TOYOTA PREVIA 91-97 REPAIR MANUAL

3-80 ENGINEAND ENGINE OVERHAUL

Troubleshooting Engine Performance

Problem

Power not up to normal

Intake backfire

Exhaust backfire

Ping or spark knock

^^J Cause

(cont.) • Incorrect

• Faulty fue
  
  
  • Faulty fue
  
  
  • Incorrect
  
  
  • Faulty ign
  
  
  • Faulty ign
  
  
  • Improper
  
  
  • Blown cy
  
  
  • Leaking p
  
  
  • Improper
    operatic
  
  
  • Improper
  
  
  • Defective
  
  
  • Defective
    valve
  
  
  
  


• Air leak ir
  
  
  • Faulty air
  
  
  • Exhaust
  
  
  
  


• Incorrect
  
  
  • Distribute
  
  
  • Excessivi
    deposit;
  
  
  
  


• Air leak it
  
  
  • Excessivi
  
  
  
  


• Fuel octa
  
  
  • Sharp ed
    chambe
  
  
  
  


• EGR vaK
  properly

Surging (at cruising to top speeds) • Low fuel

volume

• Improper


• Air leak i 1


• Incorrect


• Restricte:


• Restricte:

park plug gap

pump

pump

alve timing

tion coil

tion wires

' seated valves

nder head gasket

ston rings

eedback system

i

gnition timing

EGR component

TAG vacuum motor or

to manifold vacuum

injection diverter valve

;ak

gnition timing

• advance malfunction

combustion chamber

to manifold vacuum

iy high compression

e rating excessively low

es in combustion

e not functioning

ump pressure or

3 CV valve air flow

to manifold vacuum

park advance

fuel filter

air cleaner

• EGR valfs not functioning
  properly


• Improper feedback system
  operation

Solution

• Adjust gap


• Replace fuel pump


• Replace fuel pump


• Check valve timing and repair as
  necessary


• Test coil and replace as necessary


• Test wires and replace as
  necessary


• Test cylinder compression and
  repair as necessary


• Replace gasket


• Test compression and repair as
  necessary


• Refer to Chapter 4


• Adjust timing


• Repair as necessary


• Repair as necessary


• Check manifold vacuum and repair
  as necessary


• Test diverter valve and replace as
  necessary


• Locate and eliminate leak


• Adjust timing


• Inspect advance mechanism and
  repair as necessary (Distributor
  systems only)


• Remove with combustion chamber
  cleaner


• Check manifold vacuum and repair
  as necessary


• Test compression and repair as
  necessary


• Try alternate fuel source


• Grind smooth


• Test EGR system and replace as
  necessary


• Replace fuel pump


• Test PCV valve and replace as
  necessary


• Check manifold vacuum and repair
  as necessary


• Test and replace as necessary


• Replace fuel filter


• Clean or replace air cleaner filter
  element


• Test EGR system and replace as
  necessary


• Refer to Chapter 4

TCCS3C07