Finally got to the track tonight. Fairly humid (fog was rolling in). Wish I had one of those weather stations to see what conditions were for sure. Last I checked it was at 81% humidity (according to the weather channel).

Anyway, I ran her down the track. First run, bouncing off the rev limiter on the 2-3 shift about 6 to 8 times before hitting third gear, I run a 13.20 at 103.

I'm pretty happy at that point... thinking I'll pull the laptop out, adjust shift points and break the 12s by the end of the night.

Well, I had that laptop out after EVERY run tonight and couldn't get that shift to go like it should. The car gets to 5500 rpm, then it acts like it goes in neutral because the tach jumps from 5500 to 6500 and starts bouncing the rev limiter. Usually about 5 to 6 times before it would go into third. No matter what I did in the ecm, this happened on EVERY run.

Nice thing was I had some dead consistent runs. I tihnk I had 3 of them at 13.16x at 103.95x Literally almost identical to the thousandth of a second.

Anyway, by the end of the night, I pulled the K&N (because it was looking pretty grubby) and turned a 13.069 at 104.43 and backed it up with a 13.053 at 104.37 and it's STILL bouncing off the rev limiter.

Any help? I have the 2-3 shift down to 69mph and rpm at 6000. Rev limiter is 6500 and it still hits it when the speedo is showing 80+ and the tach is redlined.

This all started when I went from the 2.73 gears and stock converter to 3.42 gears and SY3500 converter.

Gotta be something I am missing.

 

do you have the obd1 stall becuase anything over a 2800 stall ussually causes trouble. send me your bin file. vincentbergeron@yahoo.com

 

guess I should have mentioned, this is an LS1.

I have ls1 edit. If you have the software I can send you (or anyone else who wants to see it) my .ls1 file

 

sorry i cant help you there...but i tried

 

I ahve been running into a similar problem. I have OBD2 97 trans am with a new Art Carr 4L60E and 3200 stall. on the street the car shifts fine from 1-2 and 2-3 , but at the track when launched hard the car bounces off my 7300 RPM rev limit before the 1-2 shift. It should be shifting at 6900 not bouncing off the limiter. Anyone have an idea? I think it may have to do with launching hard and the car reaching the rev limit be4 the MPH programmed in the PCM, does this make sense?

 

i dont have anyobd2 software. so now that thats out of the way, heres a idea


what ive found with obd1 cars is not really the old (high stall problem) but the coverter slip difference the engine will hit 7300 before it sees the mph. it needs to see both perameters met to make the shift. the mhp may be what the pcm is not seeing, since passes the rpm point first this makes you think the rpm is the problem, but you can try this. lower the rpm shift point NOT THE MPH. the torqe converter slip killed me as far as tuning goes. it took me a while to figure it out. leave your mph alone, use you rpm to make it shift at your mph you want. not the other way around.

a buddy of mine had a 4400 stall, we didnt no it at the time, the guy that built it put the wrong stator in it (was suppose to be a 2800). anyway i had to set the mph to 35 and then set the rpm shift point at 3600 to get it to shift at 6200, just to make up the diference for the slip in the converter. we were able to make the stall work good and didnt even know what size it was. and it made as a good daily driver as well.

i may be way off, i dont have the obd2 stuff, but thats what ive learned the hard way, maybe it would giude you in the right direction, hope it helps

 

i dont believe there is an option to shift by RPM. If there is please tell me where I can edit this.

 

in tunercat it called hot kickdown shift rpm threshold and the pcm has to see that rpm to plus the programmed mph to shift, and when it sees it it will shift.

 

Ahh yes we have this in LT1 edit. The RPM is set to 5300 in this category which is well below the 7300 rpm rev limiter. So what giveS?

 

your runing a 3600 stall theres more thatn 2000 rpm of slip. drop that rpm to about 3500 and see what that does.

now in tunercat there are more than one shifting rpm table, there is hot mode cold mode normal mode. change the cold and hot to about 3500 rpms and see what that does.

if this doesnt work post back and theres one more thing to try.

 

ok thanks I will try that, but I wont be able to test it at the track for a month or two.

My normal kickdown was set to 1054 rpm and hotshift was 5300 , i changed them both to 3500 rpms

 

Sorry to bring this back fromt he dead but, did you ever get a chance to try this? how did it work out?