4L60E tuning and downshift problems, trans experts

[viper6383]

I am also posting in another area so I apologize, but I did not see this area. I was going to build a 4L60E to hold a 383 stroke or NOS but sounds like the trans in NOT up for it. I have 190K on the trans so now just wondering what the hell is wrong with my tranny.

I have heard all the stuff about them shifting like crap and more importantly, not downshifting. I have it bad!! I run large tires with 4.56 gears. Everytime I slow up either by braking or rolling, it sticks in a taller gear and I have to pedal it to get a downshift out of it. This has to be hard on it and and am always causious about that.

I have heard about drilling the valve body and all sorts of stuff but those are hard to correct if done wrong. I am wondering if I can solve all my problems with tuning the parameters of the trans?

This is always the 3-2 or 2-1 dowwshift, passing for WOT downshifting seems normal.

Also, this one has got me. When ambient temps are below around 35 degrees, truck will accel from a stop, as I give more throttle, it bogs near to the point of stalling like someone is over engaging a clutch and needs to slip it more. Then, if I whach the throttle a bit, it will seem to unlock form this state and shift normal. These problems are all around the 1/4 throttle area. Normal driving. This problem will persist in other gears until warm. I was guessing the TC was trying to lock up for some reason. Any ideas? Is this a worn out trans or can a quick fix be added? How can I find the source of this issue?

[NEUMANNZZ]

When was the last time the transmission was serviced?

[NEUMANNZZ]

can you post up the shift tables?

[viper6383]

Not real sure what you mean by shift tables. I have some files from Datamaster but yet to find much that I can do with that program. Probably did not look hard enough. As far as service, change of fluid is all it has had in it's life.

Most problems are cured. Timing was retarded from TDC 3-4degrees from wear. Made a huge difference in performance. I guess after thinking about it, all advances are made from that zero reference. Also, when it was cold out, the truck stayed in open loop much longer causing to stumbles. Have not have colder than 35* yet but things have been good so far.

Down shifts still suck but always have. I think a custom chip with some modded downshift parameters would really help all the problems. I should not have to wait for a downshift. Probably similar to the tow/haul mods of later trucks.

[NEUMANNZZ]

the actual tune from the ecm chip will have set parameters to tell it when to shift( in rpm,mph), line pressure, etc. by using software or notepad your able to see the actual tunes parameters in a tabular(tables) format.

[viper6383]

Like I say, I have datamaster and an ALDL cable, just not much time playing with it. I am interested in viewing the raw data in something like notpad. how do you go about doing that?

[NEUMANNZZ]

You would have to have a software program to download your tune or chip data and it will either convert it over to a table or into a notepad(text document) not sure or familar with what datamaster can do for you.

[93V8S10]

Datamaster is a scan program only. You will need to get into PCM tuning to be able to see what the trans settings are, and how to change them. Tuning the trans is the same as tuning the engine. There is lot of info on doing this in the EFI forums. As far as the downshift problem, I'm still too new at tuning to be of any help. Good Luck!