Can anyone solve my problem? SC400

[jibby]

Here is the deal, I have a 92 sc400 modified I am running nos, with an apex piggy back system, intake is redone, and exhaust. Engine is stock. What has happen is the car was running smoothe and fast had 2 1/2 exhaust piping throughout with high flow mufflers. My low end torque was rediculous with the dragon torque converter and diff gearing lsd. What I did is change out my stock cat to a magnaflow cat to get a little more top end and immediately when I changed it I developed a lag or hesitation in excelleration at full throttle exactly between 1000-2000rpm only. With nos engaged I do not notice because tires are spinning out. However I took it in to Tm Engineering to be re-dyno'd and tuned and thinking the exhaust cat change screwed up my piggy back ecu tuning or something along those lines. Todd at Tm worked with it and could not tune and fix, I then changed out the mass air flow sensor and throttle body sensor, oxygen sensors. I even put back the origainal cat and the problem still persists. I then changed back to the magnaflow cat and that did not correct the problem of course, I cleaned out the trottle body with carb cleaner nothing. Can anyone help me on this I am going nuts it only happens at full throttle at 80% it's ok. Please advise, I am open to any suggestions. Also sometimes when it's cold it runs better. I just can't figure this one out, I am about to change to a stand alone ECU to solve the problem. Anyone. The problem seems to be getting better with time if that sounds crazy, but not to much better. HELP!!!!!!!:wtf:

 

[SC & RX]

Could it be the new cat burned off some stuff that is fouling your O2 sensors?

 

[SCV8]

Try doing an ecu re-set by removing the main fuse to the computer, or just remove the battery terminal if you're not patient.
Extra timing advance will help things run better; maybe it's time to step up to a piggyback that will control that also, like Unichip, or SplitSecond.

 

[jibby]

Thanks it is definetely a foul up with the ECU I determined that. Todd had it running lean for the nos application. I need a new ECU piggyback. Which is the best and most reliable one out there? Is it the greddy-E-manage, Unichip or SplitSecond? I am also reading that the piggyback ECU's are not very reliable and get out of tune fast because the stock ecu learns and changes things up over time. Is that true?