4l80e acting strange after shift kit install
Thread Starter
Teching In
Joined: Feb 2018
Posts: 22
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From: Billings, MT
4l80e acting strange after shift kit install Hi all,
Another hobbyist here who messed up a shift kit install. Strange right? Anyways, I just installed a Transgo HD2 shift kit into my 2003 silverado and noticed 2 strange behaviors after the install. When the truck is cold it doesnt seem to want to engage 1st gear until I give it a bit of throttle. (Time 7:02:49 in log) The other issue is that when downshifting to first (like when coming up to a stop sign) when it engages 1st the engine boggs down for a second. (Time 7:03:27 in log) The transmission seems to be acting fine other than that. Shifts into all gears nicely. Park through 1st all seem to act like they should. Its just the strange 1st gear behavior. I will provide some details on the install, current tune, and a log showing the issue. The log shows line pressure but I'm unsure what is normal and what isnt.
Install
1. I installed only the portions that I could while the transmission was in the truck.
2. I skipped the steps that pertained to the pressure relief mod based on a suggestion from Jake in another thread.
3. I skipped step 9 that reduces servo travel, again based on comments that Jake had made another thread.
4. I drilled the transgo plate to 0.086" on all three holes.
5. I used just the outer spring on the accumulator because I wanted a bit of extra firmness.
Other than that the transmission seems to be working ok. Do you guys have any ideas on what could be going on? I bit off more that I could chew with this mod and I have a lot more respect for people who are experts in transmission work now. Thanks guys.
Another hobbyist here who messed up a shift kit install. Strange right? Anyways, I just installed a Transgo HD2 shift kit into my 2003 silverado and noticed 2 strange behaviors after the install. When the truck is cold it doesnt seem to want to engage 1st gear until I give it a bit of throttle. (Time 7:02:49 in log) The other issue is that when downshifting to first (like when coming up to a stop sign) when it engages 1st the engine boggs down for a second. (Time 7:03:27 in log) The transmission seems to be acting fine other than that. Shifts into all gears nicely. Park through 1st all seem to act like they should. Its just the strange 1st gear behavior. I will provide some details on the install, current tune, and a log showing the issue. The log shows line pressure but I'm unsure what is normal and what isnt.
Install
1. I installed only the portions that I could while the transmission was in the truck.
2. I skipped the steps that pertained to the pressure relief mod based on a suggestion from Jake in another thread.
3. I skipped step 9 that reduces servo travel, again based on comments that Jake had made another thread.
4. I drilled the transgo plate to 0.086" on all three holes.
5. I used just the outer spring on the accumulator because I wanted a bit of extra firmness.
Other than that the transmission seems to be working ok. Do you guys have any ideas on what could be going on? I bit off more that I could chew with this mod and I have a lot more respect for people who are experts in transmission work now. Thanks guys.
TECH Junkie
Joined: Dec 2012
Posts: 3,618
Likes: 1,328
From: Iowa
Skipping the pressure relief mod is a good idea. And it will not hurt anything, despite what the comments above say.
It causes more harm than good, and when it fails (most of them usually do...the ball and spring design is junk) you smoke the entire trans in a jiffy. Skipping the pressure relief was a good idea.
The servo travel limiter is fine to leave out. Won't hurt a thing.
Now to your problems.
is 1st lazy to engage only on the first time you go to that gear in each trip...or is it lazy each and every time. Like even if you've driven 10 miles from your garage to the hardware store, you leave the car running, then put it in 1st from park...is it still lazy?
First shift of a trip issues are fairly common in 4l80e's with converter drainback issues
As for the bogging, check your tune. Lots of guys mess up the TCC tables, it's not uncommon at all. I'm at work so I can't open your tune file...but check it out.
It causes more harm than good, and when it fails (most of them usually do...the ball and spring design is junk) you smoke the entire trans in a jiffy. Skipping the pressure relief was a good idea.
The servo travel limiter is fine to leave out. Won't hurt a thing.
Now to your problems.
is 1st lazy to engage only on the first time you go to that gear in each trip...or is it lazy each and every time. Like even if you've driven 10 miles from your garage to the hardware store, you leave the car running, then put it in 1st from park...is it still lazy?
First shift of a trip issues are fairly common in 4l80e's with converter drainback issues
As for the bogging, check your tune. Lots of guys mess up the TCC tables, it's not uncommon at all. I'm at work so I can't open your tune file...but check it out.
Thread Starter
Teching In
Joined: Feb 2018
Posts: 22
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From: Billings, MT
Well my buddy and I took everything apart and and double checked everything and then checked again. As far as we can tell, everything looks fine as it is installed. Checkballs in correct positions, all caps and o-ring plugs are seated correctly. The boost valve is seated all the way in the pump and the c-clip is securely in its groove. We started it up and are having the same issues. The lazy engagements are happening most of the time.
We did check the line pressures this time though and its not looking good. Pressure in P/N jump to 130ish right when the truck starts and then drops to around 40psi at idle. At stall it goes to around 70. All gears including reverse are 30 or below. I didn't want to strain the clutches on such low pressure so I didn't check if the pressure rose much with throttle. Same resultes with the harness unplugged. I decided not to drive it after seeing the extremely low pressures. I don't know what is wrong and I don't know what to troubleshoot at this point. I am going to call transgo on monday and see what they say.
