New Transmission shifting

04Trailblazer

Original poster
Member
Feb 27, 2012
53
So about 2 months ago my Transmission went out on a road trip It hat 165,000 miles on it, I had some clutch packs burn up on me and was building up heat way to fast and was done for, So I had it towed to a shop and had them put a brand new Transmission in it instead of rebuilding my old one, I got a 3 year/ 100,000 mile warranty with GM. Anyways, I notice with my new transmission that 1st gear going into 2nd is kinda a rough shift and sometimes slips or revs up into 2nd, but 2nd to 3rd and 4th are all smooth as butter and cant even tell it shifts. Just wondering, did my new transmission need tuned to my PCM? I even asked the shop if they had programmed it or if it even needed programmed, He told me no, that it shouldnt be a problem. Just kinda irritates me I spent $2500 with labor for a new tranny that jolts into 2nd gear, I also notice that sometimes if i give it a lot of gas from 1st to 2nd it shifts smooth, but if i dont give it very much throttle it kinda just shifts roughly into 2nd. Any Idea's? I really appreciate it guys! Thanks, Alec
 

lairdt

Member
Dec 12, 2012
15
04Trailblazer said:
So about 2 months ago my Transmission went out on a road trip It hat 165,000 miles on it, I had some clutch packs burn up on me and was building up heat way to fast and was done for, So I had it towed to a shop and had them put a brand new Transmission in it instead of rebuilding my old one, I got a 3 year/ 100,000 mile warranty with GM. Anyways, I notice with my new transmission that 1st gear going into 2nd is kinda a rough shift and sometimes slips or revs up into 2nd, but 2nd to 3rd and 4th are all smooth as butter and cant even tell it shifts. Just wondering, did my new transmission need tuned to my PCM? I even asked the shop if they had programmed it or if it even needed programmed, He told me no, that it shouldnt be a problem. Just kinda irritates me I spent $2500 with labor for a new tranny that jolts into 2nd gear, I also notice that sometimes if i give it a lot of gas from 1st to 2nd it shifts smooth, but if i dont give it very much throttle it kinda just shifts roughly into 2nd. Any Idea's? I really appreciate it guys! Thanks, Alec

In December I got the same transmission, 3yr/100k... they adjusted the shift points in my PCM and put 40+ miles on it road testing. It shift just like any stock transmission I've even driven... soft and either too early or way too late. But, they did adjust the shift points.
 

seanpooh

Member
Jan 24, 2012
461
A member (rodie) might chime in on how the PCM works. Even though if you have a stock or tuned PCM, it will adjusts it's own shifting time ever so slightly to compensate for other variables such as fuel trim and how dirty the TB is and what not.

Since they replaced the tranny, I assume they didn't disconnect your battery for more than 30 minutes for the PCM to reset. If they did, then you would have a dirty TB which the PCM thinks is clean.

Furthermore, since it is a crate tranny, reseting the PCM will be perfect since it's factory settings.

I guess what I am suggesting is, disconnect the battery long enough for the PCM to reset and if you could clean the TB. Drive to see if there is a change.
 

04Trailblazer

Original poster
Member
Feb 27, 2012
53
seanpooh said:
A member (rodie) might chime in on how the PCM works. Even though if you have a stock or tuned PCM, it will adjusts it's own shifting time ever so slightly to compensate for other variables such as fuel trim and how dirty the TB is and what not.

Since they replaced the tranny, I assume they didn't disconnect your battery for more than 30 minutes for the PCM to reset. If they did, then you would have a dirty TB which the PCM thinks is clean.

Furthermore, since it is a crate tranny, reseting the PCM will be perfect since it's factory settings.

I guess what I am suggesting is, disconnect the battery long enough for the PCM to reset and if you could clean the TB. Drive to see if there is a change.

Alright Thanks guys! I will give it a shoot and unhook my battery for a full 30mins and let it relearn its self, Ive got a very clean Throttle body ;D
 

04Trailblazer

Original poster
Member
Feb 27, 2012
53
seanpooh said:
Any new updates on the tranny shifting?

Well, i unhooked the battery for 30 mins, and hooked it back up. started it up and drove it around for a good 15 mins or so just letting it shift, Couldn't really tell a difference it still continued to shift pretty firm from 1st to 2nd gear, My mom finally mentioned the other day that she left 4hi on while driving on dry pavement from the house to her work witch is about 10 - 15 miles. I wonder if her leaving it in 4Hi on dry pavement while driving had any thing to do with it, she did mention she heard some noises but she wasn't sure what kind of noises... The mistakes my mom makes :duh: I personally haven't driven it in about 4 days since i hooked the battery up, so im not sure how it's shifting now.
 

Lima Tango

Member
Dec 4, 2011
242
My factory trans acts the exact same way ever since I got a PCM tune. Not sure if that's pure coincidence or matters to you at all, but hey, at least you know you're not alone in the weird 1-2 shifting transmission universe.

BTW - whereabouts in Idaho are you? I grew up in Boise.
 

04Trailblazer

Original poster
Member
Feb 27, 2012
53
Lima Tango said:
My factory trans acts the exact same way ever since I got a PCM tune. Not sure if that's pure coincidence or matters to you at all, but hey, at least you know you're not alone in the weird 1-2 shifting transmission universe.

