View Full Version : Hitting Rev limiter 1-2 my solution


cookietime
05-02-2012, 02:24 PM
My pcm has been back and forth from tuner numerous times to try and solve my 1-2 shift rev limiter. The last advice I got was to buy software, or get someone locally to tune my pcm.
So I purchased a tunercat with data logger, 2 weeks later Im figuring things out.
I have a baby cam in my 94 camaro from 5000rmp - 5500rpm range with about 70,000 miles. (along with bigger tires, 3.73 rear)
But I kept hitting rev limiter set at 6495 , well outside my rpm range.
So tuner lower my shift points to around 5100 rmp, no change.
I learned from this site and various other sites , shift tables require RPM change AND MPH up/down shift points settings.
I could see mine mph shift points , on tunercat, were set at wot 1-2 shift,47mph,2-3 shift,87mph, and 3-4 shift at 145mph.(Watch these values)
But didnt have any references, until now.
http://www.f-body.org/gears/ is a plug-in caculator to help see RPM vs MPH.and (SHIFT POINTS)
So I plugged in my year and type car, tire size, and rear end ratio.
shift 1st 2nd3rd 4th
5000 36 67 109 155
5100 36 69 111 159
5200 37 70 113 162
5300 38 71 115 165
5400 38 73 118 168
5500 39 74 120 171
5600 40 75 122 174
5700 41 77 124 177
5800 41 78 126 180
5900 42 79 128 183
6000 43 81 131 187
6100 43 82 133 190
6200 44 83 135 193
6300 45 85 137 196
6400 46<86 139 199 <<<
Remember my redline was 6497 , and my 1-2 shift was 47 mph, that means i was winding it past 6495 rpm.
So I lowered it to the 6200rpm values, across the board , and test drove ,Bang no revlimiter, nice solid shift.
Since my powerband is in the lower RPM range, Im going to lower to the 6000 rpm range, and do some testing and tuning.

There is tons of tuning information here and on the web.
If this helps 1 person, Ive done my good deed for the day.
And I wont trash any of our tuners, Im sure they forgot more than Ill ever know.
But this worked,(is working) for me.

a little more info can be found at : http://www.lt1pcmtuning.com/tips/
http://ls1tech.com/forums/automatic-transmission/1416477-how-4l60-65e-trans-tuning-shifting-tcc-tm-w-pics.html

96capricemgr
05-02-2012, 02:32 PM
I like tunercat, his service is great, pricing amazing, but the product can be a handful to learn and difficult to navigate.

Took me quite a while to find a setting in a "kickDOWN" table that was stopping me from turning my setup to higher rpm. Kickdown is not somewhere I thought to look till I got desperate and started looking at every tranny related table.

Keep in mind under normal circumstances there is rpm rise from shift command to completion, you need several hundred rpm between command and limiter AND in cold weather when the engine is making more power that rpm rise will grow so if the touching the limiter problem returns in good weather now you have a clue to work with. Also the 4L60E does NOT like to be overcooled which can again show up in cool weather. I can see another 150-200rpm of rise during the shift cold weather/tranny vs hot weather warm tranny. My tranny is 8 years old and built for a cam only setup so with a fresher tranny and less power you might not see that much variation but I do.

Bigtoyz
05-03-2012, 04:02 AM
Thanks for the info I was gonna start to optimize my stift points so you saved me a ton of trying to figure out where I was at to what I need.

+1 :cool:

pboxfun
05-03-2012, 10:06 AM
Great information! I've been trying to figure out how to tweak my shift points as well. Ive got a question for you that's been stumping me. How do I take the information I get from http://www.f-body.org/gears/ and put that into normal mode up/down shift points on tunercat? Since tunercat uses tps instead of rpm. Also how do you know what mph the car should down shift at?

moehorsepower
05-03-2012, 11:15 AM
There are many ways to adjust shift points, the method you choose is one of many. Will this method work all the time for all? No but its a good reference for those that are having problems, I suggest that before tuning parameters in the PCM, do all manual checks, fluid level ect

cookietime
05-03-2012, 04:24 PM
my 6000 rpm values from http://www.f-body.org/gears/, are now my wot shift points(=100% tps). Everything else adjusted accordingly. Much more info here @
http://ls1tech.com/forums/automatic-transmission/1416477-how-4l60-65e-trans-tuning-shifting-tcc-tm-w-pics.html
This is obd11 , but same principle. attched is my old and new shift tables.

pboxfun
05-04-2012, 09:37 AM
So when I change the 100% tps to whatever rpm values from http://www.f-body.org/gears/ that I'm trying to get, the rest of the chart will change automatically? I'm about to read the link you posted now. Thanks again for your help.

trilkb
05-04-2012, 06:40 PM
Do you leave the downshift tables the same when you change the other? according to mine its set up to shift at 49mph, with my gears and tires is 6300 rpm. So im probably spinning to 6450-6500 befor it actually shifts. stock bottom end lol. Im going to change it to shift at 6100 I think, Im probably getting valve float up there anyways.

cookietime
05-07-2012, 06:47 AM
this is taken from the ls1 tech 4l60e trans shift adjustment.

Also, we need to adjust the downshift MPH by the same percentage that we adjusted the upshift MPH. Although, the uphift MPH has to remain higher than the downshift MPH. You'll see how I modified those variables as well. Notice I added about 2-3MPH to each upshift point except for the 3>2 downshift. This is where further custom tweaking comes in. For me, I dont want my trans downshifting into 2nd gear at 79 MPH if I go WOT or manually pull down because I feel it is too close to the shift out point and dont want the engine screaming for a second before it shifts. It generally feels like its holding back and slower when the downshift is really close to where the upshift is. Id rather just stay in the gear Im in (this case 3rd) and continue to climb. Adjust to your tastes

You need to remember to change the values in all three tables normal, performance and cruising, to take effect.
If you print out my two tables, side by side it should make more sense, your wot or 100% TPS will be your highest rpm value and lesser as until around 50% tps or so .
Again your downshift values need to be lesser than your upshift vales.
Again compare my two side by side and see if you can catch on to the pattern.
mine still has some tweaking to be done , but its a starting point for my smaller cammed goals.