Engine Stalls At Idle - Before Warm-Up - Mazda MX-5 1990 Workshop Manual

F
TROUBLESHOOTING GUIDE
ENGINE STALLS AT IDLE - BEFORE WARM-UP
• Engine starts normally but vibrates excessively and stalls at idle before warm-up
[TROUBLESHOOTING HINTS]
CD
Low intake air amount
• Idle speed control malfunction
• Air cleaner element clogged
@
Air/Fuel mixture too lean
• Air leakage of intake air system
@
Poor atomization of fuel
• Airflow meter stuck
• Low RVP (summer) fuel used in cold weather
STEP
INSPECTION
1 Check if "00" is displayed on Self-Diagnosis
Checker with ignition switch ON
c:::r
page F-78
~~
.......
~
SYSTEM SELECT 1
-e--
TEST SW
\ SELF TEST
~1~n"l~ ~\
2 Check switches for correct operation with Self-
Diagnosis Checker Monitor Lamp with ignition
switch ON
c:r page F-89
SELECT SW A
3
Check if ECU terminal voltages are OK
(20, 20 and 2Q)
L7
page F-129
4
Check for correct intake manifold vacuum at idle
Vacuum: More than 450 mmHg (17.7 inHg)
F-44
No
No
ACTION
Go to next step
Malfunction Code No. displayed
Check for cause (Refer to specified
check sequence)
"88" flashes
Check ECU terminal 1 F voltage
Voltage; Approx. 12V
(Ignition switch ON)
c::> If OK, replace ECU
¢
If not OK, check wiring between
ECU and Self-Diagnosis Checker
Yes Go to next step
No Lamp not ON/OFF with specified
switch
Check for cause (Refer to specified
check sequence)
Lamp always ON
Check wiring between ECU terminal
1
D
c:::r page F-80
L7
page F-128
c:r page F-127
c:::r
page F-7
c:r page F-90
and Self-Diagnosis Checker
c:::r
page F-7
Yes Go to next step
No
Check for cause (Refer to "Check Point
for Each Terminal") c:::r
page F-132
Yes
Go to next step
No
Check for air leakage of intake air sys-
tem components
c:::r
page F-93
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