BTW - whereabouts in Idaho are you? I grew up in Boise.

Well, Took it out for a drive tonight and it's shifting a little smoother, so unhooking the battery must of helped some... I'm from Caldwell, Idaho.
 

CaptainXL

Member
Dec 4, 2011
2,445
Check the thermostat to see if its failing or failed. A firm shift from 1st to 2nd and sometimes being accompanied with a code P0128 will produce a firm shift.
 

04Trailblazer

Original poster
Member
Feb 27, 2012
53
CaptainXL said:
Check the thermostat to see if its failing or failed. A firm shift from 1st to 2nd and sometimes being accompanied with a code P0128 will produce a firm shift.

Thanks, I replaced my thermostat about a year ago, Id hate to change it out again :hissyfit: haha. but il check it out.
 

Sparky

Member
Dec 4, 2011
12,927
When cold my 02 hangs onto 1st for a little longer than normal then bumps into 2nd. It's a little odd, but it has always done that since I got it 60k miles ago (now at almost 172k), and it is on the first time or two it does the 1-2 shift. Does yours do it always whether cold or warm?
 

04Trailblazer

Original poster
Member
Feb 27, 2012
53
Sparky said:
When cold my 02 hangs onto 1st for a little longer than normal then bumps into 2nd. It's a little odd, but it has always done that since I got it 60k miles ago (now at almost 172k), and it is on the first time or two it does the 1-2 shift. Does yours do it always whether cold or warm?

It seems to be shifting smoother. :smile: whoo! And it's only shifting firmly into 1st to 2nd during cold start and drive. but one fully warmed up it's not as rough of a shift.
 

CaptainXL

Member
Dec 4, 2011
2,445
A firm shift when the engine is cold could also be the coolant temp sensor. The coolant temp plays an almost exclusive part in how the transmission shifts.

I would get a scan tool and check to see that outside ambient temps match what the coolant temp sensor is telling the pcm. Just to rule out thecoolant temp as a cause. This is really the only thing I can think of that would cause a firm shift only when cold. Other than that I suppose the transmission filter could be stopped up a bit.
 

trailblazin06

Member
Jan 6, 2013
29
CaptainXL said:
A firm shift when the engine is cold could also be the coolant temp sensor. The coolant temp plays an almost exclusive part in how the transmission shifts.

I would get a scan tool and check to see that outside ambient temps match what the coolant temp sensor is telling the pcm. Just to rule out thecoolant temp as a cause. This is really the only thing I can think of that would cause a firm shift only when cold. Other than that I suppose the transmission filter could be stopped up a bit.

can you think of anything that would cause it when it cold and warm but does not shift hard when you get on it
 

Mypetropig

Member
Dec 29, 2011
226
trailblazin06 said:
can you think of anything that would cause it when it cold and warm but does not shift hard when you get on it

Torque management? Try a bottle of Lube Gaurd Red, you cam get it at most parts stores or online.:twocents:
 

trailblazin06

Member
Jan 6, 2013
29
Mypetropig said:
Torque management? Try a bottle of Lube Gaurd Red, you cam get it at most parts stores or online.:twocents:

where do you put it in? and do you have to release any other fluid before using this product.
 

Mypetropig

Member
Dec 29, 2011
226
Its added through the fill tube, same tube that holds the dipstick. Mine was just a tad low after a pan drop and filter change so I was able to top it off with that. If your tranny is completely full then I would suspect you would have to remove some. That can be done through the same tube with a hand held siphon pump, which is also available at most parts stores.

Lubegard 60902 Automatic Transmission Fluid Protectant : Amazon.com : Automotive

http://www.amazon.com/dp/B0043YIFGU/?tag=gmtnation-20
 

CaptainXL

Member
Dec 4, 2011
2,445
trailblazin06 said:
can you think of anything that would cause it when it cold and warm but does not shift hard when you get on it

Throttle body might need to be cleaned and the pcm reset by pulling it's fuse for 30 minutes.

Low fluid level can be a cause as well. Check the level with engine fully warmed up in park while idling engine. Make sure truck is on a level surface.
 

seanpooh

Member
Jan 24, 2012
461
CaptainXL said:
I would get a scan tool and check to see that outside ambient temps match what the coolant temp sensor is telling the pcm.

Does the ambient temperature sensor (located at the front top of grille) play a role in the fuel, ignition and transmission shifting? I thought it was only used to show the temp outside to you on the inside...
 

CaptainXL

Member
Dec 4, 2011
2,445
seanpooh said:
Does the ambient temperature sensor (located at the front top of grille) play a role in the fuel, ignition and transmission shifting? I thought it was only used to show the temp outside to you on the inside...

No, the pcm only uses the coolant temp sensor. You want to check the temp using a scan tool when the engine is completely cool to see if it is reporting the same temp as the outside air temp. For instance a cts that said the coolant was 150 degrees F on a cold 32 degree F morning would obviously mean that it is not reporting the correct temp to the pcm. In this case the engine would run too lean. Conversely if the cts reported a colder temp than what the coolant actually was then the engine would run too rich.
 

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