3 Attachment(s)
Cruze 1.4 Automatic Transmission Tuning
Hi! Just wanted to do a quick write on my recent tuning of my Cruze's Transmission. I have not yet modified my Engine's Tune as I am still researching/planning the process of tuning the E78 ECM.
Anyways! Here's my write up on modifying the "Part Throttle Shift" "Normal" Table in VCM Editor under "Transmission".
VCM Editor: Trans > Auto Shift Speed > Part Throttle Shift > Normal
My main goal in modifying this table was to ensure that the accuracy and responsiveness of my shift points were set to deliver maximum power/driveablitly across all ranges of speed (Whether that be a WOT pass, Traffic Cruising, or Highway Driving). I am happy to say that I have achieved my goal and have had a ton of fun learning/making the modifications ;) .
Here is my Cruze's stock Normal Shift Table:
Attachment 55706
As you can see the shiftpoints are set all over the place in regards to Speed/Throttle Position. While this may be good for economy, it isn't good for me, and when I step on the pedal (With my Stock Tune) I definitely don't get the responsiveness in which I would like to receive. I am sure that many out there can agree with me that own a stock Cruze.
So in order to get from Point A (Stock) to B (Modified) I did the following, and I hope some of these tips help anybody out messing with this table:
1. Using the Manual Shift Mode, I drove around and found the Max Potential of Speed for Each Gear (Ex. In First Gear, I was able to wind it out to around 16MPH while not going overboard with RPM and still making applicable power). I did this for 1st, 2nd, 3rd, and 4th gear. 5th and 6th Gear have there own tables, I did not find the need to mess with these tables.
2. After recording the max MPH potential for each gear I did some driving around and testing to find a good Throttle Position Percentage to allow the trans to shift either up or down. As you can see in my finished modified table at the bottom of this post the Shift MPH Point stays the same after 44% Throttle Position. I found that this worked best for me because I can still stay in higher gears when I am in traffic, but when I want to take off and accelerate all I have to do is apply more pedal then the trans will shift through the gears at the set ranges.
3. Then I went into my stock tune file and copied the speed at 0% Throttle position into my modified tune for each gear. After that I copied that speed for each gear all the way up to 44% TP. Now that I had the base speeds for under 44% TP Crusing, it was time to smooth out the transition from Cruising to Acceleration!
4. This is the fun part because using the 2D Chart View, you can see that there is an instant Drop off between Shift MPH Speeds below 44% TP. We need to smooth this out for better transition while driving around. This part is pretty easy and predictable as you just have to drag each point on the 2D Graph to provide a smooth stepped transition between shift speeds (Compare the Table below to the Final Completed Table)
Attachment 55708
5. One thing that I failed to note above was finding out what speed was best to set the downshifts to. I basically subtracted around 4MPH from the original upshift speed and used them for my downshift speeds for 44% TP and above. I may have adjusted them slightly after driving around, but performed the same smoothing process on them as well.
6. Here is the final Product after driving around and making sure all of my corrections to this table were driveable/accurate! This was a ton of fun and a huge learning experience as this was my first time making Trans changes in the VCM Editor. Hope that this post was helpful to anybody modifying the same table on their Cruze!
Final Table:
Attachment 55707
