Can cold weather screw up transmission settings?

[jcbst12]

After trial and error I found a good setup for transmission shift points, line pressure, RPM vs TP, Shift Time, Shift RPMs, and Shift MPH. I ran the truck, changed the settings, ran the truck, changed the settings, etc... until it shifted firmly at the right times, but not harshly or too quickly. I basically set it up so that TQM was off, (except the last setting %), increased firmness of shifts slightly and hold gear a little longer.

It ran perfect on the way to and from work yesterday. Today on the way to work, it was banging through gears pretty bad and shifting early. Any ideas? Temp dropped by about 10 to 15 degrees today. I think its in the lower to mid 30s. Can the change in temp do it?

I babied it to work but I'm having my girlfriend bring the Predator to me at lunch so I can reset the parameters just to get home today. I don't want to kill the transmission.

[jcbst12]

Oh and I am aware that you guys have a fix for this. I have yet to try and link the damn thing to my PC without problems but I'll try again tonight. Any suggestions on how to deal with this in the meantime? Should I put the TQM back on? Will it need to be on for the "shift fix" you guys have?

[jcbst12]

Any help before I go home would be greatly appreciated!

[06MonteSS]

I have no idea man, sorry... I'd give the tech guys a call....

[jcbst12]

Ok, thanks anyways. The more I read on here the more it seems to be a common problem. Hard shifting with Silverados. I guess Im removing it until Mike can fix it for me. It was so weird, it was fine at first and now its all screwy.

[jcbst12]

Well I changed everything back to normal except the RPM vs TP. I kept the first two TQM options off. Line pressures I reduced to -2 on all gears, at partial and WOT. I'll try this out now. If it returns I'll be pissed cause I can't get the Predator to upload to my PC either. (AKA no fix from Mike)

[jcbst12]

Update: This is what I pulled off to make the truck ease into gears a little bit better, instead of banging through them. I turned off the TQM again (except for the last setting). I then reduced the line pressure at part and WOT as follows:
1-2 = -2%
2-3 = -2%
3-4 = -1%

I then turned the RPM vs TP and the Shift Timings back to stock. Now it upshifts close to the way it did stock. Is this safe? Im more concerned about the line pressures. I've increased them over stock before (in other vehicles too) but never reduced it. This won't hurt anything will it?

[jcbst12]

Yes / No? lol.

[06MonteSS]

I have no idea man, I don't have any tranny adjusting ability with mine... and Mike's gone till next monday... so hopefully someone will chime in for ya...

[jcbst12]

Thats cool, I always appreciate your help. Thanks! I was hoping another 99-02 Silverado owner would chime in. It seems to be working tho. It shifts pretty good without the TQM being on. It pulls the hell out of hills man, there is a ton of hilly areas around here and it was shifting like crazy before, now it holds until it drops below 1,000 rpm going up hill (which sometimes it will pull the hill anyways). I watched in Awe last night as I merged on our main highway here and it shot from 25 to 80 in a flash at half pedal. I know I'm ranting I'm just thrilled with the performance of this truck for the first time since I bought it. I can't wait until Spring when I can fine tune it a little better.

[neonhomer]

I have a 04 Silverado, 5.3L 4L60E. I turned off the first two TQM settings, and have my shift firmness set to around 15 for part throttle, and 17 for WOT. I also have shift time set at -10 for each..... Works good for me......

As long as your tranny isn't overlapping gears (two gears trying to engage at the same time), it shouldn't hurt it.... the quicker the tranny shifts, the better it is for it.

[jcbst12]

Well mine slammed through the gears until i backed the pressures off to about -2 and set the timing to stock. If I touch either of those two you can literally hear it shift, and too much adjustment will cause your head to hit the headrest followed by a sound thats similar to someone smacking the transmission with a hammer. I just hope the -2 pressures are ok. I think there are some programming and maybe mechanical differences between transmissions in 99-02 and the ones in 03-05. Thanks for your input!

How does Diablosport "fix" the hard shifting anyway? Is it something that can be done with the Predator. Until I get the PC Communications to work I'm SOL on "fixes".

[neonhomer]

I think it is done by setting the base setpoint to something difference.

[seltaeb]

There is a problem with some of the 99 - 02 GM trucks that when you upload any tune it will shift very hard after going wot. I had the same problem. Install the tune and the truck shifted great untill I went wot then it would just slam into gear and the only way to make it shift smooth again would be to turn off the truck for about 30 seconds and all was normal. I'm willing to bet that if you do a wot run that it will also shift very hard till you turn off the truck. The only way to fix this is to get a custom tune from Johan or Mikel. I did and it shifts perfect now.

[jcbst12]

Ok, thats what I figured. I wonder what they changed on it?