cpd004

iTrader: (13)

On every 3rd shift at somewhere right around 5500, the car hits the rev limiter twice (so it bogs slightly) and then shifts. This an auto 1998 with a basically stock Ls1, Fuddle and 3.73's. The car came with 2.73's. I'd imagine this a programming problem due to the 3.73's but not sure. Opinions?

vodas00ss

iTrader: (14)

not positive but I think thats a problem with the 98's cpu Had a friend with a 98 z and it would do the same stuff, you would have to let off the pedal then matt it again before it would shift. not sure how to go about fixin that prob

cpd004

iTrader: (13)

Thats what I did on a few of the runs. Any other suggestions?

fortmyerspolice

iTrader: (7)

Maybe it just the tach being slow???

Magnet

iTrader: (36)

a tune wouldn't hurt..

thosewhohatedmecreat

transmission shift kit maybe? tune? try a tune first.

5_02ls1

iTrader: (20)

its in the tune it took me quiet a few trips out to get my shifts set right after the gears and the converter was even worse to retune....this is were those "useless" handheld programmers are really handy....

5_02ls1

iTrader: (20)

oh what did it run????

thosewhohatedmecreat

chevy computers are smart. unhook the positive battery cable, and touch it to ground, this will instantly clear the computer, hook it back up and drive it normally for 10 miles. then give the bitch a try. just an idea, fixed my friends truck.

cpd004

iTrader: (13)

This was my second time at the track and first with this car so I am really new at this...

.7569 Reaction
1.9300 60 ft
5.5250 330 ft
8.5399 1/8 ET
81.23 1/8 MPH
11.1521 1000 FT
13.3572 1/4 ET
102.45 MPH

I'm sure that bog hurts me as the car definitely slows down a bit when it happens.

BrandonDrecksage

iTrader: (1)

if the car was a m6 that would be a the case, but since its an auto, it should matter because the car shifts on its own adn shouldn't hit the limiter in a auto.

HaulinHawk

Tru dat!

Dan Stewart

Probably nothing wrong with your tranny, just typical of putting taller gears in without reprogramming the computer. GM cars computers typically look at vehicle speed and throttle position or engine speed and throttle position. Which one is hard to say without seeing the logic on the computer in particular (not all operate one way or the other). Let's say it's programmed to shift from 1st to 2nd at 40mph at WOT. With taller gears, you'll hit rev limit before you hit the shift mph and the computer will see the logic failed and revert to looking at engine speed to make the shift. Only problem with that is you usually hit the rev limiter before the computer catches on and makes the shift. Simple hand-held programmers will change the shift mph based on the gearing ratio you input into it. PC based programmers vary, as some will automatically calculate shift mph based on gear ratio and others you have to calculate it yourself and make the changes.

In short, typically changing the shift mph on cars with shifting problems after installing taller gears usually cures the bouncing off the rev limiter ailment.

98WsSick

iTrader: (6)

i had the same problem with my car at the track it happened when i tried to shift it myself (auto) same thing into third, rev limiter for a second then went into 3rd. not sure what it is tho. It's not a tranny problem because my tranny is brand new, probably need a tune

cpd004

iTrader: (13)

I was going to get it tuned but don't think it's worth it for a few times at the track in the next two months. I am going with a heads and cam swap over the winter along with long tubes and will get it dyno-tuned afterwards. I was hoping to find someone who does amatuer tuning just for now for a few bucks, but no such luck.

408z28

iTrader: (44)

Mine did that, then I got my hp tuners software and fixed it. I moved the rev limiter up 300 rpm, and the shift point down 200 rpm so the rpm points didnt overlap. It shifted exactly like it should then. So the answer is in a tune.