I have a 2002 f150 2wd 4.2l engine.
With 135,000 miles
I just replaced the battery about 300 miles ago and I usually tow a trailer almost always.
Also I replaced the Plugs and Plug wires about 15,000 miles ago
When I am towing I turn the OD off.
Now the problem.
I noticed that when I am not towing now that when approaching highway speeds it seems to shift back and forth from overdrive while accelerating only. But when pulling a trailer with OD off it shifts fine.
No engine codes appear.
I am due to service the transmission fluid I think I have about 35,000 on the fluid now but before I do I just want to pass this by anyone that while I have the pan out. Is there anything else I should check or could this just be a issue with dirty fluid
Or Possibly the drivetrain controller because I hardly ever drive without towing.

BTW Everyone great site I have been lurking here for a short time but I find a lot of useful information here.

 

2 thoughts:

1. This is the beginning of your transmission going out. This is how mine began showing signs before it started grinding going between third and OD. This problem would require a rebuild.

2. You have a slight missfire that makes it feel as if the tranny is slipping. Misfires commonly occur when under load at low RPM's.

I think #1 is more likely, so I would drive with OD off until you can get it looked at or you can just drive with it off if you can stomach the increase in the gas bill. You are likely looking at $2000 if it is the tranny. Sorry, but 130,000 is probably around average for a truck tranny that tows often.

 

Thanks for the reply.
I am leaning towards the tranny issue myself.
I would think if I had a misfire problem, sooner or later I would have a engine code appear.
I guess the coil pack could have some problems!

Since I am planning on a fluid change anyway, and my cheape manual does not give me any info for troubleshooting the tranny I was hoping someone would provide some insight on additional check points to look for.

 

It indeed sounds as if the transmission is going "South"... This could be either a front pump problem,or torque converter issue.Of course there are any number of issues that could be causing the problem. The only reason I said Torque converter,is that OD(or 4th gear) is basically a Torque converter lockout that makes the drive system directly coupled(while in Overdrive).If you have the tranny rebuilt,the torque converter should be replaced as well.
If you have the tools,and "savy" one of our sponsors(rockauto) has a rebuild kit for the transmission....you could concievably get a manual on the tranny,study it,and rebuild it yourself....otherwise it will indeed run around 2 grand to have it professionally done.

 

Just a note, misfires, especially small ones will not always trip a code. It is weird how stupid little things will trip it, but not important stuff like a misfire. Anyway, like mentioned, I think tranny is probably the problem and unless you are an experienced mechanic, I would take it to a shop. The tranny is by far the hardest thing to work on in my opinion. I would never dare touch it except changing fluid.

 

Rebuilding it myself is probably out of the question since I use it every day so the savings I would get would be offset by what business I loose while I am trying to save a few bucks doing it myself.
Since I hardly ever ever use it without towing I guess I could get by for a little while.

Oh well the cost of doing business!

 

The 4R70W shift pattern is 1,2,3,TC lockup, 4th (OD).
You say the problem doesn't occur w/OD off. In this case it never shifts into 4th (OD). W/OD on it appears you're saying that it may be hunting between TC lockup and 4th. It's quite possible that it's a precurser to the tranny failing but it could also be an indicator that the fluid has lost it's additives. Towing definitely runs the fluid hotter which inturn quickens the additives demise.
I recently had a problem where my tranny would hunt or slip w/OD off but work fine w/OD on (opposite of your problem) and a clean and flush corrected it. I have approx 125k on the odometer.
I would start w/a clean & flush then go from there.
Good luck

 

I had a spark plug crack at the top and was about ½ inch long on my 4.2. The truck run fine until it tried to downshift out of od and did not do it if I locked it out of od. This only happened between 45 and 60 mph. I had no codes and the plug looked good. Good luck

 

I would go ahead and change the trans fluid. Make sure you drain the torque converter too (if it has a plug). What kind of plugs and wires did you use? Anything other than factory Motorcraft would be suspect.

 

Every Ford truck I've used for towing with an OD tranny did this....changing the fluid and filter has always cured it. Don't forget to change the fluid in the torque converter, pull the dust cover from the front of the bellhousing and using a large screwdriver or small prybar turn the engine till the plug on the outermost swell of the converter is straight down. There is a rubber plug in the bottom of the bellhousing pop it out pull the plug and go get a beer.....it's gonna take awhile to drain. The fluid breaks down just like oil will. Like I said this has always cured the stutter. Later Whit PS I know this is an old post but my 01 Screw has just started the stutter in the last week and I've got to change it again (212000 miles I usually change it every 50000 but was lazy this time around and haven't done it in about 75000) but it struck home to me.

 

Just as a update to everyone.
I took the truck to jiffylube, Had a fluid exchange done. It seems to have eliminated the problem at least 99.9 percent. As to ignition issues I do not have OEM parts on the plugs and plug wires but maybe I have a coil pack issue also. It does not seem to be a shifting issue anymore but more of a shudder when decelerating to a stop while in the same gear.
Seems to miss a bit at the last moment when stopping.

 

Thanks for the info, mine is doing the exact same thing.
BTW: 2004 F-150, 4.6, 140K, tows quite a bit. Hunts shifting into Overdrive at moderate (under 60mph) speeds.

Question: Do yall recommend using an additive like Lucas when doing the transmission fluid change?