Sluggish Low End??

[Tweeter400]

I didnt notice it until today when I drove my fathers 99 with the 5.3, my truck is very sluggish on the low end? I checked the RPO codes and we have the same rearend. His truck will light'em up from a dead stop, mine will just chirp from the same spot on the road. I think it might have something to do with the tranny because my truck is sluggish on shifting. From rolling about 20, I put my foot in it and it accelarates about 3000 RPM than down shifts??

 

Any insight is appreciated!!

[Dihappy]

Hmm i wonder if torque management is more prevelent on the newer trucks than on the 99's???

 

My 99 with 315's will also light em up, although not for long

 

Yes ive got 4.56 gears but thats almost factory.

[Tweeter400]

Torque Managment??

What do you mean by that??

We both have the oem 265 Firestone Tires with 3.73 Rearend.

[Dihappy]

Torque management is something GM incorporated into the new trucks so as to avoid too much torque when you stomp on it.  

 

Its suppose to lessen impact on the drivetrain and thereby increase the life of the parts.

 

Maybe someone can give you a better definition.

[Tweeter400]

Is there a way to disable the torque managment??

Would getting a Hypertech Programmer help with the low end problem??

 

Thanks!!

[gandolphxx]

Here is a description from one of the GM manuals - source has gotten muddy so I apologize for not giving proper atribution.

 

With the GEN III VS engine, Torque Management is a function of the PCM that reduces engine power under certain conditions, included in which, is the transmission upshifts and downshifts.

 

Torque Management is performed for the following reasons:

 

1. To prevent overstress of the powertrain components.

2. To prevent damage to the vehicle during certain abusive maneuvers.

3. To reduce engine speed when the IAC is out of the normal operating range.

 

The PCM monitors the following sensors and engine parameters to calculate engine output torque;

- Air/Fuel ratio

- Mass Air Flow

- Manifold Absolute Pressure

- Intake Air Temperature

- Spark Advance

- Engine Speed

- Engine Coolant Temperature

- A/C Clutch Status

 

The PCM monitors the torque converter status, the transmission gear ratio, and the engine speed in order to determine if torque reduction is required. The PCM retards the spark as appropriate to reduce engine torque output if torque reduction is required. The PCM. also shuts off the fuel to certain injectors to reduce the engine power In the case of an abusive manoeuvres.

 

Instances when engine power reduction is likely to be experienced, are:

 

a. During transmission upshifts and downshifts.

b. Heavy acceleration from a stand start

c. The IAC is out of the normal operating range.

d. When the driver is performing stress-inducing (abusive) maneuvers such as shifting into gear at high throttle angles or shifting the transmission from reverse to drive to create, a rocking motion. The driver is unlikely to notice the torque management actions in the first two instances. The engine power output will be moderate at full throttle in the other two cases. The PCM calculates the amount of spark retard necessary to reduce the engine power by the desired amount. For example the PCM disables the fuel injectors for cylinders 1, 4, 6, and 7 in the case of an abusive maneuvers.

 

The only way to solve this problem is with a custom chip - none of the off the shelf programmers can change it to the best of my knowledge.