My 4.6L engine idles fine and drives without issues utill warmed up. At operating temperature, the engine 'hesitates' or misfires' intermittently under load with light throttle. It does not have this problem at idle or with heavier throttle. I have replaced all the spark plugs and COP's and cleaned the MAF with no change in symptoms. There check engine light is not illuminated and there are no codes when I hook up an OBD II reader.
Did it occur the MAF (will not set code) is defective or the fuel pressure is low?
Testimonial: "I thought about low fuel pressure (clogged filter?) but wouldn't this affect heavier throttle performance as well? I'll look into the defective MAF. Thanks."
No I seen dozens that would barely run off idle. Don't guess check the fuel pressure with a load on the engine and monitor the MAF signal as well to make sure it stays within specs.
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SOURCE: Check engine light comes on. p0171 and p0351 codes found
From Lusty Kid:
I know the economy is bad, but change all of the plugs. Check your PCV Valve hose, 150 rottens them out allowing air to be sucked in, thus all kinds of codes.
Depending on mileage. Dismount the EGR valve and clean passages. If you are really good dismount the throtle position sensor body and clean out passages with Choke Cleaner., dismount where the EGR valves connects to the engine, clean out passages. Also check the hose thats behind this mounting to ensure is not clogged. If clogged clean it out. If not replace it. Is about 1.5 ft. long, connects to the PCV Valve Hose.
When is the last time you change your harness. Can't remember??? Replace it. Good Luck
SOURCE: Engine surge during warm up.
Try changing your PCV valve make sure the hose is clean and not full of oil. Also check the elbow end that goes to the intake they tend to collapse from oil saturation. Hope this helps.
SOURCE: 2002 Explorer: Check engine light
Advance and autozone will check your computer for free. It sounds like you have a misfire in one of the cylinders. This can happen because of a burned spark plug wire, fouled out plug, or a bad coil. Hope this helps.
SOURCE: 06 5.4l misfire under load , loss of power
bad coil have some one w/ areal scanner ck. ur codes pid53 ull find it
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