Holding 4th gear for Dyno

[Matt68]

I started playing around with my truck tonight on the dyno and could not get it to stay in 4th gear. I don't have much experience with autos so I have been trying to read up as much as I can. Here is what I tried:
1. Tried using the DVT in the scan tool and locking it in 4th - still downshifted
2. Tried to lock the TCC in the DVT - Error message that the trans must be in neutral
3. Used Tow/Haul mode - still downshifted
**All of these were tried with the trans in the manual shifting mode. Does this need to be in Drive for the DVT settings to work????

Looking at my log, it looked like the first downshift from 4->3 was at 41 MPH which matched up with the values in table {D1001} I tried adjusting them for all gears up to 100MPH to try and keep it from downshifting. Still downshifted:doh2:

Are there any suggestions on what needs to be changed? Ideally I would like to do it with the scantool only so I wouldn't have to license a vehicle everytime I want to put a vehicle on the dyno.

Also, is there a way to log what gear you are in? I searched the PID's and could not find a way to log this. With all the shifting it was doing, it was hard to tell what gear I was in half the time. The TUTD feature would not always put it in the gear I wanted:throw:

Thanks,
Matt

[joecar]

Try logging GM.GEAR and GM.TCCMODE.

[Matt68]

I saw those, but each of them are shown as unsupported PID's.

[joecar]

Those will still log.

[Matt68]

Those will still log.

Tried logging those and no data. Also tried GM.gearsel and State00. With no luck.

Tried some more test with the trans in D and trying to hold it in gear with the DVT. No luck. Then tried to change setting for the Normal, Pattern A, Pattern B, and TUTD Shift speeds for all of the down shift values to 318MPH to try and keep it from downshifting. I also changed the WOT shift speeds for any downshift to 318MPH.

Once I loaded it back in the truck seemed to rev really high before it shifted (if it shifted at all). Once I did get it 4th with the manual shift it would run up to 3000RPM, then downshift into 1st and jump up to 5700RPM. I don't see how the changes I made would cause it to do this.

Here are a couple of screen shots showing what I changed.
10946
10947

[joecar]

It might be downshifting to 1st because the downshift mph is being met (i.e VSS is below 318 mph)... you might try setting it to zero.

[joecar]

i.e. to inhibit an upshift set its mph to max, to inhibit a downshift set its mph to min.

[Matt68]

I see. Any ideas on the PID's?

I went out again and messed around with it. Loaded the stock program back in and just eased into the throttle until a higher RPM. I was trying to go from 2500 up, and this time when from about 3000up. Ran fine as long as I fed the throttle in from about 2000 up until 3000.

If I get a chance I will try setting them to 0 and see what that does.

Currently 273HP and 300Tq to the wheels.

I need to some more reading on the E38's. Getting some KR with stock tune and I don't like the delay in the PE enable. Also seem to lose some data during the run. I have 24 channels logged, and I am losing data from 3K to 5K RPM (2sec)

[joecar]

I don't know why DVT won't hold a gear.

[Tre-Cool]

when dyno tuning my commodore. (g8) i use sports/manual mode and just tap it to the gear i require.

from the looks of the pictures you posted. you have gone the wrong way.

you need the 4->3 values etc to be below the speed you want it to down change at for the 0-100% tps ranges.
Example:

LABELS Gear Change
TPS . 1->2 2->3 3->4 4->5 5->6 2->1 3->2 4->3 5->4 6->5
0.00 65.000000 115.000000 181.000000 245.000000 511.000000 11.000000 25.000000 45.000000 50.000000 56.000000
6.25 65.000000 115.000000 181.000000 245.000000 511.000000 11.000000 25.000000 45.000000 50.000000 56.000000
12.50 65.000000 115.000000 181.000000 245.000000 511.000000 11.000000 25.000000 45.000000 50.000000 56.000000
18.75 65.000000 115.000000 181.000000 245.000000 511.000000 11.000000 25.000000 45.000000 50.000000 56.000000
25.00 65.000000 115.000000 181.000000 245.000000 511.000000 11.000000 25.000000 45.000000 50.000000 56.000000
31.25 65.000000 115.000000 181.000000 245.000000 511.000000 11.000000 25.000000 45.000000 50.000000 56.000000
37.50 65.000000 115.000000 181.000000 245.000000 511.000000 11.000000 25.000000 45.000000 50.000000 56.000000
43.75 65.000000 115.000000 181.000000 245.000000 511.000000 11.000000 25.000000 45.000000 50.000000 56.000000
50.00 65.000000 115.000000 181.000000 245.000000 511.000000 11.000000 25.000000 45.000000 50.000000 56.000000
56.25 65.000000 115.000000 181.000000 245.000000 511.000000 11.000000 25.000000 45.000000 50.000000 56.000000
62.50 65.000000 115.000000 181.000000 245.000000 511.000000 11.000000 25.000000 45.000000 50.000000 56.000000
68.75 65.000000 115.000000 181.000000 245.000000 511.000000 11.000000 25.000000 45.000000 50.000000 56.000000
75.00 65.000000 115.000000 181.000000 245.000000 511.000000 11.000000 25.000000 45.000000 50.000000 56.000000
81.25 65.000000 115.000000 181.000000 245.000000 511.000000 11.000000 25.000000 45.000000 50.000000 56.000000
87.50 65.000000 115.000000 181.000000 245.000000 511.000000 11.000000 25.000000 45.000000 50.000000 56.000000
93.75 65.000000 115.000000 181.000000 245.000000 511.000000 11.000000 25.000000 45.000000 50.000000 56.000000
100.00 65.000000 115.000000 181.000000 245.000000 511.000000 11.000000 25.000000 45.000000 50.000000 56.000000

bare in mind these are KPH values.

what is interesting with the 6l80 is that the upshift values in tapup/tap down mean almost nothing. the down shifts have more control as to what gear the trans will go into when trying to drive it "manually".

[Matt68]

Now that I look at it (and think about it) your right, I did go the wrong way.

Thanks for the input!
Matt

[minytrker]

I used to flash in changes to dyno auto's but the for the last few years I have just used the scan tool and hold it in gear. What year and make are you doing this on?