late shifts, guessing its the vacuum?

[YukonRidin23]

well, my truck is slowly getting there. as i had originally thought, stuff would fail on it since it hadnt been on the road for about a year and just rotting away, but its almost done. i was going to get my tranny done up wensday, just a rebuild and its only going to run me 300 for everything. steal of a deal, and just put in the new power steering pump saturday(the charger made it a super pain in the A$$), and i have the new tie rods and ball joints in and a fresh alignment. but now, im exsperiencing these late shifts. i thought it was the tranny at first, because the truck seems to rev up and then shift real late, or i can go to the speeds where it shifts, let off an it will shift fine, but if i dont let off the gas it kinda keeps revving up for a couple seconds. now i still plan on getting the tranny rebuilt, but just while im in there id like to check out anything else that could be causing this. now like i said before, my buddys g-pa owns the largest chevy dealership around baltimore, and he works as a tech, so the lifts, the tools, and everything else i can use. he told me if i can dig up how much boost each vacuum line is making we can check them there, but he's unsure what levels it should be at. so im curious, does anyone here know what i should be getting around of each line? and any other things that cause late shifts?

 

[95TwinTT]

Do you have a 96 or later 4L60e with OBD2? What vacuum lines are you referring to?

 

[YukonRidin23]

i have a 97 with a 4l60e. im not sure, i was told that it was a vacuum line...? im confused and not really sure what to do? it drives fine if i rev it up real quick right before 20 mph.

 

[79powerwagon]

Is your fluid level correct? All automatic transmissions have some kind of "kick-down" device (mopar has a mechanical link, older GM's have a vacuum operated device, newer cars use electronics). Yours may simply be failing, or your simply low on fluid...

 

[YukonRidin23]

yes it is, thats what came to mind first, but then i put a little extra in even, and the problem still persist.

 

[95TwinTT]

The 97 is totally controlled by the OBD2 Computer. It reponds to all of the inputs from the various sensors from throttle position, to manifold pressure, mass air flow sensor, engine rpm's, temperature, etc.

If I were you, I would visit a transmission shop. It may just be a solenoid not functioning properly. It would be good to fix it before any more damage is done. It could cost you a lot more if you wait.

It is not likely to heal itself...

 

[mross]

not to sound like a jerk but,if your buddy works at a chevy dealer they should have a gm factory manual for the truck.it should tell you everything you need to know

 

[YukonRidin23]

alright, thanks. i was told by someone it might be a synchronizer, but i dont really have a clue what that is or how to tell, all they said is you'd have to drop the trans out. if i went and got my trans rebuilt would it just fix the problem? because i need new plates aswell.

 

[Untitled415]

Ok to start synchronizers are only in manual trans so i doubt that could even considered the probelm. I work at a transmission shop and from it sounds like your trans is slippin. The first check i would look at making sure your fluid is full (the most common and simple fix) also as stated above your trans does not run off a modulator (vaccum) it is controlled by the computer and i am not sure what your buddy is referring to unless he is mistaking the truck for a different year. Also when checking the fluid be sure to start the car before checking it. If the fluid is full then its proly the seals inside the trans that have gone bad and a simple rebuild will take care of the problem.

 

[blk97yukon]

I would think the pcm would give some type of p-code. Are you getting any codes at all? Anyhow I agree with the others that you should ck the FL. If that checks out, visit a tranny shop you trust.