PCM Code

[X JBM X]

I'm not quite sure what that means...

In other words, am I going to toast my tranny using this chip, or should I be good to go? I mean, I LOVE the extra power that I'm getting, and the shifts feel great when I'm on the throttle, but when cruising around town at ~35mph when the TCC kicks in, and it does that jerking thing, I don't wanna burn up the trans.

Since I didn't go back to read if I already posted it, I'll try to describe the feeling.

It's like if you're in a manual trans car, and you go to switch gears, push in the clutch, shift, and then hit the gas a little bit before releasing the clutch (almost like you let the clutch out a little too fast when not racing and just dumping it) making the car forward buck a little before slowing down the RPM's to properly engage the gear.

[cj45lc]

That is kinda funny because mine kinda (not kinda it does) BUCK for lack of a better way to describe it. Just does it on the 65t under light throttle at the same shift. If I put my foot in it the shifts are great but in town it feels like something is gonna tear up. I've been using the 80dd with the horse trl & temps stay good, so I'm hoping it is something that could be adjusted when I see ya'll at Bandimere in Aug.

[cleatus12r]

OK, I get it now.

You're not going to hurt a thing. It may be a bit awkward feeling, but it is ONLY the torque converter clutch applying at a fater rate than stock.

The longer it takes the shift (or torque converter clutch to apply), the more "burn time" there is, and the more damage it does. The factory designed these SD trucks to shift "transparently" so that you can't feel the shifts. Unfortunately, it also takes a toll on the friction elements inside the transmission by causing a lot of heat during the shift.

By shortening the time it takes the shift to occur, the heat produced by the friction elements is kept to a minimum. The only drawback is the firmness of the shift. It is fixable.....but at the expense of drawn-out shifts; which for a higher-hp shifts can burn up frictions in very little time.

[X JBM X]

been reading a little bit about this PCM code.

Apparently the PMT1 is supposed to be the "best"

Since mine is NVK2 - it specifies "49S/AUTO/COLD"

what would the difference between the 2 be?

What does that 49s/auto/cold mean?

[cleatus12r]

Well, A LOT of people think it's the "best". I personally love it, but my ex-wife hates it. She really liked the NVK4 strategy better because of the lack of TCC apply soon after the 2-3 shift. Most driving styles will cause the NVK2/4 PCMs to apply the torque converter clutch after the 3-4 upshift at 38-42 MPH.

Some don't like it. It's kind of the nature of the beast, but since most all people who are able to run PMT1 really like the way it works over their current strategy, that's the one we normally use.

[X JBM X]

EDIT: didn't see teh second post.

[cleatus12r]

Originally Posted by X JBM X

been reading a little bit about this PCM code.

Apparently the PMT1 is supposed to be the "best"

Since mine is NVK2 - it specifies "49S/AUTO/COLD"

what would the difference between the 2 be?

What does that 49s/auto/cold mean?

49-state (non California)
Automatic transmission
Increased start of injection when cold for smoke control.