My trans wont shift at WOT
04-11-2010, 05:05 PM
#1
My trans wont shift at WOT I've searched and can't come up with anything definitive. My trans is a built 4L60E... for some reason now it wont shift at WOT in any gear. Any other time, it's good.
Hooked up a pressure gauge, it's a little on the high side of pressure from what GM recommends, but it's within spec.
Hooked up a pressure gauge, it's a little on the high side of pressure from what GM recommends, but it's within spec.
04-12-2010, 02:14 AM
#4
I would not say that without a few test.
1st when the trans is given the command to shift there are only two choices it shifts or it slips if it slipped it would only be a few times till it slipped under all throttle. .
But there are several things to look for
1- The disired shift time could be set to close to the rev limiter I would highly suspect this if when you are slightly off full throttle it does shift. generally at WOT from comand to actual shift depending on the condition of the trans and the rear ratio and of course power level it can take from 200 to 400 rpm to complete the shift on the 1-2 and even more on the 2-3 shift.
And on top of that unless i miss understand this is happening in both the 1-2 and the 2-3 shift an it would seem very unlikley that there would be any mechanical issue affecting both shifts.
There are test you can do to determine if the comand is being given but before i did that I would try lowering the shift points at wot.
I know many times when people are setting up the shift points they fail to take into account that hydraulics unlike electronics are not instant, They also dont take into account converter slip and rate or rpm increase with higher power levels and gearing. this can be particulary true with mail order tunes as they dont have access to the car.
1st when the trans is given the command to shift there are only two choices it shifts or it slips if it slipped it would only be a few times till it slipped under all throttle. .
But there are several things to look for
1- The disired shift time could be set to close to the rev limiter I would highly suspect this if when you are slightly off full throttle it does shift. generally at WOT from comand to actual shift depending on the condition of the trans and the rear ratio and of course power level it can take from 200 to 400 rpm to complete the shift on the 1-2 and even more on the 2-3 shift.
And on top of that unless i miss understand this is happening in both the 1-2 and the 2-3 shift an it would seem very unlikley that there would be any mechanical issue affecting both shifts.
There are test you can do to determine if the comand is being given but before i did that I would try lowering the shift points at wot.
I know many times when people are setting up the shift points they fail to take into account that hydraulics unlike electronics are not instant, They also dont take into account converter slip and rate or rpm increase with higher power levels and gearing. this can be particulary true with mail order tunes as they dont have access to the car.
__________________
04-12-2010, 04:11 AM
#5
I would not say that without a few test.
1st when the trans is given the command to shift there are only two choices it shifts or it slips if it slipped it would only be a few times till it slipped under all throttle. .
But there are several things to look for
1- The disired shift time could be set to close to the rev limiter I would highly suspect this if when you are slightly off full throttle it does shift. generally at WOT from comand to actual shift depending on the condition of the trans and the rear ratio and of course power level it can take from 200 to 400 rpm to complete the shift on the 1-2 and even more on the 2-3 shift.
And on top of that unless i miss understand this is happening in both the 1-2 and the 2-3 shift an it would seem very unlikley that there would be any mechanical issue affecting both shifts.
There are test you can do to determine if the comand is being given but before i did that I would try lowering the shift points at wot.
I know many times when people are setting up the shift points they fail to take into account that hydraulics unlike electronics are not instant, They also dont take into account converter slip and rate or rpm increase with higher power levels and gearing. this can be particulary true with mail order tunes as they dont have access to the car.
1st when the trans is given the command to shift there are only two choices it shifts or it slips if it slipped it would only be a few times till it slipped under all throttle. .
But there are several things to look for
1- The disired shift time could be set to close to the rev limiter I would highly suspect this if when you are slightly off full throttle it does shift. generally at WOT from comand to actual shift depending on the condition of the trans and the rear ratio and of course power level it can take from 200 to 400 rpm to complete the shift on the 1-2 and even more on the 2-3 shift.
And on top of that unless i miss understand this is happening in both the 1-2 and the 2-3 shift an it would seem very unlikley that there would be any mechanical issue affecting both shifts.
There are test you can do to determine if the comand is being given but before i did that I would try lowering the shift points at wot.
