99 trans issue
Thread Starter
Instructor
Joined: Dec 2016
Posts: 125
Likes: 9
From: Indiana
99 trans issue
howdy, got a trans question.. my 99 auto vette with approx. 85 k on it has been experiencing an issue under WOT where it has been hitting the rev limiter between 2 and 3rd gear. it started off as a brief hint of the rev limiter however it has been progressively worse. tonight it didn't want to upshift until I pulled my foot out of it. Im thinking its and internal issue.. no codes and shifts fine thru all gears at partial throttle.. any ideas? if I need to replace the trans, I'd like to upgrade to a built trans, who do we recommend here on this site? thanks in advance!
Safety Car
Joined: Mar 2016
Posts: 3,534
Likes: 432
From: Atlantic Beach FL.
Possible shift solenoid sticking. They can be replaced from the pan. The 1-2 and 3-4 solenoids are the same part. It could be an easy fix.
I'm not really a transmission guy though.
If I were getting a built trans I would get one from RPM. They have a good reputation here.http://www.rpmtransmissions.com/page8.html
I'm not really a transmission guy though.
If I were getting a built trans I would get one from RPM. They have a good reputation here.http://www.rpmtransmissions.com/page8.html
Last edited by Rob 02; Oct 19, 2017 at 03:46 AM.
Drifting
Joined: Nov 2014
Posts: 1,964
Likes: 105
From: Switzerland
im seeing exactly that from time to time, i have a blower though, so i think the trans is slowly giving up the ghost. its the 2-3 shift, the other ones i dont know, because they never happen under full power. i have been wanting to raise the line pressure by turning a screw inside the trans (they say 1/4 turn), but you really would need to hook up a gauge when driving to see what you are doing and open the trans several times. they say you can go 10-15% higher, from 900 psi stock i believe.
not sure if this would really help. does anybody know?
edit: do you have any mods on the engine? if its accelerating faster than stock, its possible you vehicle speed threshhold needs lowering in the tune.
not sure if this would really help. does anybody know?
edit: do you have any mods on the engine? if its accelerating faster than stock, its possible you vehicle speed threshhold needs lowering in the tune.
Last edited by romandian; Nov 6, 2017 at 03:44 AM.
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IF you need to replace/rebuild the tranny, RPM would be a great choice.
Safety Car
Joined: Mar 2016
Posts: 3,534
Likes: 432
From: Atlantic Beach FL.
im seeing exactly that from time to time, i have a blower though, so i think the trans is slowly giving up the ghost. its the 2-3 shift, the other ones i dont know, because they never happen under full power. i have been wanting to raise the line pressure by turning a screw inside the trans (they say 1/4 turn), but you really would need to hook up a gauge when driving to see what you are doing and open the trans several times. they say you can go 10-15% higher, from 900 psi stock i believe.
not sure if this would really help. does anybody know?
edit: do you have any mods on the engine? if its accelerating faster than stock, its possible you vehicle speed threshhold needs lowering in the tune.
not sure if this would really help. does anybody know?
edit: do you have any mods on the engine? if its accelerating faster than stock, its possible you vehicle speed threshhold needs lowering in the tune.
AFAIK line pressure is computer controlled and increased with a tune.
The stock trans isn't really built to withstand big HP and torque.
If you search the web for 4L60E 2-3 shifts you will get a ton of results.
I agree with Vetteman Jack on the RPM trans. They can build a 4l65e for what ever mods you have and have a excellent reputation and customer service. They won't sell you anything you don't need. You cant beat them.
Drifting
Joined: Nov 2014
Posts: 1,964
Likes: 105
From: Switzerland
yes, pressure is computer controlled at part throttle and up to the max pressure. that is set with the adjusting screw. so you can have brutal shifts at pt with the car going sideways, but no improvement at wot.
i also heard about overfilling the trans a bit. thats also on my list, but you need to tilt the car.
i also heard about overfilling the trans a bit. thats also on my list, but you need to tilt the car.
Thread Starter
Instructor
Joined: Dec 2016
Posts: 125
Likes: 9
From: Indiana
im seeing exactly that from time to time, i have a blower though, so i think the trans is slowly giving up the ghost. its the 2-3 shift, the other ones i dont know, because they never happen under full power. i have been wanting to raise the line pressure by turning a screw inside the trans (they say 1/4 turn), but you really would need to hook up a gauge when driving to see what you are doing and open the trans several times. they say you can go 10-15% higher, from 900 psi stock i believe.
not sure if this would really help. does anybody know?
edit: do you have any mods on the engine? if its accelerating faster than stock, its possible you vehicle speed threshhold needs lowering in the tune.
not sure if this would really help. does anybody know?
edit: do you have any mods on the engine? if its accelerating faster than stock, its possible you vehicle speed threshhold needs lowering in the tune.
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Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 326
From: CA.
St. Jude Donor '13-'14-'15
This is a common issue with modded engines----It is also common when changing gear rear gear ratios or changing the rear tire height from stock
However it is easily tuned out with proper tuning---It is rather complicated to explain--but the simple fix is to LOWER both the WOT upshift and WOT downshift speeds in your tune--( in the gear shifts that hit the safety rev limiter)
So if the 2-3 shift is not shifting and hitting the safety limiter--You must LOWER the WOT upshift and downshift speeds---If the stock up/down WOT speeds are like 75 MPH lower them to like 70--- On a modded engine there must be at least a 1000 RPM split between the WOT shift RPM and what the RPM's are at the WOT shift speed---
However it is easily tuned out with proper tuning---It is rather complicated to explain--but the simple fix is to LOWER both the WOT upshift and WOT downshift speeds in your tune--( in the gear shifts that hit the safety rev limiter)
So if the 2-3 shift is not shifting and hitting the safety limiter--You must LOWER the WOT upshift and downshift speeds---If the stock up/down WOT speeds are like 75 MPH lower them to like 70--- On a modded engine there must be at least a 1000 RPM split between the WOT shift RPM and what the RPM's are at the WOT shift speed---
Thread Starter
Instructor
Joined: Dec 2016
Posts: 125
Likes: 9
From: Indiana
This is a common issue with modded engines----It is also common when changing gear rear gear ratios or changing the rear tire height from stock
However it is easily tuned out with proper tuning---It is rather complicated to explain--but the simple fix is to LOWER both the WOT upshift and WOT downshift speeds in your tune--( in the gear shifts that hit the safety rev limiter)
So if the 2-3 shift is not shifting and hitting the safety limiter--You must LOWER the WOT upshift and downshift speeds---If the stock up/down WOT speeds are like 75 MPH lower them to like 70--- On a modded engine there must be at least a 1000 RPM split between the WOT shift RPM and what the RPM's are at the WOT shift speed---
However it is easily tuned out with proper tuning---It is rather complicated to explain--but the simple fix is to LOWER both the WOT upshift and WOT downshift speeds in your tune--( in the gear shifts that hit the safety rev limiter)
So if the 2-3 shift is not shifting and hitting the safety limiter--You must LOWER the WOT upshift and downshift speeds---If the stock up/down WOT speeds are like 75 MPH lower them to like 70--- On a modded engine there must be at least a 1000 RPM split between the WOT shift RPM and what the RPM's are at the WOT shift speed---
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 326
From: CA.
St. Jude Donor '13-'14-'15
The only way to properly fix this is by using either EFILIVE or HP Tuners software----No handheld tuner will address the proper tables to fix this issue