Celica Forums General Discussion Exterior PiggyBack

explain to me what a piggyback is and what it does and why its beneficial? And whats the difference between ecu and ecm? I want my computer reprogrammed but keep runnimg into dead ends on how it is impossible unless you have lots of money and bla bla bla.

piggyback:
i dont have a definition but it is like the s-afc you are piggybacking this to the ECU ... it is an addition to the existing computer.

electronic control module:
(ECM)
[1] The master computer responsible for interpreting electrical signals sent by engine sensors and for activating automated engine components and processes accordingly in order to produce optimum performance.
[2] A GM term and also a generic term referring to the computer. The ECM is the brain of the engine control system receiving information from various sensors in the engine compartment. The ECM calculates what is required for proper engine operation and controls the different actuators to achieve it Also called "electronic control unit"

electronic control unit:
(ECU)
[1] A microprocessor and memory with electronic maps, forming the central part of an engine management system or of subsystems such as a fuel injection or ignition system.
[2] The "brain" of an ABS system. The ECU reads impulses from the wheel speed sensors to determine if anti-lock braking needs to take place. If so, the ECU controls the cycling of the solenoid valves in the hydraulic control unit. Also called "Electronic Control Module"

so they are basically the same thing. How do we go about piggybacking our system? Would this be beneficial?

well that depends on what you are trying to accomplish and what kind of product your using. basicly any piggybacking is just going to interupt some type of signal and modify it so that the ECU thinks something else is happening than what the engine is actually doing.

Serious performance comes from completely replacing the ECU with a stand alone ECU system.I can't remember the name of the company that makes some right now

Apexi makes the most commonly used AFC for the celica (but I think it's only GTS).. either way, you should have a qualified shop intall it, and the benifit isn't worth it without Forced induction (you NEED something with forced induction, either a reprogrammed ECU or something to tell the injectors what to do, a turbo would FREAK out your ecu without it). There are 2 types, the first one feeds the ECU modified info based on a user tuned program, the second (and IMO safer)takes the data FROM the ECU and relays it to the engine with a modification from a program.

I think the second makes more sense and is safer, since the ECU is better equipped to read the info coming from the engine and the ECU just intercepts that info and sends modified info to the fuel injectors based on your requested air fuel mix for that RPM. These really take allot of know how to tune however, if you try to wing it you could blow up your engine or cause an engine fire (and as you probably know 1 engine fire is usually enough to total your car).

I looked into AFC for the GT a while back, there are a couple out there, but they need to be tuned by a qualified shop and I couldn't find one. I would like to know what my ECU is doing with my A/F mix though, just out of curiosity.

IMO the best way to manually reprogram your ECU is to drive it consistantly a certain way.. if you want better performance, drive it hard and the ECU will give you more fuel... that's what the "intelligence" that they advertise IS... it is programmed with simple AI that learns your habbits and adjust.

[ 04-29-2003, 10:43 PM: Message edited by: FX-MAN ]

Well, I've said it before and I'll say it again. I am saving my money for turbo.

yeah me too.. gonna hold off on it till the CARB exemption goes through, maybe even put it off till next summer so I can hear some reviews.. I am considering getting a new bike instead (looking at a sweet CBR, a friend at work wants to go riding all summer, the road between vancouver island and whistler mountain is like the winding cliff mountain roads RIGHT out of movies, and I havn't had a bike in 5 years soooo, maybe I'll just take the turbo money and cure my need for speed that way..).

Hell Yea! That sounds awesome Simon. I wish I had a motorbike.