Upshift issues at track

core-rider

core-rider

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Took my truck to the track for the first time this past weekend on the new setup and had some issues I couldn't figure out with the transmission upshifts I'm hoping the brain-trust here might be able to help me with. My truck didn't want to shift under full load for the 1-2 and 2-3. It would only shift if I briefly chopped throttle. I have my shift points set at 5000, but maybe that's not where I should be looking. Q1 pass was a bust because I pushed through the lights foot braking and red lit, so I just cruised down. Q2 log showed 5600+ 1-2 before I chopped and it shifted, got back into it and did same thing 2-3 at lower RPM. Went to open area in parking lot right after that pass and it did perfect so I thought it was just a weird anomaly.

Went back for Q3 and same thing happened, so I took a look over the tune and didn't see anything wrong in my limited understanding of the PxS settings. Talked with a guy in a Camaro running Holley and he suggested lowering shift points down 400rpm, so I did that. In staging lanes I made a last second choice to lower rev limiter from 6000 to 5300 because I didn't want to hurt anything and it needed to be lower anyway. Still didn't shift when it should have, but because it hit limiter it dropped power enough to shift.

I've never had this issue on the street, so only thing I can think of is more load on a tire and sticky track??? Like I said in the parking lot right after the 1st pass it did perfect. I'm attaching logs and tune for y'all to look over... Any help is appreciated! I'm also going to post on Stinger forums, but I feel like we have more understanding on the E4OD here.

Engine tune

Trans tune

Q2 log

Q3 log

E1 log
 
So, without seeing your tune, here's my comments based on the behavior:

In "Shift Delays and Max RPMs" set the Max RPMs to be roughly the same as your 100% throttle upshift RPMs (takes a little math because the curves use MPH, I use a spreadsheet for all my up/downshifts that I'm happy to share). Make sure your 100% throttle upshift RPMs will be roughly the same as your Max RPM settings.

In Shift Settings, make sure "Predictive Up-shifting" is "On."

Mine shifts within 50 RPMs of the set point pretty much every time setup like that.

Also it's worth noting that if your 85% throttle and 100% throttle upshift points are different, you may not actually be hitting WOT on the street. I have a tendency to not actually get my foot all the way to the floor in the red truck because of the way the boost comes on.

If your rev limiter is set too low, you'll never hit the RPM/MPH thresholds for upshifts.
 
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Yes please share that spreadsheet if you don't mind. I'll look over those settings... thank you!
 
These are the shift points I use in the white truck. The yellow-highlighted cells in the upper left (Load and MPH) are the ones you change, the rest are calculated. The second tab has everything laid out so that you can copy paste it into TunerStudio. The graph helps to make sure you don't "cross the streams" because if you do, bad things happen. Actually it just confuses the ECU and shifting gets all nutty.

Load1 Up2 Dn2 Up3 Dn3 Up4 Dn
85​
5229​
4357​
5235​
4457​
5237​
4456​
100​
5229​
4357​
5235​
4457​
5237​
4456​

The bold values above are my calculated upshift RPMs from gear ratios, diff ratio, and tire diameter. My Max RPM upshifts are 5200 in 1st and 5300 in the other gears.

There's a couple other tables patched in on the first page, but it's just various things I've looked at over time while trying to work on the transmission feel. The main things are the two tables on the left and the graph.
 

Attachments

  • Shift Points White Truck.zip
    27.1 KB · Views: 2
Without digging too deep:
  • Set your tire diameter to match what's on your truck.
  • Turn on predictive up-shifting.
  • My shift curves are way more aggressive than yours, but I like a very responsive reaction - meaning when I dig into the throttle more than ~30%, I want the downshift. With the turbo, you may be perfectly happy where you are. With the red truck, it downshifts quickly, but upshifts at lower throttle angles than the white truck. I like the downshift to wake the turbo up, but once it's up, I don't feel like I need a lot of RPMs before the upshift.
 
