Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSSUBARU1990XT-6 4WD L6-2.7L SOHCREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTIGNITION SYSTEMSPARK PLUGTESTING AND INSPECTION
1990 Subaru XT-6 4WD L6-2.7L SOHC
Spark Plug: Testing and Inspection
1990 Subaru XT-6 4WD L6-2.7L SOHCSECTION Testing and Inspection
REMOVAL
1. Twist and pull to remove ignition wire from plug.
2. While wearing saftey glases, use compressed air to blow out debris from plug well.
3. Using a 5/8" (16mm) socket, remove plug.
CAUTION: Use care not to allow foreign matter to enter through plug holes.
INSPECTION
1. Check spark plugs for:
^ Broken insulator
^ Worn electrode
^ Carbon deposits
^ Damaged or broken gasket
^ Burnt condition of porcelain insulator at spark gap.
NOTE: Dark deposits indicate too rich a fuel mixture. Light (white) deposits indicate too lean a fuel mixture, advanced ignition timing or insufficient plug tightening
2. Check plug gap and adjust to 0.039 - 0.043in (1.0 - 1.1mm).
INSTALLATION
1. Adjust electrode gap to 0.039 - 0.043 in (1.0 - 1.1 mm).
2. Lightly coat threads of plug with anti-seize compound.
3. Install and thread plug into cylinder head by hand.
4. Torque spark plug to 14 - 22 ftlb (20 - 29 Nm).
5. Apply dielectric compound to the inside of ignition wire boot and install. A slight click will be heard when wire is properly connected.
6. Tighten spark plug to specified torque. Overtorqueing may damage cylinder head threads.
RECOMMENDED SPARK PLUGS
BRAND PART NO.
---------------------------------
NGK BPR6ES-11
NIPPONDENSO W20EPR-U11
CHAMPION RC9YC-4
1. Twist and pull to remove ignition wire from plug.
2. While wearing saftey glases, use compressed air to blow out debris from plug well.
3. Using a 5/8" (16mm) socket, remove plug.
CAUTION: Use care not to allow foreign matter to enter through plug holes.
INSPECTION
1. Check spark plugs for:
^ Broken insulator
^ Worn electrode
^ Carbon deposits
^ Damaged or broken gasket
^ Burnt condition of porcelain insulator at spark gap.
NOTE: Dark deposits indicate too rich a fuel mixture. Light (white) deposits indicate too lean a fuel mixture, advanced ignition timing or insufficient plug tightening
2. Check plug gap and adjust to 0.039 - 0.043in (1.0 - 1.1mm).
INSTALLATION
1. Adjust electrode gap to 0.039 - 0.043 in (1.0 - 1.1 mm).
2. Lightly coat threads of plug with anti-seize compound.
3. Install and thread plug into cylinder head by hand.
4. Torque spark plug to 14 - 22 ftlb (20 - 29 Nm).
5. Apply dielectric compound to the inside of ignition wire boot and install. A slight click will be heard when wire is properly connected.
6. Tighten spark plug to specified torque. Overtorqueing may damage cylinder head threads.
RECOMMENDED SPARK PLUGS
BRAND PART NO.
---------------------------------
NGK BPR6ES-11
NIPPONDENSO W20EPR-U11
CHAMPION RC9YC-4
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.