Need trans tuning help

[Gregs]

I was wondering if someone could take a look at my tune. I've been working on getting the trans to kickdown when i want it to. I think i've got it about perfect, but i'm having problems at wot shifting now. The best way i can describe it is like a diesel when it defuels right before the shift. i have it set to shift at 6000 rpm but as soon as it hits 5800 rpm its like it pauses for a second then it shifts. During the pause the engine stops making power. anyone have any ideas?

[joecar]

What may be happening is that the throttle kickdown tables could be conflicting with the part throttle upshift tables...

see here: showthread.php?t=3336 (http://forum.efilive.com/showthread.php?t=3336)

The kickdown tables do not necessarily always override the PT shift tables...

Set the throttle kickdown tables to all 100%, and use the PT up/down shift tables to control PT downshifting, and use the WOT MPH/RPM tables to control WOT kickdown... you will find it much easier to do it this way.

Also, you may need to have a little more spread (say at least 5 mph difference) between the upshift and down shift tables for each gear (PT and WOT)... a difference of only 1 or 2 mph makes it easier for the PCM to be slow in deciding to shift.

[joecar]

From another unrelated thread:


sinr98,

I'm saying that your part throttle shifts may be occurring at different points than what is specified by the PT upshift tables D0901, D0902, D0903 and PT downshift tables D0906, D0907, D0908...

[ enter those table id's in uppercase in the Search box in the tunetool, that will take you right to the table ]

Most people don't notice... but some people run into this when they try to change the PT shift tables, they find that it doesn't shift at the points specified by the tables... or maybe that a large throttle downshift fails to occur.

this happens mainly because the kickdown ("downshift") tables dip down into the upshift portion of the PT upshift table... that is the shaded area shown in that other thread... the PCM is placed in a situation where two tables are specifying conflicting shift commands... either of the two tables may win (not necessarily the kickdown table)... this leaves the tuner wondering why the PT shift table is not being followed, or only being followed sometimes.

[ the throttle kickdown table is another form of PT downshift table... but it was supposed to be intended to be used at 100% throttle as the name of it implies ]

[Gregs]

sorry if i ask stupid questions or ramble a little bit, i'm a little new to this just trying to figure it all out. I checked to see if there was a conflict between the kickdown and part throttle shifting and i don't think there are any. I looked around and i'm guessing that the shift at rpm is the wot shift table? if so i have the 1>2 wot shift set at 6000. but i did notice that in the p/t shift for 100% throttle would equate to 5939 rpm. i checked my logs and the max rpm i got to was in the 5930-5945 range. So now i'm thinking the problem was that the truck was running the part throttle table and because that table commanded a shift before the wot shift point at 6000 that that was why i was having my problem. I did a little tweeking and i'll see how it goes.

Sorry to ramble on

[joecar]

No worries, ask all the questions you like... :cheers:

[Gregs]

figured it out... i'm an idiot... i had the rev limiter set at 5900 :doh2: