I recently swapped a 4bt Cummins Diesel into my cruiser utilizing the stock auto transmission and OEM computer. The computer controls the engine and transmission and was worried about it functioning without the engine inputs.
It is installed and tuned with 90-95% of where I want it so I thought I would document my findings and methods I have about 180 miles on an original 230k transmission and feels great.
Valve Body/rail pressure:
I had the trans rail pressure set to ramp up quick and firm as well as the 3rd setting internal with a TransGo “truck setting valve body modification which is suppose to increase pressure and flow for more clutch holding power and cooling affects.
Torque converter:
I was planning on running it stock but broke the input pilot off not paying attention so I sent it off to a shop the tightened the fins for lower lock up. From what I could find the stock was around 2000rpm stall. There are not billet options and was told they could lower it a few 100 with fin adjustment. So 1700'ish stall. It's not an exact science but based on feel it didn't change much from stock but that was with a different engine so it's hard to tell.
Wiring:
basically using the Factory WD for the tranny I made sure to include all those inputs. The EGR temp sensor I replaced with a 10k ohm resister which should represent a functioning sensor once warm. I unplugged it after about 150 miles and have not noticed a difference. I also made sure to use all 3 original engine temp sensors, one is specific to the trans control. During installation I broke the connector off this sensor and it has not seemed to affect the function or shift. I do plan on adding it as I have a replacement but it doesn't seem necessary.
TPS: (discussed in a % based on scan gauge output)
I made a bracket that would give me a bunch of flexibility for adjustment. It would give em rotational change and pivot point. This gave me the ability to adjust total TSP swing as wells a cam affect both on the low side and high side. I haven't adjusted to every possible potential but made large swing changes in the first 20-30 miles to get in the ball park of what felt right and will get into details of the fine tuning.
TC lock-up:
OD off TC lock up at 43mph
OD on TC lock up at 55mph
TC will unlock with 35% plus of TPS input
Shift:
my best guess is there is a table to speed and TPS input that controls shift points.
With a TSP 0- full trottle range observations:
0-70% will not shift
0-20% shift very quickly as it thinks your moving very fast with very little input will shift into OD at 30mph
Idle switch is of at 12.5-14% when idle switch is engaged it wants to coast and not be engaged.
range: 11.5-70% quicker ratio high %
cruise: 30-40% (45mph-65mph)
to get it to shift I would have to let off the gas to the 15-25% range based on speed to get it to shift. The slower moving the lower amount of TPS% for shift point.
On highway down shift wants to occur at 55-65% (helpful for some engine swaps but with a diesel you never want an down shift)
range: 10-50% mild ratio high %
cruise 20-30% (45mph-65mph)
drive ability was much better but still had to drive like a manual lifting to let it shift. At 50mph TC would unlock at 30-35% higher at higher ratio
range 10.5-40% pretty linear with throttle.
cruise: 18-30% (45mph-65mph)
very drivable. Steady input with comfortable shifts. more throttle firm shift at higher rpm under hard acceleration slight lift of the foot allows shifts boost drops about 5psi during this time. With very little input 1-2 shift are very quick 5mph will hold to ~15 mph with more peddle input but will shift hard and firm. TC lockup as expected and OD as expected. No OD TC unlock noticed yet up through 80mph.
This set up is where I will start fine tuning with more miles and each adjustment for more indepth observations.
Other observation:
OD: will shift below the 45MPH mark with TPS under 20% otherwise at the 45mph mark.
PWR Button: turns it into more of the manual shift feel letting off 5-10% TPS for shifts. Will be very nice for hills and towing to really have good control with out having to manually use the shifter. All from the foot control.
These are my observations as of now. I plan on putting a TC lockup switch/indicator light so I can confirm that I am not having it unlock when I don't want it to. I am confident I can get the setup to lock up when I want without having to mess with a switch for the sake that anyone could jump in it. The goal is feel confident that my wife can get in it and drive cross country.