FMOS Racing said:
Without digging too deep:
  • Set your tire diameter to match what's on your truck.
  • Turn on predictive up-shifting.
  • My shift curves are way more aggressive than yours, but I like a very responsive reaction - meaning when I dig into the throttle more than ~30%, I want the downshift. With the turbo, you may be perfectly happy where you are. With the red truck, it downshifts quickly, but upshifts at lower throttle angles than the white truck. I like the downshift to wake the turbo up, but once it's up, I don't feel like I need a lot of RPMs before the upshift.
Click to expand...
So for street driving I've had to manipulate the tire diameter to try and get my TS speed to match dash speed and GPS speed. My street tire is a 255/50/17 which is 27.8" IIRC. Drag setup is 305/45/17 which is 28.2 I think. I've gotten to within 2mph low in TS with the street setup with 30" tire size in the tune. I'm saying all this because maybe that has something to do with all this. Maybe I need to stop making my TS speed match my dash/GPS speed quite so accurately and concentrate on the TS speed being setup correctly for the shift points and not care so much about how close it matches dash/GPS. For reference my dash is within 1mph of GPS on my phone.

I also made note that my final pass the log showed 99mph before a let off, but trap speed for the pass was 106mph. Basically I'm not sure what is more accurate... just want it to shift correctly so I can make better/faster passes! ;)
 
I had sort of a similar problem and predictive upshift setting Jeff recommends did the trick. I couldn't see your logs (permissions) but did see the trans tune and that is the only thing I could see.

I also have a dumb theory that some of thee trans settings need a key off / key on to work and don't prompt you - since I know I've made adjustments while driving that didn't seem to take until the next time I drove and the change was there. It may also be me doing something weird, dunno.
 
Trap speed is based on time taken to trip two beams at the end of the track. Your logged mph should always be higher if you're still accelerating.

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From the log it looks like the sol didn't trigger until 5359rpm from a 5000rpm commanded which seems reasonable, but then add in time for all that transmission voodoo to make the shift actually happen it most likely would have shifted at 5718rpm.

so -718rpm from what you want and I'd be curious to see. It may just be a time thing, which is why predictive should lend a hand to get closer.
 
Required said:
From the log it looks like the sol didn't trigger until 5359rpm from a 5000rpm commanded which seems reasonable, but then add in time for all that transmission voodoo to make the shift actually happen it most likely would have shifted at 5718rpm.

so -718rpm from what you want and I'd be curious to see. It may just be a time thing, which is why predictive should lend a hand to get closer.
Click to expand...

This is EXACTLY how to approach shift points. The closer the trans is to stock the longer you need to give it to shift. So like mentioned dial back the points until the shift happens at the RPM point you want. You'll probably end up making at least two tunes to accommodate for the stickier surface of the tires and the track vs the street with street tires.
 
Ah, I just checked my last 1/4 mile pass and logs say .801 second per shift between commanded and actual for 1-2 and 2-3. I’m running 3000 stall and punisher other then that it’s stock AFAIK.


So yeah, that’s a long time since you gained 628rpm in .534 seconds.
 
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Well, sounds like I have some changes to make then... thanks for all the insight so far guys!
 
That's the kind of lump the predictive upshifting will line out.

I have found that, in the red truck, I need to set the 1-2 shift a little lower RPM-wise than what I actually want, or it'll overshoot by a few hundred RPMs. The rate of the RPM increase must be a little too fast for the processor + transmission solenoids.
 
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I know my truck will shift almost dead on every time. And that was with probably over 800hp at the time. The best way to do it is to match your shift MPH with your shift RPM alongside predictive upshifting. I use Wallace racing to determine the speed my truck will be going at a certain rpm and plug that into my tune.

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To be fair though I have a stage 3 A1 trans as well so I'm sure that helps with getting shifts off quickly.

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Raymond_B said:
LOL yeah, gigantic difference
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Lol. I know back when I had the NOVI 2k and stock ECU I was trying to get into the 6's in the 1/8th and I had to command shift points like 2000 rpm early to get anything close. Was a nightmare. Wish I had the A1 trans back then.

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slow94 said:
Lol. I know back when I had the NOVI 2k and stock ECU I was trying to get into the 6's in the 1/8th and I had to command shift points like 2000 rpm early to get anything close. Was a nightmare. Wish I had the A1 trans back then.

Sent from my Pixel 6 Pro using Tapatalk
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Yeah mine is set to 1-2 shift at 4500 and it still bumps the rev limiter at 5600 if it loses traction and RPMs climb faster. It still beats manually shifting that beast tho.
 
Ah the good ol days with the manual valve body C6... And the stock column shifter. Fun times!

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FMOS Racing said:
Ah the good ol days with the manual valve body C6... And the stock column shifter. Fun times!

Sent from my motorola edge plus 5G UW (2022) using Tapatalk
Click to expand...
Sometimes I think a full reverse manual valve body with transbrake would be the way to go. Transbrake at least would be nice for the turbos.

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