My biggest question when I started self-tuning with the twEECer was “where do I start???”. While I’m still no expert, I’ve messed around enough and read enough to feel fairly confident in a basic tuning workflow.
I’ll document below my entire tune from the very start and what and more importantly WHY I did what I did.
For a quick overview of my car’s mods, see the page about my ‘95 convertible.
First things first
You have GOT to make sure your car is mechanically sound, otherwise you are just tuning around problems that may get worse over time and degrade your tune leaving you to wonder what is going on.
Be sure you have done a recent tuneup and have checked each individual vaccum line for leaks.
Be sure set your timing at 10 degrees and your fuel pressure at 39 PSI.
What I datalog
I datalog the following:
- Actual Load
- Battery Voltage
- Injector Pulsewidth - DS & PS
- KAM Fuel Trim - DS/PS
- Lambda Commanded A/F - DS & PS
- MAF KG/hr
- MAF Voltage
- O2 sensor - DS & PS
- RPM
- Spark Advance
- Throttle Position Sensor
- Vehicle Speed sensor - MPH
- AFR from Wideband O2
The base tune
You’ll want to start off your tuning one of two ways.
The first way is to pull a reading of your stock car’s computer from the twEECer’s “Read EEC” button OR find a stock .BIN file for your car’s computer. The computer’s type is on a sticker on the EEC itself.
I have a U4P0 using the CBAZA strategy. Rather than trust that a .BIN file I download is completely stock, I started with a stock EEC reading that I did when I first got my twEECer.
Disable Checksum
Because we are modifying the stock EEC tune, the checksum built into the file will no longer be valid and will throw a code. Setting this to 0 will turn off the code.
Checksum Base Address = 0
Disable EGR
I do not have my EGR valve hooked up so I disable EGR in the computer.
EGR System Type = 2
Disable Thermactor (Air pump)
I do not have my airpump hooked up since I don’t have any cats so I disable it in the computer.
Thermactor Present = 0
Remove speed limiters
In the scalars I first shut off the speed limiters by doing the following:
speed_limit_stage-1_off = 16383
speed_limit_stage-1_on = 16383
180 degree thermostat
I have a 180 degree thermostat that opens sooner than the stock thermostat. I have the fans come on a bit earlier than stock to work with the thermostat and keep things cool.
fan_high_speed_ECT1_on = 196
fan_high_speed_ECT2_on = 200
fan_high_speed_ECT_off = 190
fan_low_speed_ECT_off = 182
fan_low_speed_ECT_on = 188
Longtubes
These settings are under debate as to how much value they add. I’ve had success running them so I leave them there.
When you add longtube headers you are moving the O2 sensors further away from the combustion chamber than stock. These settings lengthen the time the computer waits to look for the results of each combustion cycle.
R P M
900 1300 1500
.075 - 24 24 24 24
L .06- 24 24 24 24
O .05 - 20 20 20 20
A .04 - 20 20 20 20
D .03 - 20 20 20 20
.02 - 20 20 20 20
.01 - 20 20 20 20
.005 - 20 20 20 20
4R70W Automatic Transmission
I ditched the stock AODE transmission in favor of an AODE case with J-modded 4R70W internals. The 4R70W is an AODE with tougher parts and wider ratio gearing.
I borrowed most of these settings from a tune written by Jerry for the W4H0 (Jerry created the J-mod)
To adjust for the wider ratio 4R70W
trans_gear_ratio_1 = 2.84
trans_gear_ratio_2 = 1.55
trans_gear_ratio_3 = 1
trans_gear_ratio_4 = .7
To keep WOT 3 - 4 shifts from happening
trans_wot_shift_34 = 7000
The maximum speed that the EEC will allow a 2 to 1 shift
trans_2-1_pullin_max_speed = 40
Modify the 3 to 4 shift just a bit by dropping the pressure slightly and reducing the shifting delay
trans_TV_adder_34 = 12
trans_TV_adder_34_time = .5
??? - riding on Jerry’s knowledge here
trans_mnossper = 0
trans_dnshft_slptrgr_hld_dur_2 = .25
trans_clthrtl_unlk_dly_uncnd = 3
trans_min_TP_for_torque_mod = 900
Adjust the transmission’s shifting for my 4.10 gearing
trans_shift_schedule_12
X 0 0 152 200 252 332 500 668 668 1020
Y 13.5 13.5 13.5 23 35 43 50 51 70 70
trans_shift_schedule_21
X 0 0 0 0 152 300 452 724 724 1020
Y 8.5 8.5 8.5 8.5 8.5 10 27 35 35 35
trans_shift_schedule_23
X 0 0 0 100 200 332 500 668 668 1020
Y 24 24 24 24 50 68 70 70 70 70
trans_shift_schedule_32
X 0 0 0 0 352 400 452 724 724 1020
Y 21 21 21 21 21 45 55 65 70 70
trans_shift_schedule_43
X 0 0 0 0 252 276 400 668 668 1020
Y 27 27 27 27 27 55 90 107 112 112
trans_shift_schedule_34
X 0 0 0 100 252 332 500 668 668 1020
Y 40 40 40 40 94 103 112 127.5 127.5 127.5
These tables control when the convertor locks. I am told by Don of LaSota racing that the convertor should be locked shortly after the shift for best performance
trans_converter_lock_2nd
X 0 0 0 0 0 0 0 200 252 1020
Y 99 99 99 99 99 99 99 30 30 30
trans_converter_unlock_2nd
X 0 0 0 0 0 0 0 252 276 1020
Y 95 95 95 95 95 95 95 95 25 25
trans_converter_lock_3rd
X 0 0 0 100 252 332 500 668 668 1020
Y 40 40 40 40 94 103 112 117 127 127
trans_converter_unlock_3rd
X 0 0 0 0 0 0 0 176 236 1020
Y 35 35 35 35 35 35 35 35 39 39
trans_converter_lock_4th
X 0 0 0 0 0 160 200 276 352 1020
Y 41 41 41 41 41 41 65 90 102 102
trans_converter_slip_2nd
Entire table 0
trans_converter_slip_3rd
Entire table 0
trans_TV_pressure_12
X 0 0 0 0 0 52 400 600 1020
Y 21 21 21 21 21 25 25 99 99
trans_TV_pressure_21
X 0 0 0 0 0 0 0 0 1020
Y 0 0 0 0 0 0 0 0 0
trans_TV_pressure_23
X 0 0 0 28 52 252 400 600 1020
Y 20 20 20 20 20 35 35 99 99
trans_TV_pressure_32
X 0 0 0 0 0 0 352 352 1020
Y 0 0 0 0 0 0 0 30 30
