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.

1991 Ford Bronco 4.9 Y, Standard, M5OD-R2FACTORY OEM SERVICE PROCEDURE

Spark Plug Specifications

SPARK PLUG SPECIFICATIONS

Application

Motorcraft No.

⁽¹⁾ Plug Gap

5.0L

ASF-42C

See Emissions Decal

5.8L

ASF-32C

See Emissions Decal

7.5L

ASF-44P

See Emissions Decal

⁽¹⁾	For the most current information, always refer to the Emissions Decal in the engine compartment.

Factory Service Tools

Use the Manual With the Right Hardware

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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.