Alright, I have had this happen about five times. I replaced the spark plug and goes away for 4-5 months and it's back again. The plugs and plug wires (MOTORCRAFT!) are less than 2 years old. Only the #4 cylinder missfires. The sprak plug boot has like water (white) stains on it, NOT rust. Is there another way water can get in/down there? The heater hose just above it was loose and I tightened it up, it just would drip once in a while. I see a heater pipe comming out of the intake (back side of intake runner for #4) is this a factor?? Anyone else have the same problem? This is THE ONLY problem I have with the truck, it's just a pain in the pa-toot-ty to R&R the plug every 4-5 months???? I have R&R'd the DPVE sensor and no joy. DO the EGR valves acutally go bad!! That is another part of the (EGR low flow code.) I have changed the coil backs on each bank (had a buddy off on a trip and ripped them off for a test) and no luck!
That was about two times ago. I wish it could have been that easy. Unless I am chasing a gremlin around, everything I fix is the cause until something else breaks, leaks, spits,
URN8's on that plug??
I've got a 1999 with a miss that comes around about once a year or so - new wires fixes it every time. The last time I spent the extra $$$ and bought Ford Racing 8.8mm wires. It ran great - for about year. it's got a slight miss / stumble on the low-end of acceleration now (again), and I'm willing to bet it's the wires again. It always is.
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1999 F-150 XL, Extended Cab, Long bed, 4.6L, 4x4, M5OD (geez, the truck's description is just about as long as the truck itself! )
Your EGR code may be the EGR ports are plugged with carbon buid up. I also had the leak problem. I tightened the hose and the leak and bad wire problem went away. Cleaned the carbon out of the ports and the EGR problem went away.
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'04 Explorer XLS 4.0
'98 Expedition XLT 4.6
'86 F-150 5.0
'79 F-250 4x4
'55 F-350 Dually, waiting to put the '79 gear under the '55.
'95 F250XL 4x4 5.8 Auto, work truck w/plow
Bought the Throttle body/Intake gaskets, had already made my mind up pulling the TB off and cleaning EGR port out. Have a tube of white Lit. grease. I'll do both and let you know how it shakes out.
When I took mine apart post 110k miles, I found my EGR ports were clean - one totally, and one had a spider-web-thin piece of carbon in it. Must be from the MMO and Seafoam I've sucked in to the vacuum hoses and throttle body at different times to clean it out.
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1999 F-150 XL, Extended Cab, Long bed, 4.6L, 4x4, M5OD (geez, the truck's description is just about as long as the truck itself! )
The last time this happened to me, 98 F150 4.6L 4x4, my mechanics scanner actually said to check the heater hose connections as they are prone to becoming loose and leaking coolant onto the #4 plug. Sure enough that was the problem again. Now every time I change oil I check the hose clamps.
It hasn't leaked in a year or so.. (?) the water is like condensation (?) clean not w/anitfreeze. But I do check it every so often. I'm not expecting to find a plugged up port, wish it would be that easy.
97 4.6L #4 Miss-fire! A G A I N.
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