Anyone have a 4L80E program?

Yes, I tried the full flash (fat red arrow) but the computer wouldn't accept it. Said it wouldn't match. So instead I moved files from one to the other last night. It's working well enough at the moment, at least enough to let me get it broken in and get the wideband installed. When the exhaust was put on they installed the bung for it. Right now I've got one of the old O2 sensors with the wires lopped off plugged into the wideband port so as to not damage the sensor by running it unpowered. Eventually the ash tray will become a plug center for the wideband/laptop interface.

I'll still be wanting to try and make that program work if possible though, because when I get things tuned in and working I still want lean cruise.

What's in there now though... man oh man. I took it out for a ride yesterday. Nothing hard since it's not broken in yet, but getting up the interstate onramp at about 35-40 percent throttle it broke the tires loose. This is with 3.42 rear gears with an Eaton posi and 265/70R17 tires, 31.7 inches in diameter. I was very surprised and am really looking forward to getting it tuned in.

Question, how can I correlate a shift to the Force Motor Current fields D3802 and D3803? I tried doing a scan then playing it back with the tune up, but it didn't show anything that I could see. By playing with this field primarily I'm getting the trans to shift the way I want it to for the most part but now I'm getting to where I need to be able to fine tune.

Anyone? Anyone? Bueller?

Hello Telco,

As a disclaimer … I am neither an engineer nor a transmission expert … the following is based on my understanding of the operation of A4 (4L60E / 4L80E) transmissions and past tuning thereof …

The newest technology transmissions (6L80 / 6L90) are fully electronic. Older transmission (TH350 / 700R4 / 4L60) were controlled by fluid pressure, fluid flow, and mechanical devices.

The 4L60E / 4L80E are pressure / flow based designs that interface with electronic components to allow PCM control - essentially a hybrid design.

D3082 (Force Motor Current - positive) and D3803 (Force Motor Current - negative) were used in 1999 and 2000 OS and were homogenized into D3801 (Force Motor Current) in 2001 and newer LS1-B PCM OS. I would recommend upgrading your project to use a 2001 or 2002 OS.

The Pressure Control Solenoid (Force Motor) is the “bridge” or “Rosetta Stone” between physical line pressure (PSI) and Amps (a measureable PCM input - used to represent actual line pressure).

The PCS / PCM relationship was calibrated by the OEM at the time of production - unless the relationship has become inaccurate - it should not be altered.

Shift pressures should be tuned via D0701, D0702, and D0703 values. For these tables to accurately adjust shift pressures, D3801 (PCS / Force Motor) table values must be accurate.

As an example, if you wished to command maximum shift pressure of the 3>4 shift (D0703) at a given Delivered Engine Torque value, you would enter “96” in the appropriate cell of the D0703 table - this would command a transmission shift pressure of approximately 203 to 223 PSI (maximum of 235 PSI).

The above would only occur if the D3801 (PCS / Force Motor) table values were accurate. If you look at D3801 (or D3802, D3803) the vertical column on the left is Torque Signal Pressure (PSI), while the row at the top is TFT. This table attempts to equate the physical transmission line pressure (oil pressure) with Amps - to afford accurate (or reasonably accurate) PCM controlled shift pressures.

Arbitrarily altering this table (D3801) would cause the PCM to receive inaccurate data with respect to the actual physical transmission line pressure. This would cause the D0701 to D0703 tables also be inaccurate / unpredictable - effectively rendering commanded shift pressure to little more than guess work.

GM service manuals describe a diagnostic procedure to confirm D3801 calibration - by measuring transmission line pressure with a gauge, while using a Scan Tool to cause very small changes in the amps output by the PCS.

I’ll try and attach some images below …

Regards,
Taz

Attachment 11414Attachment 11415

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Originally Posted by Telco

Question, how can I correlate a shift to the Force Motor Current fields D3802 and D3803? I tried doing a scan then playing it back with the tune up, but it didn't show anything that I could see. By playing with this field primarily I'm getting the trans to shift the way I want it to for the most part but now I'm getting to where I need to be able to fine tune.

