Honda / Acura K20a K24a Engine Forum banner
1 - 5 of 5 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter · #1 · (Edited)
I'm typing this out to document all of the things that I've had to do to my 05 EP3 to make a 06 RSX Type S powertrain completely compatible with my EP3, including making it PA safety and emission compliant (which is very difficult to do in my county). I'm also a tech working at a Honda dealership, so I had all the troubleshooting resources that I could possibly need to figure out how to make my vehicle work properly.

I started off with a 05 EP3 that had the HFP package installed on it. I bought it from Virginia, and it lived most of its life in Texas, so it had little rust which was great. I originally also owned a 06 RSX Type S, which is where my swap came from after I rolled my RSX.

I was going to pull off the powertrain swap after an eventual totalling accident involving my RSX (wasn't trying to pull off an insurance scam, I'm just prone to accidents that by happenstance totals a car, so I wasn't surprised when I wreaked my RSX). After my accident, I assessed that my engine and trans survived the roll over, and the only thing that broke on the engine was the evap canister purge solenoid.

On to what I used to make the swap work, I was using the ECU, the engine, the trans, the A/F sensor from my RSX. Taking the A/F sensor was actually imperative for the car's emission operation, but I didn't realize that at the time. Me taking the A/F sensor off my RSX was due to a completely different reason. For the wiring, I used my EP3's engine harness, and to convert the ECU and the VSS to be compatible with the EP3 harness, I used a ECU jumper harness from HAMotorsprts, and a basic VSS jumper harness. To convert the VSS signal to the chassis side of my car, I used the K-Tuned all in one VSS converter. I also used my old K20A3 knock sensor due to me using my EP3's starter and charging harness.


Now down to what I did to make everything work. To answer the question everyone probably knows, the 05-06 RSX Type S powertrain will directly bolt into an EP3, and it uses the same mounts (although I had to replace a few mounts myself due to half of them breaking on me prior to the swap). I ended up with two no signal engine codes, and one FTP sensor code after replacing the broken EVAP canister purge solenoid, which I'll cover with my fixes.

First, I had to make the VSS work properly for both the ECU and the chassis side. According to the instructions, it give two ways to wire the converter into place, but I've modified the 02-04 K20a2 wiring instructions. It told me to take the input signal wire and wire it to the single VSS wire going to the engine compartment and wire the output to the ecu and chassis wires. Doing that makes the chassis see the correct signal, but makes the ECU not read the correct signal, basically running the engine in restricted/neutral mode and giving a P0720 code. Basically to work around that issue, instead of wiring the input to only the engine wire and output to the ECU and chassis wire, wire the input wire to the engine and ECU wires, and wire the output to the chassis wire, therefore allowing the ECU see the vehicle speed, while the chassis sees the converted signal speed. The only thing that seems to be a downside to how I wired this is that the speedo needle at start will move up and then back down on start up, possibly due to the signal voltage, so I consider that normal operation.

Down to the no signal codes and the work around. I had a no signal code for the knock sensor and the A/F sensor. If you aren't using the starting sub-harness from a 05-06 RSX Type S, you can take out the original K20Z1 knock sensor and replace it with a known good K20A3 knock sensor (which I did), as a K20A3 sensor will screw into the space where the knock sensor will go, and the ECU is just looking for any knock sensor signal, and will clear that no signal code.

For the A/F no signal code, this is vehicle specific. The 05-06 RSX Type S ECU is looking for the A/F sensor signal from a 05-06 RSX Type S. I originally didn't take the A/F sensor from my RSX for this reason, but I figured it would be handy to have just in case an engine code comes up for it, which it did. Again luckily the A/F sensor from the RSX will fit into the EP3's cat, and that took care of that no signal code.

On to the FTP code, which was P1454 FTP sensor performance. This is due to the 05-06 RSX Type S having the newer current EVAP system design, and the ECU doesn't have power logic for the bypass 2 way valve. To clear this all you have to do is either delete the bypass 2 way valve completely and use a Y/T vacuum joint to join the fuel tank pressure, the FTP sensor, and the EVAP canister shut valve together, or wire the valve to the ignition. I opted for the former because I was sick of wiring shit. It will pass the Honda evap function test and the EVAP system will then perform normally, and clear the P1454 code.

Now my EP3 is basically a CTR minus some chassic and braking components, but it's close enough for me, and I hope this will help anyone trying to perform the same exact swap into a EP3 or a base manual RSX.
 

·
Premium Member
Joined
·
908 Posts
EP3's do not get the credit they deserve. They are a great platform like the DC5 and both of them handle very well for road course racing. When I had my EP3 I started adding chassis bracing one brace at a time, and I could tell a difference in the chassis and acceleration after each one. I think the upper front strut bar and the 4pt. harness bar gave me the best effect change. The C-pillar and the upper rear strut bar had decent improvements, not a much as the UFSB and the harness bar, still the differences could be felt.

Looking forward to seeing some pictures of your car.
 

·
Registered
Joined
·
362 Posts
Pics would be great. Not being a Honda-guy, I have no idea of the different Chassis designations, only the basic model names. :p

I can ID with having to do state emission work-arounds - didn't have to with my K-swap, however I have with other cars I've modded.
 
1 - 5 of 5 Posts
Top