J-man

If I punch it from a dead stop without doing a brake stand or anything, there is a very noticeable delay before the truck starts to move. Is this because of the tranny, or do I just need to stack an mp-8 or somehting to take care of this?

omaharam

The 315s don't help, but it's normal. Without the aid of the turbo, the throttle response of these trucks is pretty weak. A little left foot braking will take care of your problem.

metal_miner

Rolling into the throttle always gives me better response than matting it from a dead stop. To me, if I mat it, it seems like the "the fire is getting put out" and all that happens is black smoke.

J-man

So, even if I upgrade the tc , vb, and get an mp-8, that won't change?

jgiachino

I don't have an mp-8, but with the smarty level 9 and built trans, it still does it.....you dont need to do a full brake stand, just light brake at launch to build boost (couple of psi) and she's off to the races....

omaharam

TC will likely make it worse do to the tightness and lack of initial revving. The mp-8 will help for sure. I ran a Quad xzt pressure only for a while and it had more bottom end than the mp-8, but less overall power.

JCLeary

In my opinion it is the torque management built into the Cummins software you're feeling. It protects the transmission. On my '07 it seems to protect more when you mat the pedal versus rolling into it.

The best way to get rid of it is with a programmer. My favorite (and most responsive) was the Smarty.

jgiachino

Even on Smarty Wild 9, i get a lag off the line unless i brake it....it definately helps, but will not eliminate the lag when you mat it....makes a ton of smoke!

no_6_oh_no

Thats correct. In order to limit smoke most programmers do not start enhanced fueling until they are reading 12 psi of boost like the ECU.

DodgeCTD

I know exactly what your talkin about. I have ran the tst on 5/5 by itself and had the lag coming off the line at 20psi boost in 4x4 launch, and still have it with the smarty on 9 wild, I believe its the transmission, stock transmission just dont get it to the ground its sloppy. I think it might be cause of a loose torque converter. With the smarty on 9 my truck only made 390/775, stock trans just dont hold it well.

jgiachino

Agree the stock trans doesnt help...but i have a built trans and it still does it....definately puts the power down, but the tight converter slows the initial spool and therefore doesnt eliminate the lag....neither does wild 9 (althought it helps)

SMOKIN-U

mine does it as well but with no torque management and throttle sensativity its pretty darn peppy from a dead stop

tristan21

I dont mind it to bad and I run a A5K.

These things are GOING to have some lag. Its a turbo diesel. They are miles ahead of the first gens but itll never be erased.

Its in the genetics of the design. The action is not instantanious unless you have some boost. Twins are the same if not worse.

The only way to reduce it is to add lots of fuel, via cp3, inj, and mostly programming. Well that or add a cam.

jgiachino

Yeah, mine's peppy as well with moderate throttle (no lag at all)....what we're (at least me) talking about is from a stop, let off the brake and floor it all the way...and there's a 1+ second lag, 10' cloud of smoke and off to the races....

Snapoff

Well said.

A diesel needs fuel and the air to burn it....Lots of fuel with no air = No power. From a dead stop with zero boost I can almost put the fire out.

I am going to larger (much larger) injectors and turbos...so this phenomenon will become worse for me.
I am both having the torque converter set up looser and adding a cam to help combat this.

Nitrous oxide solves all lag problems, but gets pretty interesting on the street!