4.6L RPM surging at low throttle 35-45mph, ECM vacuum erratic | Ford Explorer Forums
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4.6L RPM surging at low throttle 35-45mph, ECM vacuum erratic

T

tojan19

Active Member
Joined
August 28, 2003
Messages
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City, State
Smithfield VA
Year, Model & Trim Level
06 EB
I noticed that while cruising at 35-45 MPH, w/ and w/o cruise control on, rpm is sporadically kicking up 1-200 rpm. I got a bluetooth ODB2 scanner and put Torque on my phone. Just learning to use it, but it is showing vacuum all over the place with no changes in throttle position. While driving it is sometimes even saying I'm under boost! I'm guessing a map sensor going bad?

4.6L 2006 Explorer, 125,000miles.
Plugs replaced at 95k, and one coil.
 



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Does it want to idle higher than normal once the engine is up to temp.? Is the vacuum erratic at idle and hot? If that is the case then you have a vacuum leak somewhere otherwise I would say that you have another coil/coils that is/are going bad.
 






tojan19 said:
I noticed that while cruising at 35-45 MPH, w/ and w/o cruise control on, rpm is sporadically kicking up 1-200 rpm. I got a bluetooth ODB2 scanner and put Torque on my phone. Just learning to use it, but it is showing vacuum all over the place with no changes in throttle position. While driving it is sometimes even saying I'm under boost! I'm guessing a map sensor going bad?

4.6L 2006 Explorer, 125,000miles.
Plugs replaced at 95k, and one coil.
Click to expand...

Hi Trojan, sorry to resurrect this thread from the past, but I'm just wondering if you ever figured out what was causing this issue?
 






My PCM was going bad. I chased ghost problems for 6+ months, replaced half my sensors, several trips to the dealer for diagnoses until the computer completely gave up the ghost. I was ready to light the Ex on fire. It's been awesome again since then.
 






Oh my... I'm experiencing this same exact problem with cruise control on or off. The PCM is what, like $800-$900 used? I wish I had one to test out to be sure it's the issue...

How did you know it had completely failed?
 






3rd trip to the dealership after I wouldn't run well enough to drive, it had communication errors and they declared it dead. FLAGSHIP ONE for the ECM, $262
 






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