4l60e First gear problems

[Gerbil21]

OK well this is my first post and yes I did search but it's hard to search for this problem specifically.

ok well there is alot to say so ill try to break it into sections

now for some info:
05 GMC Envoy 4.2 i6 4x4 with 141k
As far as I can tell the trans is original (no markings on valve body)

OK now to explain the problem (also the dipstick never wiped clean it always has a black stain with it on the napkin)

starting from when i bought the car at 133k the dealer replaced the trans fluid

The 1-2 shift was very delayed and harsh, it felt like it was slipping bad also i could never let go of the gas or give less gas during the shift to help since it would just hang between shifts and when it did engage it was very harsh. the rest of the gears were fine.

because of this we decided to do a flush by connecting the output to a hose a letting the car run no chemicals used, we also did a filter change and replaced both shift solenoids (thinking it may help). the pan magnet was pretty dirty, the fluid was dark and bad smelling but not much burnt smelling just old. And that did nothing at all to help the shifts


now we move onto the shift kit install about 2k miles later: ctpowertrain kit (transgo shift kit, corvette servo, and new v.b. separator plate & gaskets, pinless accumulator pistons,nylon screens and I also got new torlon check balls)

we dropped the pan and saved the fluid, cleaned the somewhat dirty magnet and removed the valve body and accumulator pistons (they were not stuck in bore, and they seemed to not have any wear on the pin bore and the seals were good) there were about 3 checkballs stuck in the plate. both the gaskets and plate were worn and there were signs of leaks from the gaskets. we then installed everything and it had a better shift time with not as much delay but sometimes almost the same as before. but what did change was a very harsh 1-2 shift almost always no matter what unless i was feathering the throttle. All other gears were good and it felt like it had a shift kit and was working good except for that one gear. also lock up was like going in a gear and felt very good.

also this is the point where i first noticed another problem, im not shure if it was there already but when i put it in manual first it dosent roll, and if i give it gas the whole car will shudder. this happens almost all the time but sometimes not, when it dosent it drives fine and the shift from 1-2 is the same as in drive. also idk if it means anything or my app was wrong but once when i went into first and it shuddered i noticed the scanner said it was in 2nd gear, at another light i did it again and it said 1rst gear and that time it worked fine. So is it holding two gears???

now we get to where i install the servo - about another 2k miles later (and how it sits now)
it was a pain in the ass but i got it in and the first drive felt good but then it went back to bad shifting, the shifts at this point are the best so far, the delay isnt much and the shift isnt all that harsh but still is a hard shift (just so you understand the scale of how im rating harshness when it shifts you feel it in the car as a bump and it dosent feel firm and progressive)
the shifts can be changed even thought, every start up the shifts are different, sometimes a hard shift sometimes smooth shifts sometimes it feels like a good shift kit, it depends on the pedal (never wot) at light throttle it shifts good and after a while it will shift as if light throttle but when giving moderate throttle, if just moderate its a bit more of a bump, if i drive aggressive it can hit hard sometimes or drive perfect with good firm shifts, i usually drive in 3rd because im in nyc and in drive it can hunt for gears sometimes when i coast and then have to give gas which can be frequent. but they both act the same. usually 3rd gives it a bit more consistent firm shifts and drive gives sometimes soft and sometimes a bit slower hard shifts. and i have noticed when in drive with its gear hunting sometimes if i need more speed and i just slowed down it shifts into gear harsh and i can hear a metal clunk sound.

Edit: Also forgot to say that i get a thump on 2-1 downshift when braking harder than normal

im not shure whats the main problem is and im hopping its something electronic like needing a tune. since its stock pcm with all torque management on

[Gerbil21]

also ill take a pic of fluid color and the stain on a napkin and ill see if i can make a video of the shifts

[pajeff02]

Welcome to the site!

No need to spend time searching (although you are more than welcome to do so). Just ask any question that you have -- we're a friendly bunch here.

Honestly, sounds like a tired transmission that had a hard life before you acquired the truck. The 4L60E isn't exactly a stout unit from the factory. This being said, like any transmission, heat and lack of maintenance will kill them. When you drop the pan to change the fluid, you may get half or a little more of the fluid out. Flushing it by running the transmission with a cooler line disconnected is one method of replacing more of the fluid volume. I trust that someone was dumping fluid in as it was coming out?

I think your valve body and other modifications probably band aided the issue a bit, but she probably needs gone through. If you do a rebuild, there are certain parts that should be upgraded, including the sunshell and front pump. We have some real gurus on here, I'll see if I can chase one over to take a look at this thread to see what they think.

[Gerbil21]

Thanks for the great welcome and for getting more help makes me like this site a bunch more!

also no at first i only drained stropping when it "burped" some air, after the filter change i filled and drained until clean.

i should be doing another flush soon is there anything you recommend doing while there? adatives? i will be checking all solenoid voltages and screens for debris

also i was thinking of adding a Trans cooler, any recommendations? Trans temp was 200* on a 80* day after 1 hour of constant highway at 80mph then 60mph and then 60-70mph with a few stoplights in between. temp was checked after getting off highway

[Firebirdjones]

I read through that, hard to follow, but I'm not sure if I caught anything about the 1-2 accumulator.

Usually when the 4L60 starts having 1-2 shift problems, especially shudder, the accumulator is worn. If you can pull the accumulator out and flip it up side down and the piston/pin assembly falls out.....it's worn. Sometimes you'll see wear on the walls, scuffing etc...

