Hi all,<O</O
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This is my first post on here and I would appreciate any help I can get. I have a 2005 Explorer 4.0L engine, 2wd, & auto trans and the last couple of months I have notice a problem when driving at speeds over 45-50 mph there is a consent slight rev of about 100-200 rpms. The trans seems to shift find, just had a fluid & filter change in the trans & the fluid was clean, no deposits. The engine sounds good and everything drives great. Thanks for your help.<O></O>

 

Try turning overdrive (OD) off and see if the surging goes away. The torque converter may be locking and unlocking. There's at least one other thread on here related to that.

-Rod

 

I tried that a couple of weeks ago and it still did it. I had someone else tell me it could be the a/c compressor, so I turned the a/c off and it stoped for awhile but it started back with it off later on that day.

 

I have a 2006 explorer the torque converter locks and unlocks between 40&55mph under
a light load,replaced converter no change,no codes displayed.Sometimes engine quits
at low speed for no reason and restarts ok.could a TPS cause this without showing a code? Also engine seems to surge very slightly at highway speeds.

 

Maybe you can describe "consent [constant?] slight rev of about 100-200 rpms" better. Do you mean that the engine speed increases increases at a constant rate by 100-200 rpms, then drops back down in a periodic cycle, or that it constantly changes by 100-200 rpms, nearly instantaneously? Do you feel this happening in the vehicle, or would you not notice it if you had the radio volume up and were not watching the tachometer? Does the vehicle speed change accordingly?

-Rod

 

Welcome to the forum. Careful not to try to hijack someone else's thread by asking for help on their thread rather than offering suggestions or simply stating you have the same issue.

How do you know that your converter is locking and unlocking, were you monitoring the torque converter lock status real time with a scan tool in datastream mode or just going off of feel? If datastream, were you also monitoring engine load to see how engine load corresponds to lock/unlock status? If so, did there appear to be a correlation?

-Rod

 

The speed of the vehicle doesn't change, at least I don't think so and you can feel the rev when it happens. I can notice it without looking at the tach. It will rev up and return to the normal rpm until it does it again.

 

My '04 does the same thing.