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I don't know that you can correlate the force motor current table to a specific shift (or vice-versa)...

while in gear, the PCM calculates and/or looks up the commanded torque signal pressure [we don't have a table for this];

during a shift, the PCM commands the torque signal pressure from the shift tables [D0701, D0702, D0703];

(torque signal pressure: see the Common Functions hydraulic schematic)

in each case, after determining what the commanded TS pressure should be, the PCM maps TS pressure to force motor current using the FM pressure-current table; the TS pressure will be accurate if this table correctly models the PCS/TFM solenoid (i.e. the table has to match the ability of the solenoid);

you can increase TS pressure across the whole range by decreasing the FM table, or by finely screwing in the hex screw on the back of the PCS solenoid... in both cases the FM table is not correctly modeling the PCS solenoid, so you should check line pressure to make sure it is neither excessive nor low during in-gear and during each shift (see the LP tap on the left side of the case).

Well, the problem I'm running into is no two tables have been the same that I've come across for the force motor pressure, so as far as I know I've never had an accurate force motor table. So if I read what the two of you are saying, I should look into having the dealer download a 4L80E program to my truck then, and have them verify the pressure is correct. This would probably be hard to get them to do since the truck came with a 5.3L/4L60E and now has a 4.8L/4L80E and the trans has modified 1st/2nd gears.

I'd love to upgrade to a 2002 program, but was unable to get my computer to accept one. No idea why. I figure on trying again after I get my various engine difficulties worked out. I'm having a devil of a time getting the oil pan to stop leaking. I swear I'm getting to the point of just buying something outright and driving it as-is. This thing's getting my goat big time.

You could connect a pressure gauge to the line pressure tap and use the scantool DVT controls to check that line pressure ranges correctly... this is probably the best way to do it regardless of whether the FM table is correct.

Post pics of your pan...? Are the bolt holes proud (deformed upwards)...? What gasket are yo using...?

Hello Telco,

Sorry to hear frustration is setting in ... we've all been there. Your comments above about resorting to going to a GM dealer for support are not what I was trying to express .. in very plain language - leave the the PCS / Force Motor values stock and tune your shift "feel" via shift pressure, shift time, and torque reduction. You can do this on your own - it will just take a little time.

I generally tune the "normal" shift mode to be compatible with daily driving, and the performance mode (Tow / Haul) for either towing duty or drag strip duty - depending on the intended secondary use.

Regarding your PCM not "accepting" a 2002 OS - if your are using an LS1-B PCM with service number 09354896 or 12200411 - either of these should be compatible with 2002 OS 12212156.


Regards,
Taz

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Originally Posted by Taz

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tune your shift "feel" via shift pressure, shift time, and torque reduction
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Telco, these^ are the keys, especially TR.

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Originally Posted by joecar

Post pics of your pan...? Are the bolt holes proud (deformed upwards)...? What gasket are yo using...?

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Sorry, I don't have any pictures, but the pan was a new GM piece that had the gasket riveted on. The bolt holes are not deformed, the pan surface and engine surface are flat. The gasket called for is an aluminum piece with a rubber ring around it, and the book says to use sealer in the corners.
It would lose a quart over 100 miles of driving. On the plus side, no need to worry about rust under the truck. :doh2: I pulled the pan off from under the truck and used a new gasket, this time with Great Stuff on either side of the gasket. I also let it sit overnight before putting the sealer and new gasket on, and wiped all surfaces down with denatured alcohol until they were oil-free. It doesn't leak as bad now, but it still leaks, hence the engine pulling I'm about to begin. I never have been able to get an oil pan to seal correctly from underneath, but decided to try it again since the design of the GMT800 truck makes it look easier.

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Originally Posted by Taz

... leave the the PCS / Force Motor values stock and tune your shift "feel" via shift pressure, shift time, and torque reduction.

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This is what I was expressing as having a problem with. I've looked at a dozen supposedly stock tunes, every single one of them has had widely different numbers for the force motor. I don't know what the stock values are supposed to be to begin with. Since the numbers did vary so much from one program to the next, I decided to adjust using the force motor parameters, and have had the most luck in smoothing shifts out.

I'll try again on loading the 2002 program, it would be preferrable to start with that one from scratch rather than do the 2000 program then start over again with a 2002.