New Luder who just dicovered hondata; q's

H22_Speedracer · Post by **H22_Speedracer** » Sun Oct 13, 2002 5:28 pm

My buddy just got his rsx-s tuned by hondata and now his vtec ingages at like 4.1k and rev limits at 8.9k or something. i was wondering what system this was and if its available for the 97-01 prelude base model. lastely i was reading on the website and it talked about obd2-obd1 conversion is this a whole new ecu or just some conversion cables.

H22_Speedracer · Post by **H22_Speedracer** » Sun Oct 13, 2002 5:29 pm

Btw my motor is an h22a4, and i dont know what my ecu is

AndyE · Post by **AndyE** » Mon Oct 14, 2002 12:03 pm

The RSX Hondata modification is equivalent to "chipping", it adjusts the fuel/timing/cam phasing for more power. They simply write new data into the existing ECU, which is possible because the latest ECUs are field upgradeable (by someone with the proper tools, usually a Honda/Acura dealer).

Your Prelude uses an older style OBD-II ECU that contains a CPU with an integrated PROM that can only be written to once. It is possible to install a new chip with updated fuel/timing maps, but it takes a new chip each time you want to change the map, and as I recall the chips are $150-200 each.

A better alternative, and what Hondata recommends, is to convert your car from OBD-II to OBD-I. You remove your OBD-II ECU, set it on a shelf in your closet, and purchase an OBD-I ECU and an adapter that will let you plug said OBD-I ECU into your stock OBD-II wiring harness. Correctly modified, an OBD-I ECU will support the use of an external ROM chip to store a new ECU program and fuel/timing maps. This is how the s200 and stage2/3/4 systems work...they provide new ECU code and new fuel/timing maps for modified OBD-I ECUs.

-Andy