Ford Mustang GT engine backfiring issue with cam replacement and emissions light on on Ford Transit Connect

Some Ford Mustang GT owners report experiencing engine backfiring issues, particularly after a cam replacement and with the emissions light illuminated. These problems may stem from improper engine timing, bad spark plugs, or faulty plug wires, which can lead to a rich fuel mixture. Additionally, the emissions light could signal a malfunctioning camshaft phaser that may be stuck open, triggering diagnostic codes. Owners also note that backfiring combined with a check engine light may indicate a camshaft position sensor issue, resulting in sluggish performance and reduced gas mileage. If the engine backfires and spits through the carburetor following a rebuild, it could be linked to timing chain problems, cam setup errors, or incorrect firing order. It is crucial for owners to check the cam timing setup, as a jumped tooth in the timing chain can lead to sudden backfiring. To accurately determine the compression stroke, some owners suggest using a towel in the spark plug hole while turning the engine over to find the correct position. Addressing these factors is vital for effectively diagnosing and resolving the backfiring issue.