I have a 2007 Ford Explorer 4.0 with rough idle, no check engine light. We've tracked it down to fuel injector but can the rough idle cause erratic shifting with the transmission?
Thanks in advance.

ps. no codes for transmission and no check engine light.

 

I think that a more appropiate way to phrase the question is "can a driveability concern cause a(n) (perceived) transmission problem?" The short answer is yes. Excuse me for being such a fussbucket here, but after working on these forever, the very first think you must have when diagnosing a tranmission problem is a well-running engine, or the vehicle will not even have a chance to run right.
The first thing to do is to get the engine running right. If you have a fuel injector concern at idle, I'd bet a monkey to a mousetrap that the problem is there at all engine speeds, it's just that it smooths out a great deal.
Does the engine lack power? Does it stumble on takeoff? I'd bet that with no CEL, then the problem is not pronouced enough to trip the executive diagnositic monitor yet, but might be getting there.
First, check all the vacuum lines for cracks, breaks, etc. And I find it interesting that you mentioned that you have a injector problem. I've worked on these for a while and with the exception of '05 F series and early 2000 Taurus's, never have I replaced a fuel injector in a ford that didn't set a code or just stop flowing. If you had an injector (even in the early stages of ) sticking open/closed, it would affect the Long term fuel trims, and would trip a code.
Mabye another check would be to check that the compresssion in the affected clyinder is good and that the plug is good and wires are sending spark to the plug ok. This problem is going to be harder to diagnose w/o a CEL, but if you have a scanner that can read pending trouble codes, that might be a worthwhile option.
And yes, the 4/5R55E transmision had it's problems, but you can describle that when you get the engine running right. In Park and nuetral, the tranmisssion has nothing to do with the engine (well, very little, but Hanky can fill you in, I'm sure).

 

I believe greasemark covered it pretty well.
My curiosity gets me in trouble and it has been awakened again.
If I may, how did you determine it was a fuel injector problem?

 

I see why you gentlemen are senior members...thanks for being so informative and here are answers to the questions:
It is not a definitive diagnosis, but rather a technician that I've known for a while and is very experienced checked for codes and since it didn't throw any and he did the scientific method of checking for vacuum leaks...cmon you know, the old spray around vac ports and intake haha. Anyway, there didn't appear to be any vacuum leaks and we took the MAF sensor out and sprayed it good with maf sensor cleaner (although it actually was surprisingly clean).
So he suggested getting a injector prior to pulling it apart and testing the injectors in case that was the issue, we'd have one on hand.
Other than that...the general census has been vacuum leak. I will say that it idled, ran and shifted perfect prior to me changing the plugs and wires.
truck ran perfect but was def overdue for plugs and wires...
Here is the break down for that, I bought the "recommended AMAZING iridium" plugs (garbage) and new wires, installed and it started having this issue (tough luck or awesome coincidence). So I scrapped the "AWESOME IRIDIUM" plugs and went with oem motorcraft plugs (made sure all were gapped)...still had the issue. So I'm not sure if the injector is the issue or what, but what ever it is there hasn't been a CEL yet so I'm stumped?
Thanks again and all the info is greatly appreciated.

 

I doesn't lose power but the shifting is very irregular through all/most gears. No stumble at take off.
we havn't checked compression and I havn't checked wires and thought it would be an anomaly for both sets of plugs to do the same thing (suppose I shouldn't assume)
no scanner for pending codes...
all the problems seemed to arise after changing plugs and wires, the rough idle was first and the tranmission concern followed maybe a few days to a week later. Now I'm not sure if this matters but someone said something regarding the route of the plugs wires could be effecting the idle if the wires are getting interference from the alternator. I did not rerun wires through original path due to the need to move the alternator to do so...(wasn't sure about that prognosis)

 

I think you know what you should do next.
Interference from proximity to the alt can do crazy things. Since the problem arose after changing the wires and plugs, there might be maybe three possibilities.
One could be a bad wire, another could be where you ran the replacement wires. and another possibility could be if the wires are too close to one another.
One last possibility could always be something new just developed at the same time you replaced the parts.
Why not try to place the wires with the same routing as original and see if there is any improvement?

 

Yes, that has crossed my mind several times. The only reason I haven't routed the wires through their original location is because the wires don't rest on the alternator, they are laying up over an open area between the air box and intake. As far the the wires distance apart from each other, they are in there factory looms that separate them maybe a 1/4". so I'll pulled the plugs and check them, and reroute the wires to there original location and see what happens.

Thanks again...

 

And to expound a little on what hanky (that great wealth of correct information), another easy, quick way to check for vacuum leaks is to spray the intake area with carb/brake cleaner and watch if the engine smooths out or picks up speed. I also find it interesting that all this came of a tune up, but who knows what happened during the process. I'm certainly guilty of disturbing something during normal maintanance, with the resultant car running worse then before.
These engines were forever developing vac. leaks due to deteriorating rubber hoses, which was a major concern. However, are you sure that you got the last 2 plug wires on correctly? The output to the plugs from the coils goes 1-2-3-4-6-5 as you look at them, with 3 and 4 being across from one anthoher. It took me about 3 Aerostar tuneups on 4.0L where the coil is on top of the intake with about 1/2" clearance to figure that out. On top of that, they were all hot.
Hope this helps; if not, let us know. I'm sure Hanky has a few more suggestions.

 

any suggestions on easy way to test the wires? I have a light that I can ground and add to the top of the spark plug and cylce...
As I was pondering all the possibilities last night, I thought what If by some weird chance I crossed a wire mixing up the firing order? I doubt it's likely considering I replaced them one by one but I'm just thinking outloud...

 

One other idea if you isolate the alternator: take off the Battery cable and the smaller connector; these alternators can self-excite and create this problem with just the battery wire hooked up. That was another long day...