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Infrequent stumbling at low speeds / leaving traffic lights


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Ok, I am STILL wrestling with this one and am hoping theres some new faces here that might have seen this. Mines a 2010 with now 37,000 miles (had 14,000 when I bought it). Ever since I bought the car, about 2-3 times per month, it will just start stumbling badly either leaving a light at an intersection or in stop and go traffic (low speeds). I go to hit the gas (normal driving, not racing) and it starts shaking and stumbling like its firing on 3 cylinders or something. Its not the engine. I can throw the car down into 'M' and it stops immediately. Put it back into auto and the problem is gone. I have had the TSB done for replacing some sort of 'body' in the tranny (sorry I am not a car mechanic :-). They have also done the spark plug TSB and reflashed to the latest tune. Problem is, its infrequent, so it wont do it when they try to find it. I REALLY am ready to order LMS tuner and tunes, but I would like to see this problem gone before I modify the tune on this car. Anybody else seen this?

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I've seen this from time to time. Honestly, when I'm in the set up you are in with it I find smooth applications of the throttle and there is no problem. It's almost like if I get forceful with the throttle (not flooring it mind you) it seems like the tranny "bites" harder to get ready to go. I might not be making any sense but as long as I'm smooth on the throttle I have no bumps. My car is tuned and it still happens sparsely when I get forceful with the throttle in low speeds like you describe.

 

From a stop to WOT there is no problems. It is only when low speeds.

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Thanks man but this is definitely NOT any forcefulness at all. Just the opposite. This is just lightly pressing the gas, like in stop and go traffic or when the cars in front of you are just starting to go at a green light. That's not 100%, but most of the times this happens, thats the scenario. What I'm scared of is it doing one time when I go balls deep with the gas to race somebody from the light and somethings going to snap in the tranny :-(.

 

 

I've seen this from time to time. Honestly, when I'm in the set up you are in with it I find smooth applications of the throttle and there is no problem. It's almost like if I get forceful with the throttle (not flooring it mind you) it seems like the tranny "bites" harder to get ready to go. I might not be making any sense but as long as I'm smooth on the throttle I have no bumps. My car is tuned and it still happens sparsely when I get forceful with the throttle in low speeds like you describe.

 

From a stop to WOT there is no problems. It is only when low speeds.

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If anybody has experience with the spark plug TSB symptoms, thats almost just what it feels like. Stumbling like you are on only a couple of cylinders. However its different in that you can quickly drop the car into manual mode and it clears up. Wish I could find somebody thats experienced this and gotten it fixed somehow. Starting to feel hopeless.

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I am almost inclined to agree w/ you (in the aspect of the plugs)....

 

I wonder if even the most current round of plugs installed pursuant the TSB, may have faltered in some manner?

 

One would be inclined to think not, but hell, stranger things have happened i'm sure.

 

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Yeah but it doesn't make sense, cause when I push into manual mode it clears up immediately.

 

 

I am almost inclined to agree w/ you (in the aspect of the plugs)....

 

I wonder if even the most current round of plugs installed pursuant the TSB, may have faltered in some manner?

 

One would be inclined to think not, but hell, stranger things have happened i'm sure.

 

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Thats what I thought was happening to mine... Now think it is the ethanol in the gas. Today, it was 86, and I put 2 cans of Seafoam in my G8, with a 1/8 tank of gas. Filled it up at a Pilot (91 instead of Murphy 93) and about 20 mi I had it stall on me. All the boats on our lake are having issues with vapor lock (likely too much ethanol) no matter whether they are carbs or F.I.. So... am beginning to think local terminal is putting more than 10% ethanol in our gas. Issue with our EB systems is that they do not have a return to tank, but are return-less, which means if there is any issue with fuel, it can't resolve (refresh) itself by pumping excess fuel back to the tank.

 

Flex still sitting in shop at dealer... they haven't been able to check it for 2 days... and service manager turns out to be a friend of my son. They have been overwhelmed and short handed. Guess I can't bitch... When checking car out today, they had at least 300 EB F-150's and 10-15 Diesels... and town is about 1,000 pop. RICH farmers... I guess!

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Thanks guys. I have previously checked the knock sensor wires, but they didn't look to be rubbing at all. I am going to take another look, simply because this really seems like something that could be caused by an intermittent short or something. Thanks for the link and I will scrutinize this time when I look. Will let you all know if I ever figure it out.

