endo
July 5th, 2009, 10:43 PM
This has always bugged me about my truck, but I'm not sure if it can be tuned out of it...
When driving my truck in hilly areas with cruise control, i find it a bit too willing to grab 2nd gear in situations where it shouldn't. The scenario starts with the truck on a relatively shallow grade in 4th, at say 55mph/90kph The grade steepens, the truck begins to lose speed. The cruise increases throttle position, and the trans kicks down to 3rd. The truck begins to gain speed. The cruise continues ramping in throttle all the way up to 100% indicated TP, causing the trans to select 2nd. It goes PE (timer is zeroed), hits target speed almost instantly (it was already within 1mph) and drops it back in third, where it remains until the top of the hill.
It's always done this, even when bone-stock (albeit it probably didn't go PE then).
I don't see any parameters to cap TP% or adjust rate of change of TP% for cruise.
I don't think D0907 (Part throttle 3->2 Shift Speeds) and D0961 (Throttle Kickdown, 3->2) are going to help. While both of those tables have cruise-specific settings, the cruise is commanding WOT which means open-loop instantly on my truck.
Any suggestions on this, or might the above mentioned tables fix it (haven't actually tried changing them to correct it yet)? I really want cruise control to drive in a Grandma-approved fashion. Tired of explaining to passengers "no, that's the cruise control, it's angry!"
When driving my truck in hilly areas with cruise control, i find it a bit too willing to grab 2nd gear in situations where it shouldn't. The scenario starts with the truck on a relatively shallow grade in 4th, at say 55mph/90kph The grade steepens, the truck begins to lose speed. The cruise increases throttle position, and the trans kicks down to 3rd. The truck begins to gain speed. The cruise continues ramping in throttle all the way up to 100% indicated TP, causing the trans to select 2nd. It goes PE (timer is zeroed), hits target speed almost instantly (it was already within 1mph) and drops it back in third, where it remains until the top of the hill.
It's always done this, even when bone-stock (albeit it probably didn't go PE then).
I don't see any parameters to cap TP% or adjust rate of change of TP% for cruise.
I don't think D0907 (Part throttle 3->2 Shift Speeds) and D0961 (Throttle Kickdown, 3->2) are going to help. While both of those tables have cruise-specific settings, the cruise is commanding WOT which means open-loop instantly on my truck.
Any suggestions on this, or might the above mentioned tables fix it (haven't actually tried changing them to correct it yet)? I really want cruise control to drive in a Grandma-approved fashion. Tired of explaining to passengers "no, that's the cruise control, it's angry!"