Mazda MX-5 1990 Workshop Manual page 171

TROUBLESHOOTING GUIDE
F
STEP
5
INSPECTION
Check if ECU terminal voltages are OK
(20, 20 and 20)
ACTION
Yes Go to next step
c::::r
page F-129 No Check for cause (Refer to "Check Point
6
Check if strong blue spark is visible at each dis-
connected high-tension lead while cranking
engine
7
for Each Terminal")
0 '
page
F-132
Yes Go to next step
No Check ignition systeLP (Refer to Trouble-
shooting "Misfire")
L7'
page G--18
Yes Go to Step
9
No Go to Step 8
8 Check if approx. 12V exists at injector connector Yes Check if injector resistance is OK
(W/R) wire with ignition switch ON
0 '
page
F-112
9 Check for correct engine compression
c::::r
page
9-10
Engine compression: 1,324-932 kPa
(13.5-9.5 kg/cm
2
,
192-135 psi) . 300 rpm
10
Check
if
spark plugs are
OK
WEAR AND CARBON BUILDUP
PLUG GAP
1.0-1.1mm
(0.039-0.043 in)
'rrN""-= ____
BURNS
~~hDAMAGE
AND
DETERIORATION
DAMAGE
11 Try known good ECU and check if condition
improves
0 '
page F-127
No
Yes
Resistance: Approx. 140
9
If OK, check wiring between injec-
tor and ECU
¢
If not OK, replace injector
Check wiring between main relay and
injector
Go to next step
L7'
page F-7
c::::r
page
F-112
c::::r
page F-7
No Check engine condition
L7'
page B-10
- Worn piston, piston rings or cylinder
wall
• Defective cylinder head gasket
• Distorted cylinder head
-Improper valve seating
- Valve sticking in guide
Yes Go to next step
No Repair, clean, or replace
CT
page G-20
05UOFX-022
F-27