Inconsistent 1-2 shift ('00 w/2.73's)
09-12-2005, 08:33 AM
#1
Inconsistent 1-2 shift ('00 w/2.73's) Hello all,
Tried searching, but nothing came up.
I'm getting used to my '00 Z28 Vert, but I've noticed the quality of my WOT 1-2 shift is pretty incosistent. Only mods are a SLP lid, SLP LM2 exhaust. Z06 knock offs with 275 fusions.
- From a dead launch... most of the time the 1-2 shift is pretty good. It is soft (no bark) but it happens quickly and smoothly pushes into 2nd.
- Often times from a kick down (3-1 or 4-1) by going WOT around 35-38mph the 1-2 shift is all over the place. Thing is, I can't really tell if it is torque management, rev limiter, or just a problem shift. The car pulls up to about 6k, goes for 2nd, hangs for a moment, and then grabs 2nd. Sometimes I'll get a small "pop" or mini-backfire from the exhaust at the same time this occurs. Sometimes it'll be fine. But most of the time the problem seesm to be with a kick down 1-2 shift. Anyone know what this is, and how to fix it?
I'm thinking it's torque management, because the revs don't seem high enough for the limiter to be the issue. I don't want to fully disable torque management if that's what it is, but it drives me crazy. I was thinking maybe a small edit with a predator or similar device could fix this for me.
Also can't do a shift kit for now (still have a powertrain warranty).
Any input is appreciated.
Tried searching, but nothing came up.
I'm getting used to my '00 Z28 Vert, but I've noticed the quality of my WOT 1-2 shift is pretty incosistent. Only mods are a SLP lid, SLP LM2 exhaust. Z06 knock offs with 275 fusions.
- From a dead launch... most of the time the 1-2 shift is pretty good. It is soft (no bark) but it happens quickly and smoothly pushes into 2nd.
- Often times from a kick down (3-1 or 4-1) by going WOT around 35-38mph the 1-2 shift is all over the place. Thing is, I can't really tell if it is torque management, rev limiter, or just a problem shift. The car pulls up to about 6k, goes for 2nd, hangs for a moment, and then grabs 2nd. Sometimes I'll get a small "pop" or mini-backfire from the exhaust at the same time this occurs. Sometimes it'll be fine. But most of the time the problem seesm to be with a kick down 1-2 shift. Anyone know what this is, and how to fix it?
I'm thinking it's torque management, because the revs don't seem high enough for the limiter to be the issue. I don't want to fully disable torque management if that's what it is, but it drives me crazy. I was thinking maybe a small edit with a predator or similar device could fix this for me.
Also can't do a shift kit for now (still have a powertrain warranty).
Any input is appreciated.
09-12-2005, 09:10 AM
#2
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Well 1st of all, our Tach's aren't the most reliable of what your actual RPM is. They are close, but not perfect.
Secondly, it sounds like you are noticing slipping. If you are noticing slipping then it's an internal transmission issue.
How many miles on the the car/tranny. Has it been abused, raced? Has anyone previously modified the transmission shift points?
If you have traction control, you can always turn it off and see if the the problem still happens.
As for rev limiter, you should know what it sounds like when you hit it and ping off the limiter. If you don't know what it sounds/feels like you might want to hit it once just so you know, or have a friend ride with you that knows what hitting the limiter feels/sounds like. The stock limiter is at 6200 and you shoudln't hurt the engine from tapping it occasionally. (No I don't reccomend hitting it normally, but 6200 RPM shouldn't hurt your engine at all.)
Sinc eyou have a powertrain warranty, why dont' you swing it by the shop and have a mechanic go for a ride with you to tell you if it's normal or not.
That would be your easy fix!
Secondly, it sounds like you are noticing slipping. If you are noticing slipping then it's an internal transmission issue.
How many miles on the the car/tranny. Has it been abused, raced? Has anyone previously modified the transmission shift points?
If you have traction control, you can always turn it off and see if the the problem still happens.
As for rev limiter, you should know what it sounds like when you hit it and ping off the limiter. If you don't know what it sounds/feels like you might want to hit it once just so you know, or have a friend ride with you that knows what hitting the limiter feels/sounds like. The stock limiter is at 6200 and you shoudln't hurt the engine from tapping it occasionally. (No I don't reccomend hitting it normally, but 6200 RPM shouldn't hurt your engine at all.)
Sinc eyou have a powertrain warranty, why dont' you swing it by the shop and have a mechanic go for a ride with you to tell you if it's normal or not.
That would be your easy fix!
09-12-2005, 09:46 AM
#3
1.) I didn't realize factory rev limit is only 6,200. So yes, it might be possible. Particularly because of the small exhaust backfire. What's SAFE? 6400? Because if it's the rev limiter I think a small 100-200 bump would cure it. I know what hitting a rev limiter sounds like (gotta love rental cars) but I'm in no way ramming up against it. I might be just barely tapping it, but there is no sustained engagement.
2.) It doesn't feel like slipping. It really feels like the motor being choked - not the motor racing up and the trans not keeping up...
3.) Car has 51k miles. I don't think it was driven hard but it wasn't maintained the best, either. Older guy, 1 owner, traded into same dealer it was bought at type of history. Has not been programmed or tinkered with, far as I can tell.
4.) Turning off ASR doesn't help.
5.) It's a GMPP warranty, which means I have to pay a diagnostic fee that is waived only if the tech finds a problem. This in turn means that unless I have an obviously brokent part, I'm paying $88 to hear "nope that's normal". Anything that is at all inconsistent or subjective will be diagnosed in this fashion, I've already been through that.
6.) I really don't think it did this before the lid and catback. But I also didn't drive the car tons before those mods so I can't say for sure.
2.) It doesn't feel like slipping. It really feels like the motor being choked - not the motor racing up and the trans not keeping up...
3.) Car has 51k miles. I don't think it was driven hard but it wasn't maintained the best, either. Older guy, 1 owner, traded into same dealer it was bought at type of history. Has not been programmed or tinkered with, far as I can tell.
4.) Turning off ASR doesn't help.
5.) It's a GMPP warranty, which means I have to pay a diagnostic fee that is waived only if the tech finds a problem. This in turn means that unless I have an obviously brokent part, I'm paying $88 to hear "nope that's normal". Anything that is at all inconsistent or subjective will be diagnosed in this fashion, I've already been through that.
6.) I really don't think it did this before the lid and catback. But I also didn't drive the car tons before those mods so I can't say for sure.
