This is a Hondata-modified 2002-2004 RSX ECU and an adapter harness for the 05-06' RSX.
Hondata makes hardware modifications to the 2002-2004 ECU to enable it to work with the different sensors and actuators found on the 2005-2006 RSX ECU. After these modifications, the ECU will not function correctly on a 2002-2004 RSX.
Hondata only sells adapter harness with the modified ECU. An unmodified 02-04' ECU with adapter harness (with or without K-Pro) will not work on a 05-06' RSX without the internal ECU modifications performed by Hondata.
The 05-06' K-Pro is only certified to work in an 05/06' RSX. Engine swaps using an 05-06' RSX engine and gearbox into another chassis are not supported with the 05/06' K-Pro and adapter harness. The correct method is here: http://www.hondata.com/techk20transmissions.html
- An primary oxygen sensor from the 02-04 RSX or 02-05 Civic Si must be used. The 05-06 RSX O2 sensor will not work.
- OBD2 must be disabled to eliminate errors generated by the ECU looking for emissions items that the 05-06 RSX does not have.
- The speed sensor spins about 100 times faster on the 05/06 RSX gearbox as compared to the 02-04 RSX. Above 65-70 MPH cruise control may not function smoothly and may cancel from time to time. Also see Tech - K20 Transmissions
Which Donor ECU can I use?
Only the following ECUs can be used.
- 2002-2004 RSX Type S (PRB A03-A08, PRB-305 ECU). Should be used for a Type S
- 2002-2004 RSX (Base 5 speed) (PND -A0# ECU) Should be used for a Base
The stock 2005-2006 ECU part number PRB-A13 through PRB-A16 has a different microprocessor and cannot have a K-Pro installed.
These are the only harnesses that are guaranteed to work with the 05/06 K-Pro. These adapter harnesses are sold only with an 05-06 RSX-K-Pro.
- Blue Wire
- Sticker stating 05/06 Adapter (some adapters may not have stickers)
- Three white plugs or
- Two white plugs and a grey plug (from about June 2007)
If you are are having problems you may have a counterfeit adapter harness. To verify if you have a genuine adapter harness, contact Hondata with the serial number of your K-Pro.
Tuning the 05-06 RSX
The 05 ECU was replaced with a jumper harness and 04 ECU with K-Pro and then tuned. In the example below the 05 RSX was equipped with a cold air intake. The only change was from stock ECU (yellow line) to K-Pro + tuning (blue line).
Points of interest
- VTEC was set at 4600 rpm
- 18 ft pounds torque gain at 2000 rpm
- 15 ft pounds gain at 5800 rpm and at 8000 rpm
- 16 hp peak gain, but 20 hp gain at 5800 and 8000 rpm
This engine responds better to tuning than the K20A2, probably due to the better cams and the fact that the stock ECU runs so rich at the top end. A race header, with tuning will provide a significant increase in the mid range and top end torque.
We have cross referenced the 05 RSX intake and exhaust camshaft part numbers with those available for Japanese ITR.
The Japanese part numbers for the ITR intake cams are:
This is because there have been three revisions of the engine.
The US part numbers for the 05 cams are:
- 14110-PRC-030 (intake)
- 14120-PRC-030 (exhaust)
It is therefore our assumption that the cams in the 05 RSX are the Japanese ITR cams. which have the same lift but more duration than the PRB cams
(The 02-04 intake cam part number is: 14110-PRB-020 )