2002 Ford Explorer loping idle

Tiny
CHRIS HAZELWOOD
  • MEMBER
  • 2002 FORD EXPLORER
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 146,000 MILES
My son has an explorer with 4.0 SOHC that has a lope and eventually stalls at idle. If you give alittle gas it idles smooth. I have checked cold pack, all plug wires have spark.
OBDII said misfire cylinder 2 & 6.
Changes spark plugs, eliminqted coeds, still lopes at idle and after 5 minutes will stall.
? Suggestions to check next.
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Thursday, April 15th, 2010 AT 6:37 PM

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Tiny
DAVE H
  • EXPERT
Hello .. thanks for the donation .. much appreciated

I would replace the coil pack for plugs 2 and 6 !

Coil Pack System
The EI system consists of a CKP sensor, coil pack(s), related wiring and PCM. The CKP sensor is used by PCM to indicate crankshaft position and speed by sensing a missing tooth on a pulse wheel mounted on front of crankshaft. The coil pack receives the signal from the PCM to fire at a calculated spark target. Each coil within the pack fires 2 spark plugs at the same time.
The plugs are paired so one plug is fired on the compression stroke, and the other plug fires the mating cylinder, which is on the exhaust stroke. On the next cycle, firing is reversed. On 6-tower coil pack applications the matched cylinder pairs are: No. 1 and 5, No. 2 and 6, and No. 3 and 4. See Fig. 50 and Fig. 51 .
On single 4-tower coil pack applications (4-cylinder), the matched cylinder pairs are No. 1 and 4, and No. 2 and 3. See Fig. 52 and Fig. 53 . On dual 4-tower coil pack applications (8-cylinder), the matched cylinder pairs are No. 1 and 6, No. 3 and 5, No. 4 and 7, and No. 2 and 8. See Fig. 53.
The PCM acts as an electronic switch to ground in the coil primary circuit. When the switch is closed, positive battery voltage applied to the coil primary circuit builds a magnetic field around the primary coil. When the switch opens, power is interrupted and the primary field collapses inducing high voltage in the secondary coil winding and the spark plug is fired.

hope this helps


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Thursday, April 15th, 2010 AT 8:28 PM
Tiny
JACK42
  • MEMBER
Sounds like a possible vacuum leak at the intake manifold (Upper). Use carb cleaner to spray at the base of the upper intake where it meets the lower, especially around the ports for 2 & 6 to see if the idle changes, if so you have a vacuum leak, if not it may be injectors. If you can access them, swap the injectors for 2 or 6 to a different cylinder to see if the miss follows it.
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Thursday, April 15th, 2010 AT 8:29 PM

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