ejbta

i have a 2000 trans am with boltons and reciently installed a yank ss4000 tc i sent my ecu to frost to have it tuned to shift at 6100 rpms. it shifts at 5500 but the shift points are set right and my tach reads right because my rev limit is set at 6150. i can manually shift and hit the rev limiter at 6150. so whats the deal?

edcmat-l1

iTrader: (10)

The deal is you can't get them perfect via mail order. He can't, I can't, no body can.

Rhino79

iTrader: (7)

Mailorder is just so difficult to get in 1 try. The shifts have to meet mph in the wot vs mph table as well as rpm at wot to command a shift. If the mph is too low, it will cause a short shift, and if the mph is to high it will cause an over rev before the shift. Even on my stock converter stock trans when tuning, I set the rpm to the desired then alter the mph tables accordingly until the shifts are within 50 rpm or so of commanded. Not a fault of frost at all, if you were having a street or dyno tune done, it wouldn't be done in 1 pass. You would have to reflash and repeat until correct. That is the sacrifice with a mail order vs a live tune.

Slowhawk

iTrader: (12)

Thats the answer.

Good part is it is shifting before the limiter. Now the tune can be moved up slowly to get the right rpm. Problem is there might be some mailing back/forth.

redtan

iTrader: (5)

Clearly it's not tuned right. Just setting the shiftpoint at 6100 by itself usually won't be enough. You have to adjust other parameters, such as shift speed. If it's not meeting that requirement, it won't shift as desired.

jimmyblue

iTrader: (11)

If you are short shifting (early) then look at the TPS voltage
at WOT. You may have a fault condition that just doesn't
persist long enough to set a code. If you see over 4.7V
you need to check why (over-enthusiastic bump-stop
hogging is one way).

Of course a mail order tuner has to go without the ability to
check for such stuff. They have to assume everything on the
mechanical side is proper.

JonCR96Z

iTrader: (33)

I can't believe that he really set your shift points to 6100 with a 6150 limiter. Especially considering that the stock limiter is at 6200.

4L60e always shift later than commanded, but theres no way to know exactly how much later without logging. Some only need to be commanded 50-100 rpms early and I've seen some that need 1000rpms. And even still just because the limiter is set to 6150 (if it is) it still may see a few rpms higher (mine is set at 6800 but I've seen 6950 in my logs).

I would bet that either your limiter is higher than you think and it's shifting close to 6100 or he just tried commanding it early to make sure if shifts in time and your trans just gets it done quicker than most.

second_2_none

iTrader: (6)

Thats the other key! If you want to be spot on you have to have it logged to see whats really happening and going on. Hell for some reason my 60E shifts earlier then commanded. Just stuff you'll never know until you log it.

JonCR96Z

iTrader: (33)

What did yours shift at? And do you now what is commanded?

Your 1-2 shift is commanded higher than you rev limiter. Usually the 2-3 is the slow shift on a 4l60.



Not only that but on the track they sometimes shift higher as well. When I changed my gears my car would shift around 6000 on the street, but at the track it would be all in my 6600 limiter (wouldn't even shift at all on the 2-3). I tried lowering it a little at a time and it took me 3 tries to get it out of the limiter.

second_2_none

iTrader: (6)

I think you hit the nail on the head. It was the 1-2 shift that was the issue, it was shifting at like 6300 while the other shifts were at 6800. He had to set the command at like 7200 or 7300 for it to shift at 6800rpm. Sounds like you may have done this a time or two haha

JonCR96Z

iTrader: (33)

Your 1-2 is set for 7100 and your 2-3 is set for 6500.

second_2_none

iTrader: (6)

Gotcha.

01ssreda4

iTrader: (96)

Though trans tuning may seem cut and dry to the novice, it can be kinda tricky with a bigger converter. You really need to do live logging and adjusting to get it perfect. My 1-2 shift take about 75rpm after being commanded to be completed but my 2-3 while in D takes 175-200 rpms to take place, and thats with a built trans and a Yank 4k. And I'd be willing to bet every car is different.