98 4.6 Backfiring under WOT
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Junior Member
Joined: Apr 2005
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98 4.6 Backfiring under WOT
Hey guys,
Hope you can help. I am having a dilemma with my f150 as of late. About a year ago I had a bad head gasket, changed both sides resurfaced the heads and gave the whole engine a good thorough cleaning. Lately, I have noticed a backfire/miss at the same time when under a good throttle load or WOT. It is annoying cause my engine has a lot of life and sounds sick when thsi happens. She currently has 146,000 miles and does'nt burn any oil since I also changed the valve seals at the same time of the head job. I am running dual flowmasters out the back as well. Plugs, wires, and PCV have all been changed about a year ago with Motorcraft after learning that autozone's crap does;nt cut it. MAF has been cleaned as well as the throttle body cleaning procedure was quite clogged with gunk. I dunno what to do, I was thinking of changing the O2 sensors in the front but was wondering if there could be another less expensive culprit prior to those O2 sensors. I wish it would throw a code cause she is driving me nuts.
Please help.
Hope you can help. I am having a dilemma with my f150 as of late. About a year ago I had a bad head gasket, changed both sides resurfaced the heads and gave the whole engine a good thorough cleaning. Lately, I have noticed a backfire/miss at the same time when under a good throttle load or WOT. It is annoying cause my engine has a lot of life and sounds sick when thsi happens. She currently has 146,000 miles and does'nt burn any oil since I also changed the valve seals at the same time of the head job. I am running dual flowmasters out the back as well. Plugs, wires, and PCV have all been changed about a year ago with Motorcraft after learning that autozone's crap does;nt cut it. MAF has been cleaned as well as the throttle body cleaning procedure was quite clogged with gunk. I dunno what to do, I was thinking of changing the O2 sensors in the front but was wondering if there could be another less expensive culprit prior to those O2 sensors. I wish it would throw a code cause she is driving me nuts.
Please help.
Senior Member
Joined: Jul 2004
Posts: 6,200
Likes: 39
From: Easton, Pa.
I would look at the fuel pressure with a gauge.
Under wide open throttle your on the fixed fuel tables. If there is not enough fuel, the engine goes lean and could cause backfire.
EGR should be closed and not cause any problem. Plugs, wires and coil pack could become involved if they have not already been changed.
Ox sensors are not doing any control function during WOT.
Under wide open throttle your on the fixed fuel tables. If there is not enough fuel, the engine goes lean and could cause backfire.
EGR should be closed and not cause any problem. Plugs, wires and coil pack could become involved if they have not already been changed.
Ox sensors are not doing any control function during WOT.
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Junior Member
Joined: Apr 2005
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tks Bluegrass,
Talked to a ford tech today after twisting his arm. LOL! He mentioned the same thing. He also mentioned the possibility of improperly gapped plug or arcing plug wire even though both are only a year old. We'll see what pans out tonight, I am gonna check the plugs first and then the fuel.
Talked to a ford tech today after twisting his arm. LOL! He mentioned the same thing. He also mentioned the possibility of improperly gapped plug or arcing plug wire even though both are only a year old. We'll see what pans out tonight, I am gonna check the plugs first and then the fuel.