2007 Ford Explorer 4.0L Eddie Bauer 4wd Rough Idle / Surge at highway speed

[holy_moly10]

All, Just thought I would share what I found with my 2007 Ford Explorer 4.0L Eddie Bauer 4x4, maybe it will save you some $$ and some hassle:

Presently, my EXP has ~202,000 miles and she's been a good ol' bird. 1 owner so I know everything that's ever happened to it and I have to say I've gotten my money's worth. On the other hand for the past 40k miles or so I've been dealing with some rough idle issues that have gotten progressively worse and finally needed to be addressed.

It started out with a once in a while occurance of rough idle just after start up, then, sometimes when cold the engine would surge a bit just as I'd put the Trans into reverse and it would 'slam' into reverse. Both of these occurances were intermittent and only occurred when cold. The remainder of the time my EXP would purr like a kitten. None of these occurances would trigger a trouble code

About 5k miles ago, I started to notice a strange engine surging behavior when at cruising speeds. It happened from approx 65-70 mph, and it was pretty pronounced. Engine RPMs would jump up and down approx. 400 rpms and it was noticeable in the drive of the vehicle. Not bad enough to need to stop driving, but definately noticeable.

I did a bunch of research and found lots of stuff on the WWW (if people still call it that). First was some TSB's for this version of explorer and some known shifting problems which can be solved by a reflash of the PCM. I checked with my trans shop, and this was not the issue. Next I heard about the Throttle Position Sensor as a possible cause. to be continued...

So I bought a new Motorcraft TPS from Rock Auto and followed the instructions on how to replace it. It's super important to heat up the aluminum throttle body housing before trying to take the screws out of the TPS -- you can find youtube videos about that.

What I DIDN'T do that I SHOULD HAVE DONE -- was to run a re-learn procedure so the PCM could sync with the new TPS. Looking back, I'm 100% convinced this was a fatal flaw.

Anyway--I simply installed the TPS into the throttle body and started my EXP up. Just this step alone made an improvement. It pretty much eliminated the surging issue at highway speeds...but the cold start idle was no better, in fact probably worse

Not knowing that my continuing problems (rough cold start idle) were probably related to not having run the PCM relearn procedure..I did more research and talked to various auto parts store techs... everybody and their brother were convinced that I needed to replace my idle air control module. I was convinced that these 'drive by wire' versions of the explorer (2005 and newer) didn't have one--but many people convinced me otherwise. So I found that you can buy a replacement throttle position motor and decided to give it a run... that was another mistake. I removed the throttle position motor and the spring and gears inside came out. It goes back together pretty easily, but at this point mine was shot.

Simplest solution of all--replace the throttle body, do the relearn procedure...and you're home-free. 2 weeks now and now additional trouble.

 

[Explorer_PL]

Thanks HM.

What are the steps for relearning ?

Is it dealer programming it or just steps an owner can take ?

 

[holy_moly10]

Good point. The relearn procedure is pretty simple (you can find videos about this on youtube):

1. Disconnect negative battery cable from the battery and secure it so that it can't swing back and come back in contact with the negative battery post
2. Connect a jumper wire from the negative battery terminal on the vehicle (not the battery post) to the positive cable/post on the battery. (you don't have to remove the positive cable from the battery as long as you follow step 1)
3. Leave the jumper connected for ~5 minutes
4. Disconnect Jumper and reconnect the negative battery cable to the battery post
5. Key on for approx. 15 seconds (enough time for the instrument panel to go through all of it's various checks during start up)
6. Start up the engine and let it run at idle for ~10 mins
7. Test drive to relearn all of the shift points, go to an open road, accelerate moderately through all of the gears, stop, do it again
8. End

Again--credit to lots of people on the internet because I didn't learn this on my own, but I thought it would be useful for me to tie this solution directly to my EXP symptoms in case somebody else was having the same problems

 

[SteveOReno]

How does the throttle position affect idle? Or maybe it doesn't? Maybe the PCM reset (relearn) fixed your rough idle which was unrelated to the throttle position. I would be interested to find out if the rough idle returns after several weeks.