1A-9 Engine General Information and Diagnosis:
Engine runs poorly in
high speed range
(Defective engine internal/
electrical parts)
Weakened valve springs. Replace.
Worn camshaft. Replace.
Valve timing out of adjustment. Adjust.
Incorrect spark plug gap. Replace.
Ignition not advanced sufficiently due to
poorly working timing advance circuit.
Replace ECM.
Defective ignition coil. Replace.
Defective CKP sensor. Replace.
Defective ECM. Replace.
Clogged air cleaner element. Clean.
Clogged fuel feed hose or fuel delivery
pipe, resulting in inadequate fuel supply
to injector.
Clean and prime.
Defective fuel pump. Replace.
Defective TP sensor. Replace.
Engine runs poorly in
high speed range
(Defective air flow
system)
Clogged air cleaner element. Clean or replace.
Defective throttle valve. Adjust or replace.
Sucking air from throttle body or intake
pipe joint.
Repair or replace.
Defective ECM. Replace.
Engine runs poorly in
high speed range
(Defective control circuit
or sensor)
Low fuel pressure. Repair or replace.
Defective TP sensor. Replace.
Defective IAT sensors. Replace.
Defective IAP sensor. Replace.
Defective CKP sensor. Replace.
Defective ECM. Replace.
Defective GP sensor. Replace.
TP sensor out of adjustment. Adjust.
Engine lacks power
(Defective engine internal/
electrical parts)
Loss of valve clearance. Adjust.
Weakened valve springs. Replace.
Valve timing out of adjustment. Adjust.
Worn piston rings or cylinder. Replace.
Poor seating of valves. Repair.
Fouled spark plug. Clean or replace.
Incorrect spark plug. Adjust or replace.
Clogged fuel injector. Clean.
TP sensor out of adjustment. Adjust.
Clogged air cleaner element. Clean.
Sucking air from throttle body or intake
pipe joint.
Retighten or replace.
Too much engine oil. Drain out excess oil.
Defective fuel pump or ECM. Replace.
Defective CKP sensor and ignition coil. Replace.
Engine lacks power
(Defective control circuit
or sensor)
Low fuel pressure. Repair or replace.
Defective TP sensor. Replace.
Defective IAT sensor. Replace.
Defective CKP sensor. Replace.
Defective IAP sensor. Replace.
Defective GP sensor. Replace.
Defective ECM. Replace.
TP sensor out of adjustment.
Adjust.
Engine ov
erheats
(Defective engine internal
parts)
Heavy carbon deposit on piston crown. Clean.
Not enough oil in the engine. Add oil.
Defective oil pump or clogged oil circuit. Replace or clean.
Use of incorrect engine oil. Change.
Sucking air from throttle body or intake
pipe joint.
Retighten or replace.
Defective cooling system. Refer to “Engine Cooling Symptom Diagnosis”
in Section 1F (Page 1F-3).
Condition Possible cause Correction / Reference Item
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