Base Engine Misfire With Abnormal Internal Lower Engine Noises - Suzuki XL7 2007 Service Manual

1D-28 Engine Mechanical:
Worn Piston Rings
Oil consumption may or may not cause the engine to
misfire.
A damaged crankshaft reluctor wheel
A damaged crankshaft reluctor wheel can result in
different symptoms depending on the severity and
location of the damage.
• Systems with SEVERE reluctor ring damage may
exhibit periodic loss of crankshaft position, stop
delivering a signal, and then re-sync the crankshaft
position.
• Systems with SLIGHT reluctor ring damage may exhibit
no loss of crankshaft position and no misfire may occur.
However, a P0300 DTC may be set.

Base Engine Misfire with Abnormal Internal Lower 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, noises
similar to a faulty lower engine and also lead to a misfire
condition. A misfire code may be present without an
actual misfire condition.
Worn, damaged, or mis-aligned accessory drive
components or excessive pulley runout
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.
Worn or Broken Piston Rings
Oil consumption may or may not cause the engine to
misfire.
Worn Crankshaft Thrust Bearings
Severely worn thrust surfaces on the crankshaft and/or
thrust bearing may permit fore and aft movement of the
crankshaft and create a DTC without an actual misfire
condition.
Cause
Cause
Correction
• Inspect the spark plugs for oil deposits. Refer to "Spark
Plug Inspection: " for the 3.6L engine.
• Inspect the cylinders for a loss of compression. Refer
to "Engine Compression Test".
• Perform cylinder leak down and compression testing to
identify the cause.
• Repair or replace as required.
Replace the crankshaft as required.
Correction
Replace the drive belt. Refer to "Drive Belt Replacement".
Inspect the components, repair or replace as required.
Repair or replace the engine flywheel and/or crankshaft
balancer as required.
Refer to "Engine Flywheel Replacement" or "Crankshaft
Balancer Replacement".
• Inspect the spark plugs for oil deposits. Refer to "Spark
Plug Inspection: " for the 3.6L engine.
• Inspect the cylinders for a loss of compression. Refer
to "Engine Compression Test".
• Perform cylinder leak down and compression testing to
determine the cause.
• Repair or replace as required.
Replace the crankshaft and bearings as required.