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Light Throttle Misfire - Solved

2004 - 2008 F-150

Light Throttle Misfire - Solved

Old 04-07-2019, 08:00 PM
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Light Throttle Misfire - Solved

Hi guys,

I'm new to the forum, I have gained a lot from reading threads on here and thought I'd contribute my part. For the last 50,000 miles I had an issue with a random misfire on light throttle and spark plugs melting. Truck is a 2007 5.4 3v with 170,000.

I replaced coil packs and even a couple individual plugs to no avail. I had begun to think it was a fuel related issue, but after reading the posts in this thread by F150Torqued, https://www.f150online.com/forums/v8...ml#post5159499, I decided to send him a PM and get some more advice on cleaning the plug holes out. He was nice enough to respond and let me know how he made the contraption that cleans out the plug holes. After following his advice, I was able to get all 8 plugs changed and cleaned the holes out, and all the new plugs screwed in down to the seat easily. The plugs were melting because the carbon in the plug holes was preventing them from screwing all the way down.

The truck now runs great, and I am a firm believer now that the carbon in the plug holes is more problematic than just making the plugs difficult to remove.

Big thanks to F150Torqued for the help, and hopefully this helps someone out!

F150Torqued's device to clean carbon out of plug wells. Coat hanger with cloth soaked in carb cleaner on the end. Other end goes in a drill.

You can kind of see the carbon in the plug hole in this picture before it was cleaned.
Old 04-08-2019, 10:19 AM
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Post MORE about 5.4L MISFIRES

Thank you @sean serafini for the generous and gracious acknowledgement. My reward will be if your truck performs like mine has by using the described procedure at each plug change (at ~ 60k mile intervals) since. It never made sense why this generation truck developed this problem only after accumulation of significant miles. ACCUMULATION became the key word. Accumulation of carbon around the plug tip - not miles per se. I'm convinced that changes the plug dynamics - most likely heat range. But definitely its spark efficiency.

I'm at 243,000 miles (31k post timing job) and my ole '04 runs like a top, quiet as a Swiss watch, and routinely runs 50 - 60 - even sometimes 70 or 80 drive cycles without registering A SINGLE MISFIRE.

My struggle lead to the research and development of a dashboard (pictured below) for my the Torque Pro (Android app OBDII scanner) for monitoring live Misfires BY CYLINDER, along with a number of other misfire parameters.

Torque Pro Screenshot @75 MFF_0_CNt (drive cycles since misfire).

For any Torque Pro users are interested in creating themselves a dashboard like this, I am attaching a downloadable 'CSV' file contining the custom OBDII PIDs for the pictured dashboard. It can be copied to the .Torque\extendedPIDs folder on your Android device, then go to >Settings, >Manage Extre PIDs-Sensors, then press menu - >ADD PREDEFINED LIST and the file name will appear in the list for selection.

If you prefer to enter the PIDs manually, detailed PID numbers with Torque Pro equations and a detailed description of the dashboard is posted on the Torque Pro Forum here: https://torque-bhp.com/forums/?wpfor...opic&t=10826.0

Happy torqueing everyone
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Last edited by F150Torqued; 04-08-2019 at 10:22 AM.
Old 04-08-2019, 11:42 AM
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Thanks for sharing!
Old 04-08-2019, 12:33 PM
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Good to know too!

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