Performance tuning the 4L60E and 4L80E Transmission VIA PCM
Well you guys know I'm into my first 16197427 PCM but it's a manual... BUT i have a 16188051 PCM in my LT1 with 4L60E that I am starting to play with... :rolleye:
Before I waste a perfectly good, inspected and serviced with synthetic trans I thought I better get some experience before I go to far.
First thing I found out was the 1995 Cadillac LT1 with towing package RPO V4P was a drastic improvement in shifting from factory! Can you believe a Cadillac had better shift points then an Impala SS? Well it does. So I found the V4P bin file and did a lot of comparing and liked the looks of it.
Driving my 1994 RoadmaSSter, that has the towing package, but same shift points as Impala SS was much better, higher shift points more performance oriented and just felt better.
The only other thing I have done to tranny is changed was "Shift Time (sec) Vs. %TPS Vs. Shift, Normal Mode, Low Alt. and High Alt". I cut the shift time in half from approx .60 to .30 and they do seem firmer.
The only reason I touched them was there is another table "Shift Time (sec) Vs. %TPS Vs. Shift, Performance, Low Alt. and High Alt" and these are all set to "0.00 But have no idea what makes the PCM go from "Normal" to "Performance" mode. I'm guessing I will find a TPS parameter somewhere. But both tables are the same TPS readings? So maybe it's switched by a MAP reading?
So what else can be done? Lots of questions on line pressures? Better question is what should NOT be done.
Re: Performance tuning the 4L60E and 4L80E Transmission VIA
I don't usually increase LP substantially on an old or unknown trans. a 10% increase is usually enough to notice. I will decrease desired shift times, adjust the up and downshift speed vs tps, and change the TCC lockup. GM did a nice job of making power with the stock LT1 IMO. The trick is to make the car feel like an SS should feel.
Re: Performance tuning the 4L60E and 4L80E Transmission VIA
There's so many places to change line pressure I didn't even touch them yet. Main/max line pressure is 90 would increasing this be an overall increase?
I did change shift times, a few times and ended up with 0s like in the performance shift time table. Still not sure what paremeter changes to performance mode? Was much better. Biggest and easiest change beleive it or not was the Caddilac V4P Towing package. My car has towing package but tranny paremeters are same for Caprice, 9C1, Impala SS and Roadmaster. Only the caddy got better tranny shift points. Big improvement. Only changed shift times and a few MPH settings from it. Drives nice now, stays in gears longer and actually has a feel, rather then 123 slush 4 slush all day! :laugh:
Was wet yesterday and I floored it at about 10 mph and when it shifted to 2nd the tire just lit up. Need posi!
Your right about LT1 power from factory. I did play with WOT fuel, used a WOT locker program that does something to bin and locks WOT BLM to 128. From there it was easy to add fuel to WOT and watch O2 sensor readings go up and hoover at .890 to .920 when I got 20% more in. I run 93 NO ethonal fuel and added timing 2 degrees at a time from 1400 RPM 45 MAP up. No knock till I got 6 degrees in then only mid range slight knock retard, on a cool humid rainy day. So it would probably be fine all year long but I took out the last 2 degrees.
Data maaster is way cool too! I still have not got TunerPro EE.ADX file to work so I am on trail datamaster. Used the 1/4 mile times from stock tune and got 15.8 second quater mile. Now I am at 14.3 quater mile. Big touque increase on the Datamaster Dyno too. I think I'll have to buy it! :happy:
Re: Performance tuning the 4L60E and 4L80E Transmission VIA
For overall changes in LP I'd use the two main LP vs speed tables. Max pressure of 90, ok, make sure nothing goes above that. Well, maybe 92 psi, just cause ya can't leave it stock. :) Then attempt to dial in gear changes by desired shift time. Watch desired times vs actual on scantool, and use the modifier tables to make spot increases in LP if the trans is having trouble achieving desired shift times. Remember, as you increase main LP, the garage shift LP may need to be reduced to keep trans from slamming into gear. This trick is good for engines with lumpy cam.
Performance shift tables are never used in a stock Impy SS. Only used in the the T/A with the installed "performance / normal" shift button. Similar button can be installed in B-body. Here's some helpful info with a copy of Scott Mueller's original button install writeup for the ImpalaSS forum.
http://www.cadillacforums.com/forums/ca ... 07975.html
Datamaster software is nice. I don't mess with other stuff very often anymore. Not sure if we can buy non-ethanol fuel here. Seems strange to offer E10 only in a climate as humid as ours. All sorts of small engine problems from that combination. And I'm hearing about more rusty tanks and sending units, too. Can't wait to see what happens to the lead and tin coated fuel parts in my '36 Plymouth when I get it on the road.