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RPM Surge under light throttle

stonerhino

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Virginia
Year, Model & Trim Level
2004 Explorer v6 XLT
So....

For a long time my 04 XLT 4L has had this weird RPM problem where when parked, I can gently tap the throttle and it the RPM will increase, but it will then immediately reduce the RPM and almost stall. In some cases it does, others it will "bounce" the RPM two or three times until its stable.

Second symptom is that when I gently increase pressure on the throttle, the RPM will increase to about 1000-1100 and suddenly drop to near stall, recover, and repeat the "bounce" until I either increase throttle pressure to 1500 RPM, or take foot off.

Third symptom is that it pulses or jerks when coasting on the highway. Coasting down hills w/ foot applied and cruise control is VERY evident.

During this year's crazy snowpocalypse here in Virginia, 4WD has been needed in a few spots. I got stuck three times because the engine would stall while performing gentle throttle use on maneuvers.

Back in December I had to have a new engine put in. The timing chain jumped on the passenger bank from a misfire on startup. I thought this would go away with a diff engine, but its slightly worse now.

Because of the cold, I have not had an opportunity to check for vacuum leaks. Not getting any codes.
 
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stonerhino

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Well, I seem to have resolved this partially.

I replaced all four O2 sensors, EGR sensor and valve assembly, and Pedal sensor.

It is by no means anywhere near as bad, but now I have other problems to deal with. *sighs* car ownership...
 
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Number4

"I'm counting to 3, then I'm getting your dad."
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04 Ford Explorer 4.6l
In ‘04, the 4.6 went to Drive-by-wire for the throttle. Disconnecting the battery wreaks havoc with the PCM/Throttle.

Not sure about the 4.0 in ‘04.
 
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imp

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In ‘04, the 4.6 went to Drive-by-wire for the throttle. Disconnecting the battery wreaks havoc with the PCM/Throttle.

Not sure about the 4.0 in ‘04.
@Number4
4.0 went drive by wire in 2004. I have had to disconnect my battery innumerable times during a variety of jobs, and do not understand your reference to wreaking havoc. Explain? imp
 
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Number4

"I'm counting to 3, then I'm getting your dad."
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@Number4
4.0 went drive by wire in 2004. I have had to disconnect my battery innumerable times during a variety of jobs, and do not understand your reference to wreaking havoc. Explain? imp
It’s a V8 thing then. Doing so with the 4.6, the computer loses its memory on a crudy butterfly valve. Causes two things, near engine stall at idle, extra pedal effort to over come the crud (which causes a surge when excelerating from a stop.) Too much oil entering the throttle body.

Ford has a TSB on it for Explorers with just 10k miles on them.
 
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mountaineer2004

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2004 Mountaineer (AWD V8)
^^^ Absolutely true. I had Ford do work at 100k, including replacing battery. When I got the car back, the idle dropped and nearly stalled at every stop. That didn't happen before. I brought it back to dealership and they fixed it by cleaning the throttle body, if I recall correctly.
 
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