Base Engine Misfire Without Internal Engine Noises - Suzuki XL7 2007 Service Manual

Base Engine Misfire without Internal Engine Noises

Abnormalities, severe cracking, bumps, or missing areas,
in the accessory drive belt
Abnormalities in the accessory drive system and/or
components may cause engine RPM variations and lead
to a misfire DTC. A misfire code may be present without
an actual misfire condition.
Worn, damaged, or mis-aligned accessory drive
components or excessive pulley runout and may lead to a
misfire DTC.
A misfire code may be present without an actual misfire
condition.
Loose or improperly installed engine flywheel or
crankshaft balancer
A misfire code may be present without an actual misfire
condition.
Restricted exhaust system
A severe restriction in the exhaust flow can cause
significant loss of engine performance and may set a
DTC. Possible causes of restrictions include collapsed or
dented pipes or plugged mufflers and/or catalytic
converters.
Improperly installed or damaged vacuum hoses
Improper sealing between the intake manifold and
cylinder heads, intake manifold and plenum duct, plenum
duct and water crossover, water crossover and throttle
body and/or pressure relief valve and intake manifold.
Improperly installed or damaged MAP sensor and/or seal
The sealing grommet of the MAP sensor should not be
torn or damaged.
Improperly installed or damaged EVAP purge solenoid
and/or O-ring seal
Worn or loose followers, valve rocker arms
The follower, valve rocker arm, roller bearing should be
intact and in the proper position
Stuck valves
Carbon buildup on the valve stem can cause the valve not
to close properly.
Excessively worn or mis-aligned timing chain or chains
Worn camshaft lobes
Excessive oil pressure
A lubrication system with excessive oil pressure may lead
to excessive valve lifter pump-up and loss of
compression.
Faulty cylinder head gaskets and/or cracking or other
damage to the cylinder heads and engine block cooling
system passages. Refer to "Diagnostic Starting Point -
Vehicle Diagnostic Information: ".
Coolant consumption may or may not cause the engine to
overheat.
Cause Correction
Replace the drive belt. Refer to "Drive Belt Replacement".
Inspect the components, repair or replace as required.
Repair or replace the flywheel and/or balancer as
required. Refer to "Engine Flywheel Replacement" or
"Crankshaft Balancer Replacement".
Repair or replace as required.
Repair or replace as required.
Replace the intake manifold, plenum duct, gaskets,
cylinder heads, throttle body and/or pressure relief valve
as required.
Repair or replace the MAP sensor as required.
Repair or replace the EVAP purge solenoid as required.
Replace the followers, valve rocker arms, as required.
Repair or replace as required.
Replace the timing chain or chains and sprockets as
required.
Replace the camshaft or camshafts and SHLAs, valve
lifters.
• Perform an oil pressure test. Refer to "Oil Pressure
Diagnosis and Testing: ".
• Repair or replace the oil pump as required.
• Inspect for spark plugs saturated by coolant. Refer to
"Spark Plug Inspection: " for the 3.6L engine.
• Inspect the cylinder heads, engine block, and/or head
gaskets.
• Repair or replace as required.
Engine Mechanical: 1D-27