Troubleshooting - Toyota Supra 1990 Manual

ENGINE MECHANICAL - Troubleshooting EM-5
TROUBLESHOOTING (Cont'd)
Problem
Possible cause
Remedy
Page
Rough idle, stalls or
Spark plugs faulty
I nspect plugs IG-7
misses (cont'd)
Engine overheats
Check cooling system
CO-4
Low compression
Check compression
EM-20,21
Engine hesitates/ Vacuum leaks
Repair as necessary
poor acceleration
•
PCV hoses
•
EGR valve
•
Intake manifold
•
Air intake chamber
•
Throttle body
•
ISC valve
Pulling in air between air flow meter and
Repair as necessary
throttle body
Incorrect ignition timing
Reset timing IG-20
Emission control system problem
(cold engine)
•
EGR system always on
Check EG R system
EC-12,16
High-tension cord faulty
Inspect cord
IG-6, 11
Fuel system clogged
Check fuel system
FI-70
Air cleaner clogged
Check air cleaner
MA-5
E F I system problems
Repair as necessary
Spark plugs faulty
I nspect plugs IG-7
Engine overheats
Check cooling system
CO-4
Low compression
Check compression
EM-20,21
Engine diesels
E F I system problems
Repair as necessary
(runs after ignition
switch is turned off)
Muffler explosion
Deceleration fuel cut system always off
Check EFI (fuel cut) system
FI-124
(after fire) on deceleration
only
Muffler explosion Air cleaner clogged
Check air cleaner
MA-5
(after fire) all the time
EF I system problem
Repair as necessary
Incorrect ignition timing
Reset timing
IG-20
Engine backfires
Vacuum leak
Check hoses and repair as
•
PCV hoses
necessary
•
EGR valve
•
Intake manifold
•
Air intake chamber
•
Throttle body
•
ISC valve
Pulling in air between air flow meter and
Repair as necessary
throttle body
EFI system problem
Repair as necessary
I nsufficient fuel flow
Troubleshoot fuel system
Incorrect ignition timing Reset timing
IG-20
Carbon deposits in combustion chambers Inspect cylinder head EM-32