I know many times when people are setting up the shift points they fail to take into account that hydraulics unlike electronics are not instant, They also dont take into account converter slip and rate or rpm increase with higher power levels and gearing. this can be particulary true with mail order tunes as they dont have access to the car.
04-12-2010, 10:29 AM
#6
Well if it's got good pressure and a good tune, but slips under power in all gears it must be the forward clutches going out.
No thats not it either?
You need to take it back to the tuner and have him scan it when the problem occurs, this way he can monitor trans slip, etc.
No thats not it either?
You need to take it back to the tuner and have him scan it when the problem occurs, this way he can monitor trans slip, etc.
04-30-2010, 09:38 PM
#7
I have a bit of data back on the trans... Maybe someone could offer some help based on this?
First, the car put down only 350whp on a Dynojet... This is a Torquer 2 cam, full bolt on car. Converter was locked, power goes flat all the way across from about 5k on up... literally like a straight line.
Second, using EFI live, Doc @ EFI Alchemy was unable to detect any slippage in the trans.
Next, using the GM protocol for testing the trans it passes for pressure. Hooked up a pressure gauge to the test port and drove around, it's at 60psi through normal driving, hammer on it and it shoots to 120psi and makes a thunk sound and bounces off the limiter then pressure drops down to 60psi again, then I let off. No clue if it will shift or not if I stay in it, trying to avoid any further drivetrain damage.
I was able to get the car to shift the other day while driving it. I attempted to go through the gears manually starting at a slow roll in 2... I ran it through the powerband, and when putting it in D at around 6k rpm it waited a second till it got to the shift point, then hit 3rd. After pulling for a sec in 3rd I let off. I could get it to do this twice, then it wouldn't do it after that...
Transmission fluid is an orangish color, I haven't pulled the pan to see if there's anything in there yet.
My tranny builder said the pressure should be at 200+ when I go full throttle, he seems to think the trans is done and the converter probably is too.
This is literally pretty much all the info I have...
In regards to tuning questions, I'm open to suggestions, but I doubt this is the problem. DOC is a very well respected tuner in the southeast for LS1s, he races a built 4L60E car himself. I'm very confidant he knows how to tune one.
That being said... any additional ideas?
First, the car put down only 350whp on a Dynojet... This is a Torquer 2 cam, full bolt on car. Converter was locked, power goes flat all the way across from about 5k on up... literally like a straight line.
Second, using EFI live, Doc @ EFI Alchemy was unable to detect any slippage in the trans.
Next, using the GM protocol for testing the trans it passes for pressure. Hooked up a pressure gauge to the test port and drove around, it's at 60psi through normal driving, hammer on it and it shoots to 120psi and makes a thunk sound and bounces off the limiter then pressure drops down to 60psi again, then I let off. No clue if it will shift or not if I stay in it, trying to avoid any further drivetrain damage.
I was able to get the car to shift the other day while driving it. I attempted to go through the gears manually starting at a slow roll in 2... I ran it through the powerband, and when putting it in D at around 6k rpm it waited a second till it got to the shift point, then hit 3rd. After pulling for a sec in 3rd I let off. I could get it to do this twice, then it wouldn't do it after that...
Transmission fluid is an orangish color, I haven't pulled the pan to see if there's anything in there yet.
My tranny builder said the pressure should be at 200+ when I go full throttle, he seems to think the trans is done and the converter probably is too.
This is literally pretty much all the info I have...
In regards to tuning questions, I'm open to suggestions, but I doubt this is the problem. DOC is a very well respected tuner in the southeast for LS1s, he races a built 4L60E car himself. I'm very confidant he knows how to tune one.
That being said... any additional ideas?
Trending Topics
05-01-2010, 08:01 AM
#8
I don't think it's tuning... We were doing on the road tuning with the Moates Roadrunner and EFI Live. Adjustments were able to happen in realtime on the fly. Doc knows how to set up a 4L60E tune, that being said I'm just going to rule it out as a potential tuning issue.
I guess there's not a lot more to talk about in regards to the trans, it's probably dead. I just don't know why I was able to get it to shift a couple times before but not all the time.
