So i just got done tearing apart my engine, and decided i might as well remove the PCM from the car before i go in for the night and i stumbled upon this plugged inbetween the harness and the PCM. The previous owner must have put it on. Will this effect a mail order tune as long as i dont re-install it?

 

no and throw it in the trash.

 

Those things only offered a slight increase in performance over the factory tune.

Chuck it in the trash and you will be 100% happier with a custom tune.

 

Frame it