My transmission kicks/shudders between 3rd and 4th up shifting and downshifting about 99% of the time. The Tach isn't jumping so I don't think it's slipping. I've done a lot of research and I thought I had it narrowed down to the Neutral Safety/MLP Sensor. However I searched around a bit again today and found an article Here referencing the trans having this issue with dirty fluid. Any thoughts?

If it does need a trans flush, I've heard that a flush can do more damage than good sometimes, The truck has 215k Miles on it, should i be concerned with doing a flush?

---This is my first post, I've been lurking for a couple weeks and you all are awesome. Thanks for any help you can give me.

 

are you sure its not a misfire?

 

Hadn't thought of that as a possibility. A misfire wouldn't happen specifically when the trans is shifting from 3 to 4 or 4 to 3, would it? If that is a possibilty, how would I daignose it?

 

I should specify that at best it's a shudder, at worst it feels like I've driven over a giant pot hole

 

you'd feel it mostly in 3rd or 4th. Most people would describe it as a bucking sensation. Like forward backword bump if that makes sense.

 

No its not like that, it feels as though my transmission is gonna drop, a very distinct thunk goes with it, it's definitely only at the exact time it shifts.
there also isnt a loss of power or anything either

 

You don't need to flush the tranny to get a complete fluid exchange, the 2000 still has a torque converter drain plug. That and a pan drop will get all but about a quart out. The tranny holds 14 quarts total, 5 in the pan and the rest in the TC and valve body and cooler.

A low grade misfire will be most pronounced right after a light throttle shift into OD and the TC locks up - give it just a bit more gas and it will misfire. This happens when you need new spark plugs and/or the coils (if you have COP) are getting weak. It doesn't happen as often with the old coil pack/plug wire system but it's still quite possible.

 

OK, so now I've gone from 100% to 80% that it's the trans. My head is spinning now. When in 4th gear I can throttle and it doesn't kick until I give it enough to downshift or if I keep the throttle the same and it downshifts to get up a hill. would this rule out miss fire?

 

Hmm - let me ask you this - how many miles are on your spark plugs? Do you have COP or coil packs and wires?

 

I just got the Truck so I'm not sure how many miles the plugs have on it. It has COP

 

Park/neutral switch is only used for engine cranking safety.

its possible you have a bad accumulator spring. Any way you could run the truck by a trans shop and have them drive it without digging deep into the trans and see what they think?

 

Sorry for the crazy delay, I moved and didn't have internet for a while...
Ok so I took my truck to The Big Double A transmission shop. They said it wasn't throwing any codes but they think the EPC selonoid is the problem (Btw they only felt the hard kick, not the shudder).. I thought the price was high so i called another shop. they said the problem I was describing was most likely a torque converter shudder, and I would probably need a rebuild of the trans. I researched the heck out of low grade misfires and that seems like a possibility also. I can't throw money at this aimlessly , what are ya'lls thoughts.

 

Can't seem to edit... Thanks to all those who pointed out low grade missfire, I had never even heard of such a thing until you all mentioned it.

How would I diagnose that. The check light came on a couple weeks ago (system too lean, both banks.) I found a vacuum leak and repaired it, reset the check light and it hasn't come on since.

 

Change your spark plugs. Use Motorcraft, no antiseize, torque to 28 ft/lb. Use a small amount of dielectric grease in the COP boots, not on the springs or contacts. That's going to cost you less than 40 bucks if you do the work yourself.

 

I'll give that a shot, thanks!
..is there a way to determin if the ignition coils are functioning properly ? AZ wants $56 a piece for them.