Lurching at a stop, bogging when idling | Ford Explorer - Ford Ranger Forums - Serious Explorations

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Lurching at a stop, bogging when idling

Ulenran

New Member
Joined
December 22, 2020
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City, State
SAGLE, ID
Year, Model & Trim Level
2002 Ford Explorer 4. XLT
Hi all, I've got a 2002 Explorer 4.0 w/ auto trans. Truck starts with a higher than normal surge (up to about 2000 RPM), then settles down to a normal idle... but only for a minute. After a minute or so, it starts bogging down to 400 RPM, then back up to 1000. While this is happening, the engine sounds like it is misfiring, but my scan-tool does not detect any misfire events at all. This happens several times, before finally seeming to correct itself and running right (about 750-800 RPM). Engine continues to run ok for 5-10 minutes, then repeats the bogging-surging process again. Sometimes it bogs down enough to stop the engine. This is only what happens while IDLING, however.

While driving in the morning, when it is cooler, the engine typically has no issues and will perform perfectly (unless coming to a stop and being placed in PARK or NEUTRAL, then the aforementioned issue may begin to happen). When driving in the afternoon, especially with several stops in town (engine shut off while running errands, etc.), the engine will begin to shudder hard and RPMs will jump repeatedly when at a stop while in DRIVE, causing the vehicle to lurch forward, requiring major pressure on the brakes to hold it still. When attempting to accelerate from a stop when this has occurred, the engine suddenly refuses to accelerate, with RPMs dropping to below normal idle levels and will not "get up and go" without pumping accelerator. This does not happen everytime the vehicle comes to a stop, but the air temp and the amount of times the engine has been turned off and back on again within a short amount of time seems to increase the chance of this happening.

My wife loves her explorer, but I am worried the lurching will cause her to hit someone, or the lack of acceleration cause someone to hit her....

I do all my own work on my vehicles, and am more than just a backyard mechanic. within the last 20,000 miles on this rig, I have replaced the PCV, EGR solenoid, O2 sensors, crankshaft position sensor, throttle position sensor, valve cover gaskets, intake manifold gaskets, all the vacuum lines, cleaned the MAF, IAC, throttle body, EGR valve, and entire intake manifold. I replaced entire engine 32,000 miles ago with a good used engine. Everything I have replaced has been to track down this issue/s. I have performed computer reset after every repair as per the Haynes manual.

Sorry for the long post, but I am tired of throwing parts and time at this potentially dangerous issue, but am also not wanting to buy a "new" car when I have done so much already... Here is a cookie for reading this far!!! 🍪
 
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