Holding 3rd gear on dyno questions....

[Billiumss]

I have heard that some people adjust the shift table to hold 3rd on the dyno so it doesn't downshift into 2nd when you make a WOT pull.

I haven't done it yet on the few auto cars that I have done, but what settings/tables do you adjust? I was thinking setting the 2-3 shift to 35mph and the 3-2 shift to 30 mph across the board but do I have to do it to all 3 tables or just one?

Post a few pics of your tables if you could or just email a file that shows it: [email protected]

Thanks in advance

Bill

[redhardsupra]

set all your partial throttle tables to match your WOT tables, ie:

1->2 15....15
2->3 25.....25
3->4 120....120
this way it will never be in any other gear than 3rd between 25 and 120mph

[12secSS]

Just use the VCM controls in the scanner to lock the transmission into 3rd gear, then you can lock the TCC. Once the dyno run is over unlock the TCC and deselect the 3rd gear on the VCM Control of the scanner. No need to go through all that trouble.

set all your partial throttle tables to match your WOT tables, ie:

1->2 15....15
2->3 25.....25
3->4 120....120
this way it will never be in any other gear than 3rd between 25 and 120mph

You would also have to modify your downshift tables:
Shift 0TPS%...100TPS%
2->1 0....................0
3->2 10..................10
4->3 20..................20

[ChrisXotic]

I have found it easier to let the cust. get up to 15mph or so and "roll" the throttle to the floor, letting the car/truck shift on it's own to the top of 3rd.
All Gear pulls can also help you make shift points.

Making a single gear pull is tough, although it can be done. You can't get to "snappy" w/ the throttle, slowly get the car/truck up to 55-60?, then roll the throttle to the floor. If you're still downshifting then try again 5mph faster, before going to WOT.
IF you do downshift and complete the pull, or make an "all gears" pull, always view your runs vs. "speed" and ignore the spikes. You must click on the graph to get the Total.


IMO: 2nd gear pulls are easier, shorter, produce less heat and are bigger #'s

The above is all based using DynoJet248 Dyno and the Winpep7 Software.

[Billiumss]

Just use the VCM controls in the scanner to lock the transmission into 3rd gear, then you can lock the TCC. Once the dyno run is over unlock the TCC and deselect the 3rd gear on the VCM Control of the scanner. No need to go through all that trouble.


You would also have to modify your downshift tables:
Shift 0TPS%...100TPS%
2->1 0....................0
3->2 10..................10
4->3 20..................20

I tried using the VCM controls to "hold" 3rd gear and it still wants to down shift, I guess I'll have to make a program to hold it for me....

[Bill@HPTuners]

huh...i used it on my gtp with no problem ???

[12secSS]

I have noticed that the VCM controls sometimes do not work with certain vehicles. I once tried to lock the AFR to 12.9 on the dyno (with a wideband), but the car being scanned did not respond (stayed at 14.7). Yet my vehicles do, as verified by my wideband O2. ???

[chrisj6]

I am doing a dyno pull today to check out my Z06 cam #'s in my 5.3L truck, should I just let it shift on its own, thats what i did last time. Or is it better to do a 2nd gear pull.

Chris

[12secSS]

Use 3rd gear, unless you want to brag about inflatted numbers. What I would do is ... once the car is ready for a dyno run/pass, set the 3rd gear option on the VCM Scanner VCM controls to ON, Turn ON the TCC Solenoid. Make the pass/run and click off the TCC Solenoid option in the VCM Controls, then click off the 3rd gear option. This is the best way of dyno tuning/testing what you car has in terms of power. Plus by using the 3rd gear, you will be removing as many variables as possible to determine your HP numbers. Using 2nd gear actually multiplies the numbers from the engine, which causes them to be higher than normal (false bragging rights).

[mce]

this is the way i do it on my dyno
1= shift trans from nuetrel to 1st
2= open vcm controls,trans,a4 gear select
3= select 3rd , trans will then select 2nd by itself
4= this way i knowit will lock 3rd gear
5= shift into 3rd
6= now i can start my run

[redhardsupra]

this is the way i do it on my dyno
1= shift trans from nuetrel to 1st
2= open vcm controls,trans,a4 gear select
3= select 3rd , trans will then select 2nd by itself
4= this way i knowit will lock 3rd gear
5= shift into 3rd
6= now i can start my run

in 5 you mean shift as in with the lever or with the button controls?

[mce]

shift the gear lever.

i do it in this order that way i know VCM has taken control of the auto