The terms piggy-back, and standalone are from times past. Back in the day....like 2006, LOL...there were several cars where physical removal of the facotory was required, and then you replaced it with something like an AEM "standalone". This is how we do it with the Evo and Supra, for instance. However with today's CAN networked vehicles, physical removal of the ECU is not necessary, and actually not desired at all. The stock remains to control the windows, gauges, ABS, and body controls. But the "standalone" ECU, such as Fcon, Haltech..etc.etc..takes 100% control over the engine.

Haltech, FCON, ProEFI all have 100% control over the engine, without any interference from the stock ECU.

 

+1 when we say piggyback it means it still rely on ECU to partially control the motor or offset/trick the ECU to get the final result. Example of Piggybacks are Unichip, SS, Emanage, Fcon IS..etc, because they still rely on the ECU. Haltech, ProEfi, Vpro are considered full standalone because they act as a standalone on controlling the Engine. Some people still uses the term Piggyback or Standalone literally but with the newer cars it doesn't apply just like what Sharif said.

This is why Utec are considered parallel EMS coz on boost they act like a Standalone but without boost they let the ECU take control..

 

well I have proEFI 48 box and the stock computer is still doing most of the work. ProEFI actually doesn't do hardly anything (except fuel richening) until above 15psi of boost.


stock computer still controls variable cams, I still have full use of OBD2 port etc.

Back on topic though....sorry don't know about emanage units except the blue sucks.

 

/\ trust me your ProEFI does have full control of your Fuel and timing above 0psi maybe even vacuum. Reason is the ECU get maxed out above 3psi so there is no way in hell that your ProEFI dont do anything under 15psi. If you are letting the ECU run the ignition/timing then your car would've already blown already. Like Sharif said we dont use the term Standalone literally anymore.

 

Youll be fine with the EU...ive been running it for 3 yrs and have never had a problem. Im running a Procharger making well over 400rwhp