Installed rebuilt trans, now will only shift when you left off gas?
Thread Starter
Registered User
Joined: Dec 2001
Posts: 355
From: clinton twp. MI, USA
Installed rebuilt trans, now will only shift when you left off gas?
I just installed a rebuilt trans into my car. Now it will not shift only untill I let off the gas? Light or WOT, it will not shift. When I let off the gas it shifts? Whats going on here? No codes. 1995 4l60e.
Help!
Help!
Registered User
Joined: Nov 2003
Posts: 1,756
From: West Linn, OR
Re: Installed rebuilt trans, now will only shift when you left off gas?
I'd say contact the builder and let them know what is going on... It could ba a number of things, from the bolts put into the wrong holes in the valve body to flow issues...
Registered User
Joined: Dec 2002
Posts: 1,810
From: Indiana
for a problem like this, you can pretty much cross off all the related systems, like "plugs and wires" (
) or more realistically any engine inputs that determine transmission functions. Since it is shifting, that tells me you do have pressure. pressure test it if possible. if you think pressure is enough and nothing is slipping, you're going to want to look for throttle valve functions. These tranny's dont use governors, but look for something in the same principles. Possibly your throttle valve or modulator is not right. I don't know too much about the 4l60e, but this is usually something a throttle valve or incorrect "feed pressure" (as some manufacturers call it) can cause. Basically, the pcm calculates the excact pressure and timing it needs to shift the transmission based off of your TPS angle, engine load, and vehicle speed as you already may know. If something was wrong there, you'd get a code. since you are not getting a code, that tells me your inputs are fine.
) or more realistically any engine inputs that determine transmission functions. Since it is shifting, that tells me you do have pressure. pressure test it if possible. if you think pressure is enough and nothing is slipping, you're going to want to look for throttle valve functions. These tranny's dont use governors, but look for something in the same principles. Possibly your throttle valve or modulator is not right. I don't know too much about the 4l60e, but this is usually something a throttle valve or incorrect "feed pressure" (as some manufacturers call it) can cause. Basically, the pcm calculates the excact pressure and timing it needs to shift the transmission based off of your TPS angle, engine load, and vehicle speed as you already may know. If something was wrong there, you'd get a code. since you are not getting a code, that tells me your inputs are fine.
Supporting Vendor
Joined: Oct 2006
Posts: 1,014
From: BLOOMSBURG PA
A few questions ,
1- how do the shifts feel?
2- is the converter stock ?
And a STATeMENT the timing of a 4l60e shift is strictly PCM controlled based on variables such as TPS VSS RPM
Please let me know these things and perhaps what your original trans acted Like and ill be glad to try and help
1- how do the shifts feel?
2- is the converter stock ?
And a STATeMENT the timing of a 4l60e shift is strictly PCM controlled based on variables such as TPS VSS RPM
Please let me know these things and perhaps what your original trans acted Like and ill be glad to try and help
Registered User
Joined: Mar 2002
Posts: 3,634
From: Newark, Delaware
Is it the original transmission out of the car?
There are a number of things that contribute to 4L60E shift timing. They don't use a throttle valve, governor, or modulator (unless somebody built it wrong).
They use VSS, engine RPM, and TPS voltage to schedule shifts. There are also a few things internally that may cause this.
I'd put a scanner on the car, and run a data test to see when the computer is commanding the shift to occur. This would help seperate an internal/external transmission problem...but...if you didn't have any timing issues before, it's most likely something in the transmission.
Frank
CPT
There are a number of things that contribute to 4L60E shift timing. They don't use a throttle valve, governor, or modulator (unless somebody built it wrong).
They use VSS, engine RPM, and TPS voltage to schedule shifts. There are also a few things internally that may cause this.
I'd put a scanner on the car, and run a data test to see when the computer is commanding the shift to occur. This would help seperate an internal/external transmission problem...but...if you didn't have any timing issues before, it's most likely something in the transmission.
Frank
CPT
Thread Starter
Registered User
Joined: Dec 2001
Posts: 355
From: clinton twp. MI, USA
Bringing up an old thread here..... Problem was that servo on the pass side of the trans. Builder cut an o ring there. Trans didnt last long after that..... I had it rebuilt 4 times last year and it is still down now. I guess thats what you get when you trade a snowmobile thats worth about $500 to get a hi-po trans built. The guy even worked at American transmisson too.
Registered User
Joined: May 2006
Posts: 280
From: Kansas City
check this out i think it will help http://www.z28.com/forum/showthread.php?t=9437
Registered User
Joined: Feb 2006
Posts: 132
Bringing up an old thread here..... Problem was that servo on the pass side of the trans. Builder cut an o ring there. Trans didnt last long after that..... I had it rebuilt 4 times last year and it is still down now. I guess thats what you get when you trade a snowmobile thats worth about $500 to get a hi-po trans built. The guy even worked at American transmisson too.
Good luck.
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