Hi guys... expecially those BLT who like to bully SVT :D
Watch out one day you might experience sluggish on your belove BLT engin, and will be out-run by even a SVT A/T... hehehe...
Here are some brief of the problem...
Each time when the VVT solenoid is triggerred, the Transistor has to suferred for a surge current (which appears in milli-sec only). This surge current will create heat on the Transistor body and need to be dissipate properly. For SVT engine, VVT only trigger when RPM is beyond 4400rpm. Since we are not often running the engine up and down around this RPM level, the Transistor is able to dissipate the heat before the next trigger is coming.
But for BLT engine, the VVT is design to be trigger by TPS angle and RPM, which is more frequent than SVT. The average heat created on the BLT Transistor is much higher than SVT, and is beyond the specification of the Transistor. So it will die, after you pushing your engine too hard.
Here is some photos for your viewing pleasure...