I recently upgraded the 2.56 to the Z06 diff 3.42. Ive since noticed that at WOT roll-on on the on ramp onto the freeway it wont shift and hits 7k, I have to let off and rengage the throttle.

Tuning issue? LS2 is retuned with HP tuners...

 

Did you reset the rear gear and tire size in the tune? I believe you need to have that information in there. I'll go check my tune now...

Yup, I found both items in there. Revolutions of tire per mile and rolling circumference for the tires and the rear gear ratio.

Elmer

 

That will be a question Ill ask my tuner tomorrow. I was getting a traction control active code when I hit 125 (consistently) Im running 275/35/18, 305/30/19 and was told the rear wheels are spinning faster than front but the comp isnt picking it up until 125mph I need 325/30 out back to close the ratio % difference. Could this be related?

 

Yep, it has a bearing on your problem too.

 

OK 1st you DO NOT do a speedo correction for an axle change on a C5/6 because the speedo sensor is on the output side of the axle and not the input side of the trans like on an older F body camaro
2nd--you do however need to make a speedo correction when changing the rear tires--measure the actual tire height and add 1/4 " for growth and input that #--do not use the tire size calculator provide as each brand varies in height

ALSO very important--You MUST make a "shift point correction' in order to have it shift properly---Explains why it won't shift at WOT
why you are getting ABS/TC warnings is because you made a speedo correction for the axle change when it was not needed
By my calculations--your shift point correction is -33% OFF--That is HUGE !!!
With EFILIVEyou can make the shift point correction easily with a one entry change -- Most like HP is the same--Subtract 33% to the entire shift point correction table---It should be fine

 

Sorry, but that's not correct.

Either a gear swap or a tire size change will require the speedometer values to be changed in your tune on an A6-equipped car.

Also, on HP Tuners (not sure about EFI Live) when you make the speedo change it'll give you the option of automatically recalculating your shift points. It doesn't put them exactly where they should be but it will at least get you close.

To the OP, it almost sounds like nothing got changed in the tune so it should be a pretty simple fix.

 

I would think that you are hitting the rev limiter because the traction control is activating ( or thinks it is by miscalculating). When I changed to 3.42s I was getting this also but it was only because the TC was activating. With the TC off the problem went away.

 

Thanks guys. I have to say though this is the only time I will hit the rev limiter. And when I do the DIC does not display tract conrol active. The car seems to change gears otherwise as normal. Its a haphazard occurance WOT.
The speedo sensor for the Z06 is in the diff, on the A6 its in the tranny. In my application the Z sensor is left alone and we utilized the A6 sensor.
My tuner is aware of the tire size and says he may be able to address the 125mph traction control control issue. I havent gotten to speak with him about the rev limiter issue yet.

 

Best is to verify the speedo if there is a confusion on what to do best is to use a GPS at 60 MPH to be sure it's right--it's more accurate at hiway speeds--
Looking at my EFILIVE software--the speedo calculator has the box checked --- for ALL Corvettes regaurless of transmission -(A4--A6--T56)
as a "No change required" OR "transaxle"--also the same for any front wheel drive car-
On the 2007 C6 the actual STOCK gear ratio inputed into both the ECM and TCM calculator says 1.11----??? Which usually is another indication that the axle ratio is NOT important or used
We always use the ECM to adjust the speedo--Not the TCM--On some operating systems --when making a tire change or raising the stock speed limiter you need to set the speedo to read the info from the "ECM" and not "other module" On a Corvette some operating systems don't do it this way--and some OS's do--
Once you can verify the speedometer accuracy--then you would regaurdless of how you got there--subtract the 33% to the entire shift correction table from the STOCK settings
Hitting the rev limiter is a direct result of having the shifts points OFF-
assuming you have a STOCK stall and not a hds/cam type eng with more serious HP
Reason---to command a shift at WOT the TCM must hit 2 parameters
1st the MPH and then the commanded RPM for that gear--
IF the MPH is programmed TOO HIGH it won't hit that 1st parameter and will skip over the RPM commanded point and go all the way to the "safety rev limiter"
Going to a lower gear raio as you did makes those MPH's all to high or too close--Kinda confusing -Its known as the "shift split" On a stockish engine with a stock stall the split can be as low as 700 RPM but the more HP you make and the higher stall you have requires more of a split
On my 98 with apprx 400 RWHP and a 3000 stall my car requires about a 2000 RPM split
You should be able to get the split correct by doing the shift point correction

 

That part isn't true either. While it was the case for the 4L60, 4L65 and 4L80, with the 6L80 the car only shifts at WOT based on MPH.

 

I have the same problem, when I tramp down on it I hit the rev limiter and almost got hit in the rear. Please let me know if you get yours fixed. I'm running 345 / 20 on rear and 285 / 19's on front w/ 342's gears on 07 6 speed auto as well. Thanks

 

Have you guys tried with TC off? Mine does the same thing but only with TC on which is normal.

 

On any T42 trans the software gives you the option to change the "shift qualifiers " from speed only to speed and RPM-----
You are correct that on the T43 they have taken away the option for you to change it--however--Why do they still have a table called "WOT shift RPM " If that table is still there--there must be a reason for it--It is NOT the safety rev limiter--that is a completly different table
So I suspect that they do not want you to mess with it or the software companies haven't cracked those tables yet to let us in--
Often times the software doesn't make sense---The speedo calibrator is another thing that is confusing on the T43--- (i noticed you didn't mention it)---All T43's come programmed with a 1.11 gear ratio stock--so something there is amiss--OR you simply don't have to make a correction--I haven't had the need to change the speedo on an T43 for a gear change yet--as most C6 owners leave the ratio stock--
I HAVE tuned a T43 with a stall converter which would not shift at WOT---(same as above but for a different reason)---I simply lowered the WOT up/down shift MPH's and it began to shift at WOT at the programmed commanded shift RPM of 6400---So whether you beleive it shifts at WOT by speed only-- or by speed & RPM-- all i can say is that lowering the WOT MPH's worked---regaurdless

 

Well a re-tune fixed the problem, thanks guys! It was tire size related.

 

I'm running that combo on my '05 A4...275/35/18F and 325/30/19R and have no problems