mtb989s

iTrader: (1)

First off I have searched and found many threads on this topic and all of them just say the transmission is bad, and since we know this transmission is not they didn't really help a lot.

So i'll try to keep this short and sweet.

Basically I had a 4l60E built about 2 months ago, it was rated at about 875 HP. We installed it and had been tuning on it when we ran into a problem. During WOT the transmission will not shift from 2-3, it will go until either it hits the rev limiter or I let out of the throttle about 5%-15% and it will shift crisp. Today I had it hooked up on a shaeffer shifter, we were able to tell that it was not the transmission that had the problem but something with tuning or other electrical. When the transmission was told to shift with the shaeffer shifter it would do it every time it was told. We tested it from 5500 rpm up to ~6400 rpm.

We have adjusted the tables with my HP tuner and nothing seems to work.
Currently the shift rpm is set at 6250 for a WOT 2-3 shift. We have also played with the shift properties MPH. I need some more ideas on what the problem could be? Any suggestions would help.

A little about the
-Full suspension
-Moser 9"
-3800 TCI stall
-Heads and Cam
-150 NX wet kit that I can't use until this problem gets fixed

I can have a log file tomorrow and I also have the flash file so any of you would like to see the tuning adjustments that have been made. Just let me know.
Thanks

kpowr82

iTrader: (9)

maybe a bad solenoid. there is an A and a B solenoid that control shifts when the shifter is in D. have you tried manually shifting from 1 to 2 to D

mtb989s

iTrader: (1)

I can manually shift it and it still will hit the limiter?? Thanks for the input.

kpowr82

iTrader: (9)

another thing you might want to double check is the 3-2 downshift mph. If the 3-2 and 2-3 shift mph don't jive, that could give you trouble.

I'm just throwing some simple things out there. Not trying to insult your intelligence, just making sure you have all your bases covered.

Sounds like a tuning issue for sure though.

kpowr82

iTrader: (9)

btw, have you tried setting ALL of your transmission settings in HPT back to stock. That was one I troubleshot my trans problems. Still turned out to be a burnt 2-4 band though

ChevPower

iTrader: (8)

I had a similar problem before it turned out to be the tunner had the out put speed sensor set up wrong

shortdog

iTrader: (1)

Mtb989, check this out and make sure to read the whole thread: https://ls1tech.com/forums/automatic-transmission/490146-weird-tranny-problem.html

Hope this helps a little..

mtb989s

iTrader: (1)

Thanks for all the help guys. kpowr82 anything you say wouldn't insult me. I'm all ears to any solution right now. The first thing we tried was to set all the tables back to stock and go from there, but it didn't help. Next I placed the tune back on the car and set my shift mph to 60, I thought maybe I had it a little too high and this would be a safe mph to check it. But it still tacked the limiter.

Thanks

mtb989s

iTrader: (1)

shortdog,

I read that thread before you had made the last couple of posts. I have actually shut off the 757 and 751 code and it didn't help. I haven't checked the 502 code yet. Is there a way to tell the vss is bad without replacing them?

I'll test the 502 code today and give you my results later today.

Thanks for that link!

kpowr82

iTrader: (9)

so how'd it go? did the 502 code work?

mtb989s

iTrader: (1)

I'm getting ready to go out and work on it a little more. I'll post the results late tonight.

LS1-Master

I use to have the same problem and i got the jet performance billet servo and it is working very well and the 46-mod Vacuum pressure modulator from Por-Build and the part number for the servo is 750212 and 750213.


MO.

mtb989s

iTrader: (1)

thanks for those part numbers, I'll definately check into these and see what the prices are. Right now it has the fairbanks billet servos in it, but I don't think it has the vacuum modulator??

As for the other stuff I tried none of it worked today. I checked the fluid and added a little more just to be safe. I also took care of the 502 code, even though it didn't show up as a current DTC. I also adjusted the line pressure up a little and set my shift point at 6100 and the rev limiter to 6700. It still tagged the rev limiter every time. When I logged it I found it kind of strange. I exported the data to excel and when it actually hit the rev limiter (6699) it wasn't in second gear but it was actually in third gear? Is this just the tuner reading it wrong or does it actually shift and then automatically hit the limiter??

kpowr82

iTrader: (9)

If I'm not mistaken, you are logging the COMMANDED gear. The PCM is likely commanding 3rd gear at exactly that point but still isn't shifting.

mtb989s

iTrader: (1)

I checked and it was logged as "trans current gear." I'm new at the transmission diagnostics with HP, so thanks for the clarification.

stripes1987

iTrader: (6)

i am having the same problem, the car wont shift from 2-3 without hitting the limiter only at the track for some wierd reason my buddy john is also my tuner so he even reset the shift points to 6500rpm and the limiter at 7300 for the last pass of the night and it never hit the limiter but it fell completely on its face and wouldnt shift. im still trying to figure out what it could be!!!

mtb989s

iTrader: (1)

If you find out let me know, I have tried everything except buying a new tranny.

jimmyblue

iTrader: (11)

One thing to check, in the force motor table look for
a crazy high current in the rightmost column. This
means, if you ever get over 96% commanded line
pressure, blow it all off to nothing. If you mess around
the shift pressures and raise the cap value you could
slide over into this and end up with minimum holding
pressure for the frictions. Set that rightmost column
to the same as its neighbor, or zero even.

WeeWolf

iTrader: (16)

mine's doing the same thing, but mine is vacuum modulated so i don't think the force motor would have anything to do with it. i have another valvebody i'm going to try, but i have my fingers crossed. oh well, here comes the a3 if i can't figure it out soon.

PBA

The 4L60E has a complicated oil circuit, when it is trying to make a 2-3 WOT shift, and sometimes it takes some work to get the 2-3 shift down. First you say it is rated at 875HP, I find this very hard to believe, but, do you know what is in this unit, or what has been done that is supposed to hold this kind of HP? Second, what HP are you putting out at the flywheel, without NOS? You say that you had it hooked up on a shaeffer shifter?, did you do a 2-3 WOT shift with it?, and what happened?