I know upshift MPH has to remain higher than downshift MPH, but I was wondering if the "spread" has to be in a certain percentage or not?

In other words, if you set WOT upshift for 2>3 at 70 MPH, how close can you "safely" have the WOT downshift MPH set? Is the desired spread by percentage or just as long as downshift is lower, then that's all that matters?

I'm trying to eliminate, or at least reduce, the dead powerless area in my 2002 Silverado when trying to merge onto a highway and I'm going just slightly faster than my current downshift MPH. I also lowered my A/C cutoff rpm from 5250 to 3250rpms to help as well.

 

What you want to do is make a log from 0 to about 100 or so. Read back through the log to thee highest rpm that you'd want a kickdown to achieve. Read the speed that it occurs at and set that to be your downshift from the gear up. Example

Common Silverado with 4.10 gear and 30.7" tire settings.

41mph 1-2
76mph 2-3
128mph 3-4
37mph 2-1
67mph 3-2
120mph 4-3

 

Thanks for the tips.

I actually re-did my WOT upshift MPH settings from a previous datalog and dead area was no different. What I failed to realize was that my 2>3 upshift datalogged MPH was only at 4700 rpm's (72mph)...lol. It appears I let off the gas right before shift.
That made my 2>3 shift MPH setting of 70mph way too low as far as calculating a decent downshift MPH...

Going by the numbers above, and knowing I have 373's, I'd assume I can MPH higher than 76, but keeping it within reason I went with 77mph up and 73mph down. I'll know tomorrow morning on drive to work whether that cures the dead spot in the 60-65mph area...

 

I think around 4 mph difference in the two. Other wise some computer cofusion can occur, from what ive read. Same goes with the tc stuff. Heres a spreadsheet that help visualize the speeds, put them on the same page.



http://forum.efilive.com/showthread.php?t=5876

 

Thanks. I appreciate the help from everyone who's replied.

 

I usually do 5mph or 500 rpm...

 

UPDATE...

My new upshift/downshift settings seem to work very well. There is absolutely no more dead powerless area in the 65 MPH range whatsoever...

WOT shift MPH
1 -> 2 shift = 43
2 -> 3 shift = 76
3 -> 4 shift = 255 (in other words it will not upshift into OD at WOT)

2 -> 1 shift = 39
3 -> 2 shift = 72
4 -> 3 shift = 237

WOT shift RPM
1 -> 2 shift = 5900
2 -> 3 shift = 5800
3 -> 4 shift = 5600


Actual shift MPH is roughly 46 mph on the 1 -> 2, and about 84 mph on the 2 -> 3 shift.
UpShift RPM is dead on.

This is 2002 5.3 liter Chevrolet Silverado.

Mods:
Custom Flowmaster "dual" catback
Modified stock airbox and mounting plate
Fram Airhog air filter
Airaid air intake tube
HPTuners tuning software

Thanks for the replies everyone.

 

How important (or not) is it for the partial throttle tables 100%TPS speeds to match the WOT speed table?

 

I hope it isn't/wasn't important because neither my truck, or my car's PT and WOT settings are anywhere close to one another.

Even 100% untouched stock, my truck's numbers didn't match. I guess you could always enter the WOT MPH numbers into the PT 100% TPS boxes, and simply let the software "smooth" the graphs...Hopefully, one of the more knowledgeable tuners will weigh in on that one though.

BTW, Congrats on new best ET!