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Discussion Starter #1
Hi all. New to the forum. Lots of good info here. Okay, I have recently purchased a 2001 Excursion with the 7.3/ 4R100 combination. It runs and drives great except for one issue with the transmission. When shifting into third gear (pulling my boat) the tranny seems to make some type of stumble sorta like I'm hitting a large pothole or something. I am familiar with the hard shifts these make because I also own a pickup with the same set up. I have also noticed that when down shifting into passing gear it tends to stumble a bit and not immediately down shift. I did notice that without the boat behind it, the stumble into third seems more like a delayed shift or kinda like a slip. Any advise would be greatly appreciated. Thanks.
 

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Welcome to the forum! The 4R100 expert will be online shortly to answer your question.
 

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I'd look at fuel filters and injectors before the transmission. Engines create stumbles, not transmissions.
 

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I don't know. I also can't come up with any way the transmission can make the engine stumble. I've also never seen a transmission stumble.
 

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I had a huge old gasser that had a tranny issue, and it would not down shift correctly. When I stomped on it , it wouldn't drop a gear , and boy did that big block stumble when it did. Ended up blowing up the transmission and taking it to the wrecker. So never knew what failed when it blew or wouldn't gear down right. No help I know, but it stumbled. I think Mark is just slagging you on your terminology. Meaning, he don't know what your describing. Could it be a shudder? Tranny can definitely do that.
 

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Discussion Starter #7
Okay so maybe stumble isn't the correct description, let's try this. Occasionally when it shifts from second to third pulling my boat it is more than a hard shift. It feels more like a slam into gear. Without the boat it feels like it starts to shift into gear before it actually engages. Kinda like a double shift.
 

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That's a better description. lol. Mark is the tranny expert. Hes your man. Be patient, he can be hard to get answers from, but he knows his tranny stuff.
 

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I don't try to be hard to get answers from.....


Does the truck have a chip or a tuner?
 

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With the transmission warmed up, in park, and the engine idling, what is the trans fluid level? Does it have a burnt odor to it? What color is the fluid, red, pink, brown, or black?
 

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The stock 4R100 in my 2000 7.3 had a weird kind of shift when under full throttle for that gear.
Original 4R100 lasted 203k miles, I replaced it with an HD4R100, the odd 2-3 shift under power was gone, so someone figured out how to fix it in the HD version.
 

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I don't know what the problem is. I need more data. You need a tool that can tell what gear the PCM is commanding, and whether it is commanding the torque converter to lock or not.
 

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The stock 4R100 in my 2000 7.3 had a weird kind of shift when under full throttle for that gear.
Original 4R100 lasted 203k miles, I replaced it with an HD4R100, the odd 2-3 shift under power was gone, so someone figured out how to fix it in the HD version.

John Wood figured that out along time ago. I have a stock tranny, and put Johns throttle body on there. Its still holding together, and I toss all my torque at it all the time. Before I got my low bed and rig, I used to tow my 26000 lb backhoe with my truck, and boy did that throttle body work great. I probably have 50 000 miles on it since I exceeded 500hp, still holding together. lol
 

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Discussion Starter #16
Thanks guys. Sorry I couldn't give a better description of the problem. Just one more question. Does engine oil level have anything to do with transmission performance? I was reading some of the earlier posts about transmissions and came up on one that mentioned that it did. Anyway, I did notice my oil level was low, so I changed the oil and seems like it's shifting much better? Crazy or what, lol?
 

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The stock 4R100 in my 2000 7.3 had a weird kind of shift when under full throttle for that gear.
Original 4R100 lasted 203k miles, I replaced it with an HD4R100, the odd 2-3 shift under power was gone, so someone figured out how to fix it in the HD version.

John Wood figured that out along time ago. I have a stock tranny, and put Johns throttle body on there. Its still holding together, and I toss all my torque at it all the time. Before I got my low bed and rig, I used to tow my 26000 lb backhoe with my truck, and boy did that throttle body work great. I probably have 50 000 miles on it since I exceeded 500hp, still holding together. lol
Absolute, I have looked at the John Wood valve bodies on Strictly Diesel. For our trucks with a tuner, and everything else being stock, are you saying it will lead to additional longevity of the 4R100? I don’t have any complaints with my truck but will be towing something heavier than a fishing boat in the near future. TIA
 

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Valve body, not throttle body. Transmissions do not have throttle bodies.
 

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Hahaha, yup, valve body, my typo. Oops. But yes, I totally believe that VALVE BODY made a massive difference in the longevity of my transmission. It also made massive improvments in shifting across the board with all my tunes. Towing included. I think it was around 200 bucks when I bought it, well worth the dollars. Wish I could afford the transmission he makes as well. Being in Canada, by the time I cover shipping and core return, exchange, duty etc etc, I'm looking at about 10k for it. Want it , just cant buck up that much right now. I'd prefer to do a standard conversion. Had an entire kit lined up, with everything I needed, procrastinated, and at 1500 for the whole works some one else scooped it up before I was done humming and hawing. Haven't seen one since. Any one have a tissue.
 

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Discussion Starter #20
Okay, update on my shifting issue. Like I mentioned originally, we just recently purchased the Excursion when we noticed the strange shift from second to third gear. Along with checking things out, I noticed the oil level was low and looked like it was way overdue for an oil change. So I changed the oil and surprisingly it seems as if the strange shift has gone away. The only thing I notice now is that it seems to stay in second longer than it should and that hard acceleration sometimes causes a hard shift. With lower acceleration the shift is normal. Even pulling my 8k pound camper the shifts are smooth. So I guess my question would be does the engine oil level affect the transmission in any way and is the extended time in second gear sound like a possible issue?
 
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