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So I just went and looked, and I gotta say I don't see any wires, anywhere near any metal in my engine compartment? Also, I thought a little more. Tell me if my logics bad here; if I can put the car in manual mode and the stumbling immediately ceases, wouldn't that point to something related to the the tranny and not the engine?

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  • 1 month later...

I just read your thread and I agree we probably are going through the same thing. I'm now kicking myself for not putting it in manual on my trip. I will try that for sure at the next occurance. Why mine acted up only on the start of a trip leg and not in every day driving is still a mystery for me. Did you say you thought there was a 4+ connection? I have noticed that when I run 4+ I get a "grade assist" / manual option that is not there in stock or in Stage 2 or 3. I wonder if you have that also. Some running 4+ do not have the grade assist. Maybe a connection with the stumble there? The grade assist feature makes driving in manual pretty painless as shifting is still auto unless the paddles are touched. If manual mode cures the occasional random bouts of stumble I think it would show a clear connection to 4+. Like you I think the symptoms feel like tranny programming and brief transitory confusion. I'd sure like to figure this out.

 

 

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I have just re-loaded the 4+ tune back on this weekend. I do admit that when the 4+ tune is on, I notice much higher frequency of 'stumbles' and even completely slipping out of gear every now and then. As usual, this is in stop and go or just crawling along at a long traffic light or something. I will put mine in manual and look for the 'grade assist' you mentioned. Where exactly do you see this??

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If you have this capability, when you pull it into manual, you will see an icon of a car going down hill in the part of the dash that shows your avg. gas mileage or what ever info you select to show up. If you touch a paddle the icon and the capability goes away and you return to normal "manual". If you don't touch a paddle the icon remains and you will shift automatically but more aggressively. Freewheeling is disabled and in my opinion shift points are different. I also believe downshifts are more aggressive. Some of our cars have this and some do not. Some claim thier cars had it stock, most associate it with loading 4+, and some just don't have it. No idea how or why. For me I only have it running 4+. Not stock or 2 or 3.

 

If you are right about the occasional clunky attacks responding to using manual, this might be a kind of band aid fix and more appealing than going back to 2 , 3 or sorry for saying this....stock.

 

 

 

 

 

 

 

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Well it's not like Ford included it in mine. If I never loaded 4+ I would never have seen it. My sister in law has it stock on her '12 Explorer LTD with the 3.5. I think I heard that grade assist has been around for a while...not sure though. Just thinking what if they used the same tranny in different vehicles and offered different capabilities between one model and another controlled by software(tune).

 

 

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Another stumbling attack last nite. Stop and go traffic again and now I'm really paying attention to different details. Almost seems like the first hint of the upcoming bout of stumbles is a a funny feeling at throttle off(coasting) in the stop and go. Really hard to describe better at this point. After the strangeness in the coast, the next light throttle application seems susceptible to a stumble. You were right on with the M clearing things up.

I wonder if it's all a software snafu and putting it into M just kind of resets or reboots the tranny programming.

It really helps me to brainstorm with you all over puzzles like this. It would be so frustrating trying to figure this out alone. Forum is great!!

 

 

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I think I'm having the same problem sort of, mine is mostly with downshifts though. When I first bought the car a few months ago cruising around 30-40 and I gave it even a little gas, it would downshift very quickly 2 gears and take off. Just recently, giving it the same amount of throttle, it would hesitate for atleast a second (by hesitate I mean it felt like it lost a lot of power) then only downshift 1 gear and barely accelerate unless I give it more throttle. Sort of hard to explain, but it is starting to get annoying and I'm planning on taking it to the dealer this week. If they find anything I'll be sure to report back and let you guys know. Stock 2010 non PP with 67k miles btw.

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Yep, mine does that TOO. lol I sometimes feel like I picked up a lemon. Depressing some times. Then, when I stomp it from a light, with the stage 4 tune on it, I like it again, for a lil bit ;-). Mine seemed to start doing what you are doing after one of the Ford Service Dept ECM updates. They cant explain it, and don't want to admit that there's anything wrong.

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I've been getting some stumble as well but it mostly comes with the rear view camera turning on. Sometimes it doesn't come on but I'm pretty sure it's related to this TSB.

 

10-21-02 - 6F50/6F55 TRANSMISSION - SLIP/NEUTRAL OUT, 5TH GEAR START FROM STOP, ELECTRONIC PRNDL ERROR, BACKUP CAMERA IN D - BUILT 3/13/2009-6/30/2010

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