Ford F150 - 2005 F150 stutter/dead spot and RPM drop @ 45-60 mph U/Load
11-07-2015, 01:21 PM
#31
LightningRod
OFF THE WALL THEORY re: 5.4L 3v Misfire issue
I KNOW THIS IS AN OLD THREAD, but the bump is worthwhile as it is still a persistent issue.
@BrianSheen , @gameengineer , and everyone experiencing the symptom the OP so perfectly described years ago. After 'fighting' the identical problem for ages - and 'pulling my hair out', I believe I stumbled onto the solution (detailed below). And it is so simple and inexpensive it makes ME shudder. Although proof is elusive, I believe it is a direct byproduct of the problem of spark plugs breaking on removal, and my theory goes a long way to solving THAT problem also. Previously discussed in this post http://www.f150online.com/forums/v8-...ml#post5159499 .
I believe the accumulation of carbon deposits that gets 'packed' very tightly around the barrel of the spark plug _upsets_ the heat range of the spark plug. Also discussed in detail in this post http://www.f150online.com/forums/v8-...ml#post5161039 . The rate of accumulation varies from user / vehicle / fuel contaminates and a number of factors, but seems to always develop or emerge at higher mileage - (about the time plugs need to be changed). But the symptom does not exist on new engines. These carbon deposits are hard and packed in there tight enough to literally twist the plug apart (something that is hard to do intentionally in a bench vice). BUT we then screw new plugs back into that hole that was already so tight the old plug broke off on removal? (Speaking for myself, I did that TWO TIMES trying to fix misfires). Some folks apply anti-seize, which the TSB recommends. But I believe that just insures heat conductivity between the plug and the cylinder head, still negatively effecting heat range of the NEW PLUG. Either way, I believe some new plugs are fractured or damaged on reinstall by the carbon impaction, and the 'undesirable effect' of that still exists. I believe these two factors explain the COMPLETE RANDOMNESS of whether plug changes actually cures the problem or NOT. I also believe this explains WHY changing COPs MAY or MAY NOT be effective.
MY SOLUTION: On my THIRD plug change, I removed all plugs, then rotated the engine to TDC for each cylinder in turn, and thoroughly cleaned the carbon deposits out of the spark plug holes with a brass bristle thread brush, compressed air and B12 Chemtool carb cleaner. The new plugs would screw all the way in to the seat by finger, and I then torqued them appropriately. I did NOTHING else during this plug change (except the battery was disconnected and I did a PCM relearn procedure). Immediately on startup the random, intermittent misfires or thumping under light load around 45-50 mph was gone. 100,000 miles later, and one more plug change using this procedure (without breaking a single plug), I have no misfires @ 210,000 miles. And I have no other explanation for why. But it seems to me it simply puts the combustion chamber back nearer to its original design or new state, and they don't miss when they are new. It certainly doesn't add any appreciable cost to the plug job.
I hope this experience helps someone else. And I would welcome any positive confirmation. BUT USE CAUTION: Don't let this happen http://www.ford-trucks.com/forums/13...lp-piease.html
@BrianSheen , @gameengineer , and everyone experiencing the symptom the OP so perfectly described years ago. After 'fighting' the identical problem for ages - and 'pulling my hair out', I believe I stumbled onto the solution (detailed below). And it is so simple and inexpensive it makes ME shudder. Although proof is elusive, I believe it is a direct byproduct of the problem of spark plugs breaking on removal, and my theory goes a long way to solving THAT problem also. Previously discussed in this post http://www.f150online.com/forums/v8-...ml#post5159499 .
I believe the accumulation of carbon deposits that gets 'packed' very tightly around the barrel of the spark plug _upsets_ the heat range of the spark plug. Also discussed in detail in this post http://www.f150online.com/forums/v8-...ml#post5161039 . The rate of accumulation varies from user / vehicle / fuel contaminates and a number of factors, but seems to always develop or emerge at higher mileage - (about the time plugs need to be changed). But the symptom does not exist on new engines. These carbon deposits are hard and packed in there tight enough to literally twist the plug apart (something that is hard to do intentionally in a bench vice). BUT we then screw new plugs back into that hole that was already so tight the old plug broke off on removal? (Speaking for myself, I did that TWO TIMES trying to fix misfires). Some folks apply anti-seize, which the TSB recommends. But I believe that just insures heat conductivity between the plug and the cylinder head, still negatively effecting heat range of the NEW PLUG. Either way, I believe some new plugs are fractured or damaged on reinstall by the carbon impaction, and the 'undesirable effect' of that still exists. I believe these two factors explain the COMPLETE RANDOMNESS of whether plug changes actually cures the problem or NOT. I also believe this explains WHY changing COPs MAY or MAY NOT be effective.
MY SOLUTION: On my THIRD plug change, I removed all plugs, then rotated the engine to TDC for each cylinder in turn, and thoroughly cleaned the carbon deposits out of the spark plug holes with a brass bristle thread brush, compressed air and B12 Chemtool carb cleaner. The new plugs would screw all the way in to the seat by finger, and I then torqued them appropriately. I did NOTHING else during this plug change (except the battery was disconnected and I did a PCM relearn procedure). Immediately on startup the random, intermittent misfires or thumping under light load around 45-50 mph was gone. 100,000 miles later, and one more plug change using this procedure (without breaking a single plug), I have no misfires @ 210,000 miles. And I have no other explanation for why. But it seems to me it simply puts the combustion chamber back nearer to its original design or new state, and they don't miss when they are new. It certainly doesn't add any appreciable cost to the plug job.
I hope this experience helps someone else. And I would welcome any positive confirmation. BUT USE CAUTION: Don't let this happen http://www.ford-trucks.com/forums/13...lp-piease.html
04-13-2016, 08:55 AM
#32
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Solved my stuttering problem
My truck also had the same issues. I've kinda just ignored it for a few months ( the stuttering wasn't too bad at this point). Just here recently it was stuttering real bad at 45-50. maybe the way the tranny is geared that is its greater load. It even started stuttering lightly down the highway. I never had any codes untill it got worse then I got the typical misfire code, changed #3 coil a runs like the truck I know again. So long story short, I went at least two months with this problem before it would generate a code!