A little more insight into the SCT programmer. About five years ago I installed heads, injectors and a VEC2. The car ran good at wot, but, had several issues from idle through part throttle. This always bothered me, but, no matter how I tuned with the VEC i could not get rid of the problems.
Last year I weaned the car off of the wot settings and the timing. I also changed some of the inherent delays built into the PCM, after this the part throttle operation improved dramatically. I still was using the VEC for the injector offset. Personally, I believe this is the biggest problem with the VEC. It is too slow and it fights the closed loop operation, therefore, causing a jerky transition at certain rpm/map values.
This weekend I used the SCT package to control the offset for the 50 lb injectors. The VEC is not being used for anything at this time. The difference is huge, the part throttle operation is like a new stock car. All the part throttle issues are gone, it never was the performance modifications that caused the problems it was the VEC. My guess is that a lot of the problem was associated with the way the VEC controls the injector offset and the problem would not be as much of an issue if the VEC was not controlling this function.
This is not meant to condemn the VEC, there was no other simple fix prior to its inception. It has helped a lot of cars make some nice hp. At this time though the SCT package is way too easy and virtually controls all aspects of the PCM.
As a sidebar, Dan form Viper Specialties is a great resource if you have questions on the SCT system.
Last year I weaned the car off of the wot settings and the timing. I also changed some of the inherent delays built into the PCM, after this the part throttle operation improved dramatically. I still was using the VEC for the injector offset. Personally, I believe this is the biggest problem with the VEC. It is too slow and it fights the closed loop operation, therefore, causing a jerky transition at certain rpm/map values.
This weekend I used the SCT package to control the offset for the 50 lb injectors. The VEC is not being used for anything at this time. The difference is huge, the part throttle operation is like a new stock car. All the part throttle issues are gone, it never was the performance modifications that caused the problems it was the VEC. My guess is that a lot of the problem was associated with the way the VEC controls the injector offset and the problem would not be as much of an issue if the VEC was not controlling this function.
This is not meant to condemn the VEC, there was no other simple fix prior to its inception. It has helped a lot of cars make some nice hp. At this time though the SCT package is way too easy and virtually controls all aspects of the PCM.
As a sidebar, Dan form Viper Specialties is a great resource if you have questions on the SCT system.