I will update as I notice new things or firm up my numbers as I am not taking data point to figure out the exact TPS/speed but believe this will help people considering a swap and help in deciding if a stand alone is needed/necessary.
It is installed and tuned with 90-95% of where I want it so I thought I would document my findings and methods I have about 180 miles on an original 230k transmission and feels great.
Valve Body/rail pressure:
I had the trans rail pressure set to ramp up quick and firm as well as the 3rd setting internal with a TransGo “truck setting valve body modification which is suppose to increase pressure and flow for more clutch holding power and cooling affects.
Torque converter:
I was planning on running it stock but broke the input pilot off not paying attention so I sent it off to a shop the tightened the fins for lower lock up. From what I could find the stock was around 2000rpm stall. There are not billet options and was told they could lower it a few 100 with fin adjustment. So 1700'ish stall. It's not an exact science but based on feel it didn't change much from stock but that was with a different engine so it's hard to tell.
Wiring:
basically using the Factory WD for the tranny I made sure to include all those inputs. The EGR temp sensor I replaced with a 10k ohm resister which should represent a functioning sensor once warm. I unplugged it after about 150 miles and have not noticed a difference. I also made sure to use all 3 original engine temp sensors, one is specific to the trans control. During installation I broke the connector off this sensor and it has not seemed to affect the function or shift. I do plan on adding it as I have a replacement but it doesn't seem necessary.
TPS: (discussed in a % based on scan gauge output)
I made a bracket that would give me a bunch of flexibility for adjustment. It would give em rotational change and pivot point. This gave me the ability to adjust total TSP swing as wells a cam affect both on the low side and high side. I haven't adjusted to every possible potential but made large swing changes in the first 20-30 miles to get in the ball park of what felt right and will get into details of the fine tuning.
TC lock-up:
OD off TC lock up at 43mph
OD on TC lock up at 55mph
TC will unlock with 35% plus of TPS input
Shift:
my best guess is there is a table to speed and TPS input that controls shift points.
With a TSP 0- full trottle range observations:
0-70% will not shift
0-20% shift very quickly as it thinks your moving very fast with very little input will shift into OD at 30mph
Idle switch is of at 12.5-14% when idle switch is engaged it wants to coast and not be engaged.
range: 11.5-70% quicker ratio high %
cruise: 30-40% (45mph-65mph)
to get it to shift I would have to let off the gas to the 15-25% range based on speed to get it to shift. The slower moving the lower amount of TPS% for shift point.
On highway down shift wants to occur at 55-65% (helpful for some engine swaps but with a diesel you never want an down shift)
range: 10-50% mild ratio high %
cruise 20-30% (45mph-65mph)
drive ability was much better but still had to drive like a manual lifting to let it shift. At 50mph TC would unlock at 30-35% higher at higher ratio
range 10.5-40% pretty linear with throttle.
cruise: 18-30% (45mph-65mph)
very drivable. Steady input with comfortable shifts. more throttle firm shift at higher rpm under hard acceleration slight lift of the foot allows shifts boost drops about 5psi during this time. With very little input 1-2 shift are very quick 5mph will hold to ~15 mph with more peddle input but will shift hard and firm. TC lockup as expected and OD as expected. No OD TC unlock noticed yet up through 80mph.
This set up is where I will start fine tuning with more miles and each adjustment for more indepth observations.
Other observation:
OD: will shift below the 45MPH mark with TPS under 20% otherwise at the 45mph mark.
PWR Button: turns it into more of the manual shift feel letting off 5-10% TPS for shifts. Will be very nice for hills and towing to really have good control with out having to manually use the shifter. All from the foot control.
These are my observations as of now. I plan on putting a TC lockup switch/indicator light so I can confirm that I am not having it unlock when I don't want it to. I am confident I can get the setup to lock up when I want without having to mess with a switch for the sake that anyone could jump in it. The goal is feel confident that my wife can get in it and drive cross country.
I will update as I notice new things or firm up my numbers as I am not taking data point to figure out the exact TPS/speed but believe this will help people considering a swap and help in deciding if a stand alone is needed/necessary.
