K-series JDM PRC / PRD / PRB ECU info

Upon researching Type-S swap info on RSX base & EP3 Civic Si vehicles, the optional use of JDM K-series ecu’s comes up often. Specifically, the JDM DC5 Type-R “PRC” or JDM EP3 Civic-R “PRD” ecu’s. These two ecus are ultra handy for use in legacy chassis (88-00 civic/90-01 integra) K-swaps, being it lacks an immobilizer which all US K-series ecu’s have. This saves money for the K-swap end-user (temporarily) in not having to KPRO the ecu right off the bat in order to get the vehicle running and driven around.

For 02-04 RSX & 02-05 EP3 Civic Si’s, some are inclined to use the JDM PRC/PRD ecu for whatever reason and typically experience the no-fuel-pump-priming issue, which is an easy fix. Simply swapping pin E1 down to E10 fixes this issue. I had to do the same in my K-swapped EG when I would switch between my KPRO’d PRD ecu and AEM 1030 EMS (RSX-S ECU).

Here are some known differences in the factory programming for PRC/PRD vs. PRB ecu’s:

• FUEL PUMP RELAY
  PRC/PRD fpr is located at ecu connector E10
  PRB fpr is located at ecu connector E1
• IMMOBILIZER SYSTEM
  PRC/PRD disabled/non-existent
  PRB enabled
• VTC MAPS
  PRC/PRD is programmed for K20A Type-R camshafts
  PRB is programmed for K20A2 camshafts / 05-06 PRB is programmed for K20Z1 camshafts (similar to Type-R cams in many ways)
• FUEL & TIMING MAPS
  PRC/PRD are programmed for premium higher octane rated fuel (higher than 93)
  PRB programmed for US rated octane fuel (91-93)
• FUEL INJECTORS
  All three ecu’s are programmed for 310cc injectors
• OXYGEN SENSORS
  All three ecu’s share the same dual 02 sensor configuration ie. wideband primary 02 and narrowband secondary 02
• VSS (VEHICLE SPEED SENSOR)
  *PRC/PRD programmed for low frequency VSS (mechanical style mounted on rear of trans)
  PRB (02-04) same as PRC/PRD .
  PRB (05-06) programmed for high frequency VSS (located on front side of trans)
  *I don’t believe Honda of Japan ever released a high frequency version VSS specifically for the DC5/EP3 Type-R’s unlike the US 05-06 RSX. Honda did introduce the high frequency style VSS’s on the 06-10 FD2 CTR though, which used a whole different style ecu altogether (drive by wire, etc).
• SPEED LIMITER
  PRC/PRD set somewhere between 110-120mph
  PRB no speed limiter
• VTEC PRESSURE SWITCH SENSOR
  PRC/PRD disabled
  PRB enabled
• 6-SPEED ECU
  All three ecu’s are programmed for K transmissions with a 6-speed gear selector

There may be other slight differences I have yet to discover (ie. multiplexor) and will update if I come across these things.

Now, seeing the list of differences, here are some caveats of using a PRC/PRC ecu in an 02-04 RSX Type-S or K20A2 swapped 02-04 Base RSX & EP3 Civic Si:

• Fuel pump relay – fuel pump pin out E1 needs to be swapped to E10 or no fuel pump activation will occur
• No immobilizer – no need to reprogram your RSX/Civic Si key!
• VTC maps are programmed for K20A Type-R cams NOT K20A2 cams – performance will lack because of this – engine will run regardless but not at its optimum VTC (unless you swap in K20R or K20Z1 camshafts)
• Fuel & timing maps are programmed for Japanese higher octane pump gas – performance will lack because of this
• Speed limiter – can’t do anything about this!
• 02 sensor(s) – make sure to use a Type-S primary (wideband) and secondary 02 sensor(s). RSX base and EP3 Civic Si primary 02 sensor is not compatible with PRC/PRD programming (may throw cel or just run like crap)
• VTEC pressure switch – will not be a problem even though K20A2’s are equipped with this sensor