Automatic Transmission - My $350 4L80E was too good to be true! Jumpy + Scrapy/Howl in 1st?!?

I just finished up my car about a month or so ago enough to drive it around. I bought my transmission for $350 locally for a guy who assured me it's in perfect working condition. Turns out its jumping in first! I will be pressing the throttle and the car wont move then all of a sudden it with jump - this goes for 1st gear and reverse(going slow?). It it do it multiple times moving just 10 feet or so. It will even jump at stop lights when the lights turn green and I ease on the throttle. Along with that it's making a odd grimy howl/whistle noise in just first. If I switch into second... It goes away.

Does anyone know what this could be? I've ruled out the brakes and I'm thinking it can't be the rearend due to when I switch into second the noise stops.

To make matters worse, my car is my daily driver :/

Also it was working "fine" for the last week or two. But I did notice the weird first gear noise faintly from the first day I drive it - was just a little light howl at that point.

FWIW-I started a similiar thread. Everyone told me it was convertor. We put in a brand new convertor and mine still does the same thing. I think it is the front pump. Somehow it is not building enough pressure or just has gone bad. In low gear and reverse I have to rev the throttle just a little and it "kicks" into gear. Once I am driving it in 2nd or drive the car is fine. I think bad front pump but still waiting on a definitive answer.

FWIW-I started a similiar thread. Everyone told me it was convertor. We put in a brand new convertor and mine still does the same thing. I think it is the front pump. Somehow it is not building enough pressure or just has gone bad. In low gear and reverse I have to rev the throttle just a little and it "kicks" into gear. Once I am driving it in 2nd or drive the car is fine. I think bad front pump but still waiting on a definitive answer.

thank you for the reply, what are your symptoms originally and currently? and is the vehicle working just "fine" or has it gotten worse and worse?

4L80Es howl in low gear some (you should hear my straight cuts, LOL).

What would you guys recommend for me to diagnose/fix the issue at hand? Should I pay for a rebuild?? I was told the trans has 90,000 miles on it at purchase from a fleet express van. Could it be the tq converter?

It "could" be a converter or pump issue but I think it sounds more like a problem with the low roller clutch. It will need to be completely torn down to address that.

It "could" be a converter or pump issue but I think it sounds more like a problem with the low roller clutch. It will need to be completely torn down to address that.

as weird as this sounds, the problem was virtually gone today as i drove my vehicle - how can this be(other than the howl)? could my tps sensor have anything to do with the jerky 1st and reverse? vss?

well, i dont know if it is a factor but it seems as if my tps his having problem (from what i can tell with a multimeter)

so i have 3 pins on my sensor like this:

____[1]____
__[2]_[3]__

settings my multimeter to 20K Ohms

testing between 2 and 3 i get a constant 4.32

testing between 1 and 3 i get nothing ("1_.__")

testing between 1 and 2 i get various results:

at random positions it gives nothing ("1_.__")

sometimes when set to the lowest position i get nothing and other times i get 1.13

at the highest turned position i get nothing and if i shake the sensor until i get a reading(or push/pull on the "dial") it will be about 5.97-6.30 to even 8.67 sometimes

it seems like the sensor has been replace with a "cts" brand sensor in the past, doesnt say ac delco, delphi, etc. just "CTS" and a odd part number(23852 - E00920)