key on, engine running.
• Do normal drive, exercising throttle and TP
sensor near higher gears (preferably
overdrive) while accessing PIDs.
• Access TP V PID and LOAD PID with NGS
tester and record readings.
• Is TP V PID reading less than 0.24 volts
and LOAD PID reading greater than
60%?
Yes CHECK for TP sensor loosely connected to the throttle
body (screws not securely tightened down).
SERVICE as necessary.
RESET PCM to completely clear DTCs.
tr After Repair Procedure
COMPLETE OBD II Drive Mode.
DRIVE vehicle exercising the throttle.
RERUN OBD Test.
If Continuous Memory P1121 is now present, REPLACE
MAF sensor.
No Unable to identify fault at this time. If vehicle does not
start, go to ENGINE SYMPTOM TROUBLESHOOTING.
01-01A -95