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2021
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Rough Idle or Engine Misfire

Expert diagnosis and repair solutions for 2021 Ford F-150 Rough Idle or Engine Misfire. Get step-by-step fixes, cost estimates, and professional advice.

Expert Repair Solutions

1
medium$50-$100
Replace the spark plugs with Ford Performance spark plugs to resolve rough idle and misfire issues.
Source: https://www.f150ecoboost.net/threads/rough-idle-no-computer-codes.89662/

Repair Steps:

  1. Purchase Ford Performance spark plugs.
  2. Remove the engine cover to access the spark plugs.
  3. Use a spark plug socket to remove the old spark plugs.
  4. Install the new spark plugs, ensuring proper gap.
  5. Reinstall the engine cover.
2
mediumFree under warranty
Perform a PCM software update to address misfire-related DTCs such as P0300 and P0304.
Source: https://static.nhtsa.gov/odi/tsbs/2021/MC-10169890-0001.pdf

Repair Steps:

  1. Schedule an appointment with a Ford dealer.
  2. Request a PCM software update as per TSB 21-2158.
  3. Dealer performs the update and resets the keep alive memory (KAM).
  4. Test drive the vehicle to ensure the issue is resolved.
3
hard$100-$300
Inspect and repair any vacuum leaks that may be causing rough idle.
Source: https://repairpal.com/ford/f-150/2021/rough-idle

Repair Steps:

  1. Visually inspect vacuum hoses for cracks or disconnections.
  2. Use a smoke machine to identify leaks in the intake system.
  3. Replace or repair any damaged vacuum hoses.
  4. Recheck for leaks and ensure proper engine idle.
4
medium$150-$300
Replace ignition coils if misfire persists after spark plug replacement.
Source: https://www.f150forum.com/f118/rough-idle-no-codes-showing-507603/

Repair Steps:

  1. Purchase new ignition coils compatible with the 2021 F-150.
  2. Remove the engine cover to access the ignition coils.
  3. Disconnect the electrical connectors from the coils.
  4. Remove the old coils and install the new ones.
  5. Reconnect the electrical connectors and reinstall the engine cover.

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