Won’t shift at WOT any advice?

[Trey Hardy]

Truck drove great prior to the engine build we did drop the pan and change the filter maybe that had something to do with it drives fine but wide open throttle it free spins right before it shifts it’ll hold first but not second or third wide open I put a vette servo in it and it kinda helped but obviously did not fix it what is next? Pan drop another new filter and maybe new shift solenoids and tcc? Thanks for any advice guys

 

[Trey Hardy]

Shift points are set at 6100
No codes or check engine lights

 

[OR VietVet]

Hopefully @rockola1971 can chime in.

 

[rockola1971]

If transmission worked fine before engine rebuild and never worked correctly since engine was reinstalled then I would suspect program in PCM is setup wrong. Has there been someone in there doing a tune? 2&4 are the only gears that use the 2-4 band.

 

[Trey Hardy]

Anything other then first gear will let loose above 5,000 or so it was set to shift at 6,100 rpm it is tuned but by a reputable tuner it was doing this prior to the new tune when I was running off the previous tune but ran fine prior to the fluid change and motor work note motor was not pulled only heads all work was done in the engine bay tranny fluid is at level im gunna change the fluid again and another new filter but I did not know if it was worth trying silenoid or not

 

[OR VietVet]

Anything other then first gear will let loose above 5,000 or so it was set to shift at 6,100 rpm it is tuned but by a reputable tuner it was doing this prior to the new tune when I was running off the previous tune but ran fine prior to the fluid change and motor work note motor was not pulled only heads all work was done in the engine bay tranny fluid is at level im gunna change the fluid again and another new filter but I did not know if it was worth trying silenoid or not

I really want to know how that is done? By "that", I mean, making a whole sentence out of all that info. My head hurts, but I am old after all.

 

[Fless]

I really want to know how that is done? By "that", I mean, making a whole sentence out of all that info. My head hurts, but I am old after all.

Glad you could fully comprehend it. You're a better man than I.

 

[Trey Hardy]

I was at work sorry
Truck ran fine before I ever Parked it

It was tuned for the Longtubes and exhaust and the mods I had done at the time transmission shifted fine no issue

I changed the pan fluid and filter what time we were doing the head and cam swap

After we got the truck running and driving and somewhat broke in I give it it’s first full throttle but when I got up in the higher rpm range 5,000-5,500 it feels as if the torque converter lets go completely and the truck red lines and will not shift until I let off of the throttle

I thought maybe it was in the tune so I finally met up with my tuner and when he went to drive it the first thing he said was she’s slipping like a MF we done what we could but couldn’t continue because we would’ve blew the tranny

My question is could I have messed something up in the filter change?

Is it worth another fluid and filter change what time I’m in there?

There 3 solenoids in there ones for torque converter clutch is it worth changing these with new ones?

I feel like it’s in the converter more so then the transmission but why would it act up now if it was working perfectly fine a year or so ago before I started building it.

It’s depressing spending over a year building the motor and suspension on this truck finally got it together and now the transmission is acting up…

So any advice would be helpful

Only mods to the transmission was in the tune

I did add a corvette servo hoping it would help with some of the slipping and it did not

Again truck drives for the most part fine but slips like hell on wide open throttles mainly in the higher rpm

Trucks parked once again until I get this issue resolved

 

[randeez]

do you have the tune/ can send it?
and what transmission? 4sp or 6?

 

[rockola1971]

If the tranny was toasted then I would expect it to be slipping aound 2-3k well before 5k. Check filter make sure that it is fully seated into the valve body and has not dropped down into the pan.

 

[Trey Hardy]

do you have the tune/ can send it?
and what transmission? 4sp or 6?

4 speed and no it’s on my buddy’s laptop but was fine the first time he tuned it

 

[Trey Hardy]

If the tranny was toasted then I would expect it to be slipping aound 2-3k well before 5k. Check filter make sure that it is fully seated into the valve body and has not dropped down into the pan.

That’s kinda what I was thinking because the exhaust we couldn’t fully drop the pan and was awkward working on it I guess ima start with the pan and filter I diddnt know if any of those solenoids would cause a issue like this I’ve never had a trans go out on me before

 

[Trey Hardy]

That’s kinda what I was thinking because the exhaust we couldn’t fully drop the pan and was awkward working on it I guess ima start with the pan and filter I diddnt know if any of those solenoids would cause a issue like this I’ve never had a trans go out on me before

My in-law said to change the fluid sounds like there’s not enough pressure getting through to engage it fully and could be something in the filter or the filter might not be on there right

 

[Just Fishing]

There is a high rpm transmission pump spring to prevent pressure loss at higher rpm.

It sort of sounds like it might be related.

In a 700r4 i had to install a shift kit just so it would up shift at wot..

 

[89Suburban]

Sorry Trey good luck my man. Hope it’s not something serious.

 

[Trey Hardy]

There is a high rpm transmission pump spring to prevent pressure loss at higher rpm.

It sort of sounds like it might be related.

In a 700r4 i had to install a shift kit just so it would up shift at wot..

Down shifts fine it’s just once it breaks 5,000-5,500 rpm the TC let’s go and it don’t want to shift like it should until I let off the throttle but definitely can’t get a full “pull” out of it which kind of sucks I drove it to the Christmas party today for all my nephews to see driving normally it acts fine I don’t get it the corvette servo diddnt do much my next guess is to change the pan fluid and filter again debating on doing Servos what time I’m in there also the truck has sat up for two years straight

 

[Trey Hardy]

Sorry Trey good luck my man. Hope it’s not something serious.

Thanks bud hopefully I’ll get it straight after the new years

 

[Trey Hardy]

There is a high rpm transmission pump spring to prevent pressure loss at higher rpm.

It sort of sounds like it might be related.

In a 700r4 i had to install a shift kit just so it would up shift at wot..

Definitely feels like it either looses pressure and don’t have enough to engage the clutch’s or the torque converter is free spinning because it’ll redline if I hold the throttle wide open

 

[Trey Hardy]

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[B-train]

My question is WHY are you so concerned about shifting at WOT 6100 rpm? Do you enjoy working on stuff that much? If it's the vehicle in the first post, you might want to consider a civic or something like that designed to run high rpm. You gain nothing other than premature wear, ****** fuel economy, etc from basing driving off that.

If I'm wrong, and you're a dragstrip oficinado, then I apologize. If you're looking for this to run down public roads and be a nuisance, I don't apologize.

But to get to the question, there are usually torque limiting safeties built into calibrations to prevent this type of abuse. Usually they will cut fuel and force a shift to the next gear, but if you already effed up the trans, that could be your issue. Sounds like you need a built trans and calibration to handle what you are trying to do.