Shaking
Tuned
Joined: Jan 2011
Posts: 297
Likes: 6
From: Birmingham, AL
Failing plugs usually will misfire when under load only. Does it get worse as you hit a hill? Mine shook like crazy in O/D going up hills at 45-50 MPH and when I took it out of O/D to take low RPM load off of the engine, it cleared up right away. I can almost guarantee your issue is the same one I had. I replaced my spark plugs and it hasn't happened since. That was 44,000 miles ago.
One thing I want to mention; If you're not familiar with the spark plug design on these year 5.4s. These are not your regular spark plugs. They have a 2 piece design and the bottom piece of the plug is a porcelain shell that can break off in the head during removal due to carbon seizing it into the well. There is an extractor tool by Lisle part #65600 to extract the shell. There are some good videos on YouTube showing proper procedure for spark plug removal, shell extraction with the Lisle tool, etc. I also recommend running a few tanks of Chevron Techron before tackling this job, which will help to break loose the carbon from the porcelain shell.
One thing I want to mention; If you're not familiar with the spark plug design on these year 5.4s. These are not your regular spark plugs. They have a 2 piece design and the bottom piece of the plug is a porcelain shell that can break off in the head during removal due to carbon seizing it into the well. There is an extractor tool by Lisle part #65600 to extract the shell. There are some good videos on YouTube showing proper procedure for spark plug removal, shell extraction with the Lisle tool, etc. I also recommend running a few tanks of Chevron Techron before tackling this job, which will help to break loose the carbon from the porcelain shell.
Mountain Pass
Joined: Apr 2008
Posts: 127
Likes: 3
I had the exact problem a few months ago. Changed the plugs and all has been well for 4,000 miles. I used original motorcraft plugs as i read here that after market plugs xometimes failed...good luck.
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Freshman User
Joined: Oct 2015
Posts: 31
Likes: 0
Yep, plugs should clear you right up. I bet if you hooked up an obd reader and observed misfires, you'll see the counts increase as it shakes. Plug change out is a piece of cake just take your time and keep the beer cold and plentiful!
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Senior User
Joined: Jan 2005
Posts: 277
Likes: 1
From: San Antonio, Texas
Would this throw a code? My is doing the same thing but doesn't show problem codes. I cleaned throttle body and MAF, changed fuel filter, cleaned air filter, etc. and it still shudders under acceleration.
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makuloco2000
Explorer, Sport Trac, Mountaineer & Aviator
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Nov 20, 2013 08:43 PM