Mazda MX-5 1990 Workshop Manual page 202

F
TROUBLESHOOTING GUIDE
STEP
INSPECTION
9 Check for correct engine compression
c::::r
page
8-10
Engine compression: 1,324-932 kPa
(13.5-9.5 kg/cm
2
,
192-135 psi) - 300 rpm
ACTION
Yes Go to next step
No Check engine condition c:::r page B-10
- Worn piston, piston rings or cylinder
wall
- Defective cylinder head gasket
• Distorted cyli nder head
-Improper valve seating
• Valve sticking in guide
10 Check for correct intake manifold vacuum at idle Yes Go to next step
Intake manifold vacuum:
More than 450 mmHg (17.7 inHg)
11 Check if air cleaner element is clean
c:::r page F-75
12
Check for injector operating sound at idle
13 Check if approx. 12V exists at injector connector
(W/R) wire with ignition switch ON
14 Check if ECU terminal voltages are OK
(20, 20 and 20)
No Check for air leakage of intake air sys-
tem components c:::r page F-93
Yes Go to next step
No Replace air cleaner element
L7
page
F-92
Yes Go to Step 14
No Go to Step 13
Yes Check if injector resistance is OK
c:::r page F-99
Resistance: Approx. 140
¢
If OK, check wiring between ECU
and injector c:::r page F-7
c:>
If not OK, check injector for fuel
leakage
L7
page
F-113
No Check wiring between ECU and injector
c:::T
page F-7
Yes Go to next step'
c:::r page F-129
No Check for cause (Refer to "Check Point
for Each Terminal")
c::r
page
F-132
F-58