Hi, I'll try to answer that, but it would be better if I knew what car and what mods.
All the tunes are similar in the respect that they optimize the calibration for overall driveability, throttle response, raise rev limiter slightly, remove speed limiter, get rid of torque truncation in 1st gear on 4.0Ls, optimize torque reduction on autos, firm up shifts on autos, change shift/lock points on autos, and the A/F ratio is optimized at WOT.
The 87 tune does not result in a ton of power, but you still get all the benefits above. On 89 we can run a little more timing and get a little more power. Premium fuel (91-93) is going to get you the most power and torque due to the ability to run more timing.
The mileage tunes increase fuel economy while cruising, with no loss in wot power. Some may notice a little bit of reduced part throttle power with the mileage tunes.
For example, on an automatic 4.0L I optimize the shift/lock schedule, so even with a 93 perf tune you will pick up a slight amount of mileage due to the improved efficiency through the trans.
Hi, I'll try to answer that, but it would be better if I knew what car and what mods.
All the tunes are similar in the respect that they optimize the calibration for overall driveability, throttle response, raise rev limiter slightly, remove speed limiter, get rid of torque truncation in 1st gear on 4.0Ls, optimize torque reduction on autos, firm up shifts on autos, change shift/lock points on autos, and the A/F ratio is optimized at WOT.
The 87 tune does not result in a ton of power, but you still get all the benefits above. On 89 we can run a little more timing and get a little more power. Premium fuel (91-93) is going to get you the most power and torque due to the ability to run more timing.
The mileage tunes increase fuel economy while cruising, with no loss in wot power. Some may notice a little bit of reduced part throttle power with the mileage tunes.
For example, on an automatic 4.0L I optimize the shift/lock schedule, so even with a 93 perf tune you will pick up a slight amount of mileage due to the improved efficiency through the trans.
I am curious about what "torque truncation" in first gear refers to. And does this apply to a 2007 4.0 manual transmission - or just automatics ?
Torque is limited by the PCM in 1st gear to keep the 7.5 axle from seeing too much torque. Just manuals.
Other than with some real abusive driving would turning off the torque truncation cause any problems for the 7.5 axle ?
Sometimes my mustang seems to want to buck or stall when taking off from dead stop. Seems to maybe be a little worse after getting off the freeway or in stop and go traffic. Never had this problem with my 1999 Ranger or other manual transmission vehicles.
I wonder if maybe torque truncation could have something to do with this ?
< Message edited by Frank Bullitt -- 4/24/2008 6:27:44 PM >
Printable Version
87/89/91 - 
