105K miles. Trans never serviced. Trans issues started about a year ago. Mostly mild stuff like a clunk when the trans shifts up to OD or down from OD. My best guess.

More recently, and almost always when hauling a load, trailer or a heavy lawn mower in OD/Off mode, and after fully warmed up, I can be climbing a hill and the van slows down. Adding gas doesn't help and putting the pedal to the floor doesn't help. The RPMs don't rise when adding more gas, so it doesn't seem like the trans is slipping. Also, things like slowing at a stop sign while hot, i add gas and it's in the neutral state. Otherwise, driving around the area on mostly level streets and small hills, with no hauling load, everything works well, just the occasional clunk. The oil is full, good color, and smells like fresh oil.

There is a cooler on this trans. By the way, this issue can just pop out of nowhere and is kind of rare.

I am taking it to a garage to have any codes revealed. Before I change to a Jasper trans, should I drain the oil or check the filter first? I've heard that it's not always a good idea.

Opinions please.

 

4.6L or 5.4L is not specified so I randomly picked 5.4L. Check my signature below to see why.

 

My bad. It's a 4.6L

Thinking about all the plugs makes me want to scream. Sometimes taking them apart and replugging will cure it.

 

2006 E150. 5.4. I am on my 3rd transmission at 300K miles. I would suggest a drain and fill (NOT A FLUSH!). Be very deliberate about the process when you do it! All fluids lose their effectiveness with time. Use ONLY Mercon V !

 

The trans can only deliver the power provided by the engine.. Get the engine to where it can perform then go after the trans.

If you can, change the fluid and filter before winding up-paying someone else to do it.

All of the above are considered routine maintenance. The E series are not the easiest to work on, so that decision is up to you. Don't forget the fuel filter !

Removing the battery seems like a lot of work, but can make changing plugs on that bank a lot more accessible. You will lose some memory, but the pleasure of driving a well performing vehicle is worth the trouble.

 

Based on advice, I'll take it to the garage and have them check for trans codes, which my scanner can't do.

Then check the plugs at the trans which are susceptible to winter salt. Change the oil and check the filter.

I changed all the coil packs a few years back when the #2 went bad. Spark plugs at the same time. The engine has plenty of power even going up our mountains. This trans issue is intermittent and somewhat rare but I don't like the thought of being stranded. But if I can't haul riding mowers for my business, the van is kind of useless, since I have a newer Transit for that, except I'm limited to 46" deck width because of a stupid AC unit in the rear that I can't get rid of.

Thanks for the advice

 

Took it to the garage and had the van tested for any codes my scanner wouldn't catch. There were none. The plug to the trans was exercised and checked for corrosion, none seen. I knew I had a fuel rail sensor code. I kept on thinking about Hankys comment about the fuel filter. The symptoms seemed to match a restricted fuel filter. I know in the 12 years I've owned it, I never changed the filter. Got a NAPA filter and saw my old one was a Motorcraft. Installed it, not too bad of a job.

Tried to blow thru the filter and no-go. Used an air gun to blow thru and no-go. Blew backwards and it opened up. I feel that the filter was the issue. Thanks for the advice.

I'll check in a few days to see if the rail sensor code comes back.

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Final update:

Since I changed the fuel filter, I haven't had a single shifting problem. That's all I did.

It now downshifts automatically when going up hills. No more shifting problems.

I'm guessing the fuel rail pressure sensor has something to do with the transmission computer. I don't know. Everything working great.