If you've already replaced/rebuilt the accumulator, you could always try the 1-2 shift solenoid, that's a cheap and easy swap, they are only $15.

Another simple check would be the TPS on the throttle body. If that's reading funky it causes odd shift problems, delayed, harsh etc..because the trans tables use the TPS to determine pressure and likely a couple other tables that get complicated.

Those are the simple things. However with mention of your fluid being brown or dark, this trans might be beyond the simple fixes and could be time for a refresh.

[pajeff02]

Trans cooler is always a good idea. I installed one on our car when the new transmission and 3,200 converter went in a few years ago. I also installed a transmission temperature gauge to keep an eye on things. Sounds like your truck may have the stock trans temp readout option. Our Suburban with the tow package came so equipped and it was a welcome surprise to have it.

[Gerbil21]

Trans cooler is always a good idea. I installed one on our car when the new transmission and 3,200 converter went in a few years ago. I also installed a transmission temperature gauge to keep an eye on things. Sounds like your truck may have the stock trans temp readout option. Our Suburban with the tow package came so equipped and it was a welcome surprise to have it.

Yes i only have the stock in pan temp sensor, when I do get around to installing a cooler I'll make sure to get a temp sensor with it.

I read through that, hard to follow, but I'm not sure if I caught anything about the 1-2 accumulator.

Usually when the 4L60 starts having 1-2 shift problems, especially shudder, the accumulator is worn. If you can pull the accumulator out and flip it up side down and the piston/pin assembly falls out.....it's worn. Sometimes you'll see wear on the walls, scuffing etc...

If you've already replaced/rebuilt the accumulator, you could always try the 1-2 shift solenoid, that's a cheap and easy swap, they are only $15.

Another simple check would be the TPS on the throttle body. If that's reading funky it causes odd shift problems, delayed, harsh etc..because the trans tables use the TPS to determine pressure and likely a couple other tables that get complicated.

Those are the simple things. However with mention of your fluid being brown or dark, this trans might be beyond the simple fixes and could be time for a refresh.

Yes sorry about it not being easy to read, I was trying to cram as much info in. Also yes I replaced the 1-2 accumulator and the forward accumulator with sonnax pinless aluminum pistons, the stock pistons looked good they were not stuck sideways, they moved with some resistance and grip on their housing, and the seals were good aswell were the pins and there bores they didn't have play in them. I dont think I remember checking to see if they fall out but I'll go check.

I have replaced both shift solenoids, and I have a extra throttle body that I was going to swap in today, these trucks have drive by wire tb's so the TPS shouldn't go bad as easily since there sealed in but I'll still swap it in and see.

Also when I do go the rebuild route what should I look for? 4l65e sunshell, raybesto gpz105, 3-4 servo? Any other upgrades? I would like to have a quick firm progresive feeling shift. Aswell as turn off all torque management

[Firebirdjones]

No need to appologize, I actually enjoyed all the information. Most questions are too vague and not enough info provided.

Sounds like you have it covered. I didn't realize you were drive-by-wire. Probably won't fix the issue but if you have a spare to swap it wouldn't hurt to try.

[Gerbil21]

No need to appologize, I actually enjoyed all the information. Most questions are too vague and not enough info provided.

Sounds like you have it covered. I didn't realize you were drive-by-wire. Probably won't fix the issue but if you have a spare to swap it wouldn't hurt to try.

Well it's been past a year since my op but it's still alive! Haha

Either way I still have this 1-2 shift issue, Replacing the throttle body actually made a big difference even thought and once I changed it the shift was timed much better and the shift dropped out of the harsh range.

I have 149k now and a tuned pcm, the shifts are still firm, sometimes a tad harsh, but most of the time they still have a delay which causes the shift to feel wrongly timed and have a overall negative feel. I have watched the shift a bunch of times and it does happen at the correct speed and throttle input but it doesn't have any positive feel.

Right now it only adds some pressure during the 1-2, and for the 2-3 shift never more then 6psi. For the 1-2 shift tap cells 4&5 get -3.98psi, T.C. 6 is +4.98psi, and T.C. 7 is +0.75psi. The shift times have a low of 0.2 and a high of 0.3 seconds under most conditions, The shift error brings either a 0 or 0.1 on a 0.2 shift and -0 on a 0.3 timed shift

From the data logging I've done it dosent seem to actually have much straight line slip, I've only seen it go to 38% duty cycle on the PC solenoid once, that was while it was at 42% throttle in 2nd gear and in tap cell 4 at 24mph

Now, I can actually fix all my shifting problems by pulling pcm fuses and the TCM fuse, after this with the tap cell history cleared it shifts perfectly! Nice and quick smooth transitions through the gears and it's perfectly timed and best of all the shift feels amazingly positive, the car accelerates much better because of the smooth 1-2 positive shift.

but unfortunately all good things come to an end, eventually the shifts will go right back to being delayed and firm and the car feels so sluggish.

I was going to replace the tmps ("Transmission Manual Valve Position Pressure Switch") since everything seems to tie it directly to the manual first gear shudder, but I don't see if it can actually help the regular shifts, if so what else can I check while i have the pan dropped?

And can someone explain my delayed shifts, and why clearing the tap cells makes a huge difference and most importantly if anyone can identify why it goes back to its un-positive shifts.

[Gerbil21]

Here are all the logs I've taken ranging from engine data to trans logs

https://www.dropbox.com/sh/4aewcvb2u...rbg0RG6ta?dl=0