Slight RPM Fluctuation when shifting into overdrive at low speeds

[holliwood98]

Hey guys, my 2014 Explorer xlt 3.5 (non ecoboost) started doing something a couple days ago, and I'm trying to determine what it is. When taking off in town from a stop and increasing speed slowly, when I get to about 28-30mph, it seems to shift into overdrive then the RPMs start to slightly fluctuate some. It feels like it starts getting a little sluggish, not a smooth increase in speed. Has anyone had this issue? I'm thinking maybe it's the IAC valve or spark plugs (159,000 miles on it and neither have ever been replaced). Any thoughts? I hope its not the IAC valve, because nobody seems to have one in stock and they are on backorder from FORD.

 

[Fix4Dirt]

is the OD band slipping? if ya blip the throttle do the rpms go up more than expected? or is it more of a surge? if so clean TB and clean IAC first

 

[1.8TTony]

Not gonna be the IAC. Not sure what the RPM's are sitting at 39mph in OD, but I know the rpm is not going to be an idle........the engine is going to be running off metered air, TPS and other perimeters. Plus, if the IAC was the culprit, you'd get a code for it.

One thing I would consider is transmission fluid condition. Does this happen when transmission fluid is cold? Warm?

 

[1.8TTony]

Maybe drive it in such a way to maintain this condition for a few miles....and see if a code pops up.

 

[mguy13sport]

Torque converter locking/unlocking will make the rpm surge. I'd scan for codes first

 

[J_C]

At 159K, what drivetrain fluids have you replaced? It is due for them.

At this mileage you are also due for new spark plugs ++ other things if even spark plugs have not been replaced. Ignore Ford's recommendations for lifetime fluids, nothing is lifetime if you want to drive it longer than Ford's warranty period. At this point every fluid in the vehicle should have/been replaced at least once. Considering the situation, I'd start with the transmission fluid, then after changing it, drive a while and wait to see if it clears up.

Edit: Some people say you shouldn't change transmission fluid if it has been this long, research and decide for yourself.

After that, I'd hook up a scan tool capable of ford specific live data and watch that when it happens.

At the very least, replace the spark plugs now as it is due for it anyway, but all the fluids, that is more expensive down the road if you don't do that while spark plugs at worst you eventually get enough misfires to melt the cats, not cheap either but just sayin'... it needs some TLC to minimize problems later.

I don't know about this generation of IAC valve but on my '98, brake cleaner, a little scrubbing, and a drop of oil let slide down the solenoid shaft, has kept my IAC valves working. I wonder though does it even have an IAC as there is no Rock Auto listing for this?

 

[holliwood98]

At 159K, what drivetrain fluids have you replaced? It is due for them.

At this mileage you are also due for new spark plugs ++ other things if even spark plugs have not been replaced. Ignore Ford's recommendations for lifetime fluids, nothing is lifetime if you want to drive it longer than Ford's warranty period. At this point every fluid in the vehicle should have/been replaced at least once. Considering the situation, I'd start with the transmission fluid, then after changing it, drive a while and wait to see if it clears up.

Edit: Some people say you shouldn't change transmission fluid if it has been this long, research and decide for yourself.

After that, I'd hook up a scan tool capable of ford specific live data and watch that when it happens.

At the very least, replace the spark plugs now as it is due for it anyway, but all the fluids, that is more expensive down the road if you don't do that while spark plugs at worst you eventually get enough misfires to melt the cats, not cheap either but just sayin'... it needs some TLC to minimize problems later.

I don't know about this generation of IAC valve but on my '98, brake cleaner, a little scrubbing, and a drop of oil let slide down the solenoid shaft, has kept my IAC valves working. I wonder though does it even have an IAC as there is no Rock Auto listing for this?

My first thought was the IAC valve, which I do plan to look at today and clean. I think Rock Auto doesn't have them, because NOBODY has them right now. Even on Ford parts site, they are on back order. We've owned the car since new, and the oil has always been changed every 5000 miles. I've never had the transmission fluid changed, because it's never been an issue, and YES, like others have stated, I've always been told to not mess with it if I've never had problems. When I accelerate, the RPMs don't necessarily "rev up", it just shudders (jerks a little), or seems like it's not getting enough fuel, but it idles smooth. I do know I need to change the plugs. I have them. Just haven't gotten to that part yet, as I know it requires pulling the top end off to get to the back ones, and I just haven't felt like doing it yet, since I drive it everyday and can only work on it on the weekends, which have been all booked up with my son's baseball and other house remodeling stuff lately. I guess it's time to get on that finally.

 

[holliwood98]

Not gonna be the IAC. Not sure what the RPM's are sitting at 39mph in OD, but I know the rpm is not going to be an idle........the engine is going to be running off metered air, TPS and other perimeters. Plus, if the IAC was the culprit, you'd get a code for it.

One thing I would consider is transmission fluid condition. Does this happen when transmission fluid is cold? Warm?

Since I don't really drive very far in it (I work 10 mins from home), I would say the transmission fluid is usually cold. I haven't driven it for a long time at once yet to see if it clears up, because I don't wanna get too far from home and some go wrong where I'm stranded, because I always have my son with me.

 

[J_C]

We've owned the car since new, and the oil has always been changed every 5000 miles. I've never had the transmission fluid changed, because it's never been an issue, and YES, like others have stated, I've always been told to not mess with it if I've never had problems. When I accelerate, the RPMs don't necessarily "rev up", it just shudders (jerks a little), or seems like it's not getting enough fuel, but it idles smooth.

It's not the IAC if it idles smooth. Fluid changes are preventative, to keep problems from happening, should not wait till there is a problem to change them.

If you have AWD, the PTU should have the fluid changed for sure and may be about like mud by now. If it is very goopy when drained, you should fill with fresh fluid, drive a few hundred miles then drain and fill again. The same goes for the differentials, there is no risk, only benefit to change fluid, while it is the transmission that might slip with fresh fluid. Some people take a gradual approach and replace some of the fluid at a time, then repeat every year or two depending on mileage and operating temperature.

 

[mguy13sport]

You can data log the torque converter lockout using For scan among other things (like shift flare, gear position etc)

 

[Odrapnew]

You state is seems like stutters a bit.
I'd look towards plugs, especially if they are original at 159k miles.

If you have a way to check for misfire counts, that's where I'd start.

My wife's old CX9 would stutter a bit when you'd accelerate on the freeway.
No check engine light, but I was able to log misfire counts and found 1 or 2 cylinders would show incremental misfires after the stutter.
Replaced front 3 plugs and was back to normal. That engine was a Ford engine and also had to pull off intake to get to the back plugs. Since the back ones didn't show any misfire counts, I just did the front 3.

 

[holliwood98]

You state is seems like stutters a bit.
I'd look towards plugs, especially if they are original at 159k miles.

If you have a way to check for misfire counts, that's where I'd start.

My wife's old CX9 would stutter a bit when you'd accelerate on the freeway.
No check engine light, but I was able to log misfire counts and found 1 or 2 cylinders would show incremental misfires after the stutter.
Replaced front 3 plugs and was back to normal. That engine was a Ford engine and also had to pull off intake to get to the back plugs. Since the back ones didn't show any misfire counts, I just did the front 3.

Yeah, I'm grabbing some tranny fluid and new plugs today to change and see if that fixes it. I know she needs a good tune up. I've just been procrastinating, because I don't drive it very far during the week and I've had other responsibilities that have taken all my time and money lately. It's been a great vehicle. Probably the best one we've ever owned, so it's time to get her back to normal so she lasts me at least another 30-40,000 miles