Ok, I'm currently building my b18c up for boost up to around 10 psi daily driver and maybe 12-13 strip. But what I wanna know is when do you know you Hondata? I done a little research on them but can you tune the engine without it. Like maybe get a piggyback and do it that way? And what are the differences between Hondata and a piggyback other then price.

 

The ECU has maps for fuel and timing. The way they work is that there's a table with MAP sensor voltages (corresponding to a certain amount of airflow) and RPM. At each point on the table there is a fuel value which is then sent to the injectors by way of a "duty cycle" signal. The computer constantly ajdusts how much fuel is being injected based on this map.

The main advantage of a Hondata or similar solution is that it lets the ECU understand what boost is. From the factory the table does not extend to MAP sensor voltages that correspond to higher-than-atmospheric (i.e. boost) manifold pressures. If you get a MAP voltage that's outside the table, the computer goes into limp mode. You can cure this by bleeding boost away from the MAP sensor with a valve, but then your ECU is pulling the fuel data from a different point on the table. If you upgrade the ECU to a programmable one like AEM, Hondata or ZDyne then you get a new fuel table which has values for MAP readings which indicate boost.

A piggyback computer does nothing to the actual fuel table inside the motor. Generally they change the voltage being sent to the MAP sensor input of the ECU. You want more fuel, it sends a higher voltage to the ECU and voila, the ECU thinks that more air is going into the motor than there actually is. Similarly, if you want less fuel then you can dial back the voltage and the ECU thinks less air is going into the motor.

The practical offshoot for this is that you can run lager injectors (DSM 450cc/min for example) and dial back the fuel on the piggyback, and have the car run essentially fine. Since what in essence you're doing is preventing the ECU from seeing boost, you don't need a bleeder valve and you don't get a check-engine light. The higher flow-rate injectors get sent the same signal as the stock ones but put more fuel into the motor. A piggyback is cheaper and simpler than having the ECU reprogrammed, so basically you have to decide if you want something that will run "fine" or if you want to get the most reliability and power possible for a few hundred bucks more.

 

Thank you, I should of asked alot earlier then trying to figure that out myself. Thanks things are much clearer now. :thumbup:

 

Keep in mind that if an AFC is your piggyback of choice, and you opt to run DSM 450s, you can boost a maximum of 10-12lbs(at 40% fuel trim)before getting a MAP sensor code. If you plan on boosting more than that, I would just go Hondata now, and save yourself the trouble later on.