4l80e tuning
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4l80e tuning I have a 68 firebird with a lq4 and 4l80e in it, ls6 cam, intake, 28 lb. injectors and long tubes, otherwise stock. Also, stock pickup torque convertor, seems to be just fine, idles nice, etc. I have some tuning experience with big stuff and fast systems, and have the motor running great. I want the trans to shift the 1-2 softer under light throttle, as the car will be more of a cruiser, and driven by a woman primarily. It will chirp the tires almost every time, which would be ok if driven hard, but not just driving round town. I made the shifting later than it was originally, and since then it shifts too hard. I really don't want the car in second at 8-10 mph, so I don't want to go back to that. I have the force motor reduced to 1.1 volts (minimum pressure) over the top third of the table, and smoothed the remaining table for a nice transition; this softened everything as expected. Raising these numbers further doesn't help. I was able to raise the base 2-3 and 3-4 to get a sporty, quick shift back, but 1-2 is still too harsh. I lengthened the 1-2 shift time, seems to do nothing, tried increasing the torque reduction, no help, so I expect I need to go inside the tranny and change an accumulator spring or something related. Any ideas or suggestions? Thanks, Rob.
did you read the stickies in the auto trans section look at post #9,https://ls1tech.com/forums/automatic...lush-more.html
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I have read it now, and feel the statement about increasing fluid volume to firm up shifts vs. increasing pressure makes sense. In this train of thought, I think this is what I am asking: what do I change inside the trans to soften second gear apply? Since reducing the pressure with the force motor isn't possible, as all affected values are at their limit, how would I mechanically reduce fluid volume, pressure, accumulator spring pressure, etc.? Thanks for the response!
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I spoke with my local tranny guy, as well as Chris at CK, both gave me some ideas, I will post results when I'm satisfied and what I did. Mods might move this thread to the trans section that I didn't know existed, thanks.
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I did some pressure testing to ensure the trans wasn't in high line or lacking pressure, all checked out within spec, so out with the valve body. As Chris suspected, the check ***** had beaten the stock separator plate up pretty badly, and to not bother him again, I discussed with my local guy and decided to install the hd2 kit I had on hand. Good decision, as the trans shifted too softly afterword, and allowed the stock mapping for the force motor to be re-entered into the tune. A couple more very small base pressure tweaks in the tune and I arrived right where I wanted to be, firm shifts, but I can't get the tires to chirp, ever. As stated, this is for my customer's wife, not a fast or race application; just needs to run great all the time, like a new car, so she will use and drive it.
Contrary to what was stated in the link offered, the computer does NOT have full control over everything in the trans, it fine tunes the transmission's function from the base fluid accumulation and hole sizes, clutch clearances, etc... and sometimes the mechanical side needs some changes. I went with the smallest hole sizing in the plate for shift feel of the 1-2, 2-3, and 3-4, then ramped in a stock pressure map with the force motor, and with the stock, tight convertor, it shifts great. I am sure if it had a 3000 stall convertor, it would be a complete slushbox, but I am very satisfied with my results.
Contrary to what was stated in the link offered, the computer does NOT have full control over everything in the trans, it fine tunes the transmission's function from the base fluid accumulation and hole sizes, clutch clearances, etc... and sometimes the mechanical side needs some changes. I went with the smallest hole sizing in the plate for shift feel of the 1-2, 2-3, and 3-4, then ramped in a stock pressure map with the force motor, and with the stock, tight convertor, it shifts great. I am sure if it had a 3000 stall convertor, it would be a complete slushbox, but I am very satisfied with my results.