Also, I scanned for codes and there were none. I did reset them after pulling the harness.
Please see attached log from today after teardown.
Do you guys have any ideas?
We did check the line pressures this time though and its not looking good. Pressure in P/N jump to 130ish right when the truck starts and then drops to around 40psi at idle. At stall it goes to around 70. All gears including reverse are 30 or below. I didn't want to strain the clutches on such low pressure so I didn't check if the pressure rose much with throttle. Same resultes with the harness unplugged. I decided not to drive it after seeing the extremely low pressures. I don't know what is wrong and I don't know what to troubleshoot at this point. I am going to call transgo on monday and see what they say.
Also, I scanned for codes and there were none. I did reset them after pulling the harness.
Please see attached log from today after teardown.
Do you guys have any ideas?
Last edited by lanebaumann; Jul 8, 2018 at 12:24 AM. Reason: Add log and engine code info
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TECH Junkie
Joined: Dec 2012
Posts: 3,618
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From: Iowa
The problem with all shift kits, is people have no idea what they do. Or worse, they THINK they know what a shift kit does and that is even more dangerous sometimes.
If I'm building a unit, I refuse to use an HD2 kit. Half of the parts of an hd2 I leave out, 1/4 of them there are better parts out there for, and the other 1/4 you can do internally and have less cost and better results.
For someone that just wants to drop the pan, slap it in, and go...the HD2 is fine but I would still leave half the parts out.
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Teching In
Joined: Feb 2018
Posts: 22
Likes: 0
From: Billings, MT
Another update guys. Called Transgo tech support and got some insight. Sounds like my Actuator Limit Valve may have given up on me. Given the state my transmission was in before and the parts I did install, he said that was the first place to look. He did mention that a PR Valve falling out of place could cause issues as well. My friend and I double, triple, and quadruple checked that it was seated right and did not move when you actuated the valve. I may be taking my truck to a transmission shop so that someone with more knowledge can take a look at the valve body and see if anything is wrong.
TECH Junkie
Joined: Dec 2012
Posts: 3,618
Likes: 1,328
From: Iowa
48-ACT-TL is the transgo kit. I'm surprised they didn't offer it as the remedy when talking with them.
I have a thread on how to vacuum test a valve body and build your own stand to do it.
Hate to see you have to go to a shop, but if this is out of your wheelhouse, then be sure to take it somewhere that will vacuum test the VB, ream the bore and fit new valve, then vacuum test again to confirm the problem is fixed.
I have a thread on how to vacuum test a valve body and build your own stand to do it.
Hate to see you have to go to a shop, but if this is out of your wheelhouse, then be sure to take it somewhere that will vacuum test the VB, ream the bore and fit new valve, then vacuum test again to confirm the problem is fixed.
Thread Starter
Teching In
Joined: Feb 2018
Posts: 22
Likes: 0
From: Billings, MT
48-ACT-TL is the transgo kit. I'm surprised they didn't offer it as the remedy when talking with them.
I have a thread on how to vacuum test a valve body and build your own stand to do it.
Hate to see you have to go to a shop, but if this is out of your wheelhouse, then be sure to take it somewhere that will vacuum test the VB, ream the bore and fit new valve, then vacuum test again to confirm the problem is fixed.
I have a thread on how to vacuum test a valve body and build your own stand to do it.
Hate to see you have to go to a shop, but if this is out of your wheelhouse, then be sure to take it somewhere that will vacuum test the VB, ream the bore and fit new valve, then vacuum test again to confirm the problem is fixed.
I would feel confident performing the work to fix the actuator valve but at this point, everything is a shot in the dark. I have taken apart and re-assembled everything 3 times now (On a 2003 silverado 4x4 which takes me about 5-6 hours each time) I am getting a little discouraged at my attempts to remedy the problem I am having and I feel like I am in over my head.
I will call around to transmission shops and see what they think.
On The Tree
Joined: Jun 2010
Posts: 120
Likes: 2
I forgot to mention that he did recommend that exact kit.
I would feel confident performing the work to fix the actuator valve but at this point, everything is a shot in the dark. I have taken apart and re-assembled everything 3 times now (On a 2003 silverado 4x4 which takes me about 5-6 hours each time) I am getting a little discouraged at my attempts to remedy the problem I am having and I feel like I am in over my head.
I will call around to transmission shops and see what they think.
I would feel confident performing the work to fix the actuator valve but at this point, everything is a shot in the dark. I have taken apart and re-assembled everything 3 times now (On a 2003 silverado 4x4 which takes me about 5-6 hours each time) I am getting a little discouraged at my attempts to remedy the problem I am having and I feel like I am in over my head.
I will call around to transmission shops and see what they think.
Thread Starter
Teching In
Joined: Feb 2018
Posts: 22
Likes: 0
From: Billings, MT
Embarrassingly enough, I did not have enough fluid in the transmission. I still don't know how to get a truly accurate reading on fluid level. Hot? Cold? Running? Not running? There area a million different answers and to top it all off, every time I take a reading it is skewed by the fluid that is scaped off of the dipstick tube. So long story short, I just dumped in a couple extra quarts of ATF and it works now.
I have a quirky behavior that I believe can be remedied by the Sonnax line to lube PR valve though.
I have a quirky behavior that I believe can be remedied by the Sonnax line to lube PR valve though.