Inconsistent shifting

Back woods

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Have a 2000 Excursion with 242k miles. Has the basic modifications but no tuner. Truck is an automatic and seems to be strong, fluid looks great. Have owned the truck for 2 years and it has always shifted kind of funny.

Driving nice and easy it will slam into gear. 1-2 is usually rough and sometimes 2-3. Only happens when driving slow. When I step on it 1/2 throttle or more it shifts smooth as butter every time. Have towed all over with it and has never thrown a limp code. Don't know if the transmission has ever been opened up or not. Shifts much different than my 2001 and nothing like my E4OD. Any insight would be appreciated.
 

lincolnlocker

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Might have a mechanical shift kit in it.. low power can cause hard shifts like you describe and then with more throttle/power going through it the trans absorbs it more and shifts smooth.

Kinda like my bts in my dually. Its mechanically set to hold and be smooth at 550hp and i am only pushing 450 through it so it shifts very firm and tight. Turn the chip down to low and it will give you whiplash during shifts. Lol

live life full throttle
 

mandkole

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Does it tend to hold in gear or does it upshift on time?

As said, it could have some line riser or valve body mods. With 240k and unknown when it was worked on last, you likely need to have the pan dropped and look around.
 
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lincolnlocker

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Does it tend to hold in gear or does it upshift on time?

As said, it could have some line riser or valve body mods. With 240k and unknown when it was worked on last, you likely need to have the pan dropped and look around.
Yep, this too^^^

live life full throttle
 

Back woods

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Holds gears and downshifts as it should. When you mat it in OD and kick down to 3rd it will shift back into OD kind of rough. From a dead stop the 1-2 shift is firm but doesn't slam like it does when going slow. When I first got the truck it had an SCT tuner. On the higher setting it will chirp the tires on the 1-2 shift when getting on it from a stop. This shyed me away from running a tune as it shifted way different from my 2001 and my OBS with a TS6. Can a broken accumlator spring cause it to run this way? It shifts as good as you would ever want when you roll into the throttle. No shift flair ever and it doesnt lag in between gears. My 2001 has random shift flair and much slower shifts in comparison. After two years of owning the Excursion the ATF is still as clean as it came out of the jug.
 

mandkole

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Are you sure the SCT is uninstalled? The electronic line rise of a tuner on top of a valve body mod could cause all kinds of part/light throttle issues. You should tune the trans with either electric or mechanical but not both.

My accumulator spring failure experience also had delayed shift/ hold in gear to higher rpm in combination with a slam shift behavior.
 

Back woods

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Gave the tuner to a friend of mine and it will only work on another vehicle if mine is put back to stock. Truck has an ATS housing, 6637 and 4" turbo back. Doesn't hold high rpms between the 1-2 shift unless I floor it. Driving slow it will have a slight delay and if you peddle it just right it can really slam. One thing I have read is a bad accumulator spring will shift good when it is cold and get rough when it warms up. It will do the same when cold and then get rough but if I roll into the throttle smooth out.
 

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