Put in a 3:42 in a '03 a4 & at WOT the car was set to shift @ 6190 RPM,way too high,got valve float bad.I've got a Predator & changed a lot of parameters ,ie fan ,trans etc.What would be a good baseline to set shift point rpms,& shift on & off 1-4th gear rpms using the Predator?

Took M. Mercurys advice on a current thread & bumped up the WOT Timming 3* & decreased shift time 7% across the board, & increased shift pressure 7%.This seemed to work very well.The LS1 gets its peak HP @ 5200 RPM I'm thinking thats where to put the above mentioned points & on & off RPMS at?The car has a Blackwing & not much more,in terms of mods.Also the mph shift can me modified ,did anyone out there change that after a 3:42 install?BTW the predator tune is on the car.

 

to set WOT shift points - place your shifter in "1" and then take the car up to redline... note the MPH.

then place your shifter in "2" and drive the car up to redline - note the MPH.

and if you're brave - do the same, but in "3".

then set each WOT MPH shift point 2 mph BELOW what you noted for each gear.

Next, set the RPM WOT shiftpoint for each gear to 6000.

This should get you very close to optimum.

 

As stated appreciate your input.The problem is now the car seems to lose power, & jerk the engine as it shifts anywhere from 5700-6000 rpm,@wot.It seems like valve float ,but it could be the rev limiter,shutting down the injectors?Thinking about going down to about 5400 for on & off shifting rpm,& set the rev limiter to 5600.Anyone else have this problem @ 5700-6000?Actually I once heard that the shift off rpm should be about 50 rpm lower than on?

 

I dunno; the rev limiter on the C5 controls the throttle plate - except maybe in the abuse mode - which I doubt you're causing the abuse mode to kick in.

 

Are you sure you scaled your gears correctly? You may be bouncing the rev-limiter.

Under "Axle Ratio" it will first ask what your stock gears are(ie. 2.73, 3.15 in numerical value)*, then it will ask what the new gears are(ie. 3.42, with a scroll bar to adj. value).

Did you follow the shift points in the addendum?

The addendum reads.
"MPH upshift, downshift and rev limit adjustment for Corvettes with Axle Ratio changes:
Only necessary when putting 3.42 or larger gears:

For 3.42 Gears set the following parameters:
1-2 Upshift MPH 41
2-3 Upshift MPH 80
3-4 Upshift MPH 130
2-1 downshift 36
3-2 downshift 79
4-3 downshift 118
Rev limits @ 6480
Rev Limits ON @ 6479

For 3.73 Gears set the following parameters:
1-2 Upshift MPH 35
2-3 Upshift MPH 65
3-4 Upshift MPH 126
2-1 downshift 34
3-2 downshift 58
4-3 downshift 115
Rev limits @ 6480
Rev Limits ON @ 6479"

From the research I have done, it seems you need to change it under "Gear Ratio" as well as the changes listed above in the addendum.**



*The Predator defaults to 3.42 in this first step. You should change it to your actual stock gear ratio(2.73, 3.15). Even on ver.2.05

**On ver.2.05 it looks as if you do not need to follow the extra steps of the addendum, at least my 3.73's shift fine WOT with just the "Axle Ratio" scaling in the Predator.

Worst case scenario is that you have to flash back to stock and start over.

Good luck,

AZC5

 

AZ, I will try your suggestions.One thing that puzzles me,my Predator ,a v1.03 they said was a current model,does'nt have downshift tables for mph?

 

There is a more current version available. It includes many new options.

AZC5

 

just to clarify; there are 3 model Predators that cover the C5.

1. 1999 thru 2003 exclusive

2. 2003 only

3. 2004 only

the 2003 only, and 2004 only, have the extra adjustment fields. Last I heard, DiabloSport has no intention of offering any software upgrade for the 1999-2003 exclusive model.

Only 2003 year C5 owners have a choice between two of the three model Predators. But the 1999-2003 model does not have the extra adjustments.
The 2003 only model does.

 

Every time I called up Diablosport they told me I had the latest one the 1.03v.The question I now ask is can I fix my problem by using AZ's method,with the predator I have the '99-'03?

 

You must have U7198 which is for 1999-2003, the most current version for that unit is 1.03(my mistake).

If your version does not have MPH downshift, it would be impossible to use the instructions in the addendum. As they call for MPH downshift adjustments.

Try just scaling your gears with the "Axle Ratio" adjustment and do not follow the addendum. If you are still hitting the rev-limiter I would call Diablosport and ask them for a custom tune for your gears, because you keep hitting the rev-limiter.

AZC5