IDK if this will assist anyone, so here goes:
Technical Troubleshooting:
https://gear-report.com/wp-content/...ment_7_4L80E-Transmission_Troubleshooting.pdf
*** SEE PAGE 209 for Temp requirements and sensor resistance values.
Make certain the sensor resistance value is correct before you consider repairs.
If you have any fluid in the connector, the readings will also be incorrect.
If the connector o-ring is leaking in the case or the seals on the wires inside are missing or leaking, fluid shorts out the connector.
Reverse Pressure testing:
https://www.transmissiondigest.com/diagnosing-the-elusive-no-reverse-with-the-4l80-e/
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Spoke with the owner of Compushift, regarding my Comp 2 Stand-a-lone controller.
After installing a 4 ft long high pressure brake line to the pressure port on my 4L80-E, using my compression test gage from OTC, (280 psi instead of buying a separate 400 psi transmission gauge), my rebuild confirms pressures:
70-90 in OD
70-90 in D
90-100 in 2
120 in 1
120 in Rev
@45 in Rev Foot to the floor, NO MORE THAN 2 Seconds.
My engine L31 Roller Stage 4 Sum-8800 cam
Mild Ported to shape of in-ex gaskets 062 heads.
1-5/8"primaries to 2-1/2"c collector's.
2000 RPM stall, Billet converter, (pump and back plate), single Kevlar friction.
4L80-E, roller-ized, Sonnax Loaded, 99' transmission.
*** Required additional Direct Drum machining .041" from the bottom of the drum.***
The OEM Drum did NOT meet the OEM drum spec in the 1999 transmission.
The ASTG Manual did not put the cut specifying this dimension in the assembly instruction, where you would expect it, during the inspection process.
It is much further in the back of the manual.
You MUST verify the Direct Drum specs, before you drive yourself up the wall rebuilding and causing spacing issues.
The Specialty Drum Upgrade from a famous engineering company, charged me $280 for as custom HD drum AND IT DID NOT ARRIVE MACHINED CORRECTLY EITHER.
(Nor would they accept a return to correct it. No Names).
My Re-program, using a completely new Sonnax Valve body, with Rev Over-run valve mod and all the additional Sonnax Pressure/Valve Mods, had the "plug" blow out, causing no reverse.
*** Remember: This ONLY APPLIES TO MY REPROGRAM 4L80-E and may not apply to YOUR Re-Program. Verify plugging as per your reprogram engineer.
The solution was to tap the return port under the valve body, so the plug was no longer required. This meant custom grinding a narrow shaft, tap so it would not break the surrounding case during the NPT plug process. You might not want to use this tap for steel afterwards, because of the strength of the tap afterwards.
The Tap Plug works so the leak or plug blow-out from the Direct Drum is not possible.
There's a bunch of other check ball requirements that can get messed up or confused between re-programmer designs., so I will not go further.
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With all this in mind:
Compushift advised NO ADVANCED settings should be nessesary.
(Your controller may differ).
Base settings should be followed.
The following CS instructions may work for other shift controller's, however confirm with your controller expert, before using this data on your application.
1) Shift Speed: 14-15%
Higher the percentage, the LATER you will shift.
2) Pressure Adjustment: A= 12-14%
Higher the percentage, the faster you will shift.
3) Down Shift: 80-85%
When you Raise the %, Downshift is QUICKER.
85% being max, with a higher HP Stage 4-5 roller camshaft, 5.7L V-8.
Check with your expert before guessing. Every build is different.
No Advanced Settings should bve adjusted.
If you have messed with any base settings, it is strongly advised to reset to factory settings and use the "B" settings as a reset to base refrence.
Any one of these could cause increased heat, when out of specified limits.
Verify your Transmission cooler is not clogged or blocked.
Many coolers get blocked and failure to replace a blocked cooler after rebuild, is your responsibility, not your rebuilder's.
Thousands of transmissions are ruined every month due to clogged cooler.
When in doubt, over-size, add a fan, and throw the old one out.
Now you can start diagnostics and tuning, knowing your harness is not shorted and your cooler is not the issue.
Hope this helps..
