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Scenerio 2 : OBD2 engine into an OBD1 vehicle
Author: Katman / Created: April. 05 / Last Updated: Jan. 08


This article explains MY WAY of how to get a JDM or US OBD2 B-series engine running in a OBD1 civic/delsol/integra vehicle by using an OBD1 ecu or JDM OBD2 ecu.

This type of swap is common nowadays and is highly asked about on many Honda message forums. One swap that instantly comes to mind is the JDM ITR engine or B18C-R into an EG civic or DC integra. Personally, I'm sick of posting up every little detail of how to do this swap on H-T, so I've finally created this article that I can directly link newbs to.

The information I'm providing is a quick run down of what you need in order to get an OBD2 engine up & running in your OBD1 vehicle -- REF/smog legalities aside. Getting your car REF'd (smog legal) is a whole other beast which I can make an article about at a later date.


All 92-95 Honda civic/delsol/and integra's are ALL OBD1 spec. Yes, that means 92-93 DA integra's are OBD1 for you that didn't know! What's neat about OBD1 vehicles is that you can swap around OBD1 electronics (distributor, injectors, ecu, starter, alternator, and most wire engine wire harnesses) between virtually any fellow OBD1 civic/integra model respective to B or D series engine of course.


Required parts in order to bolt an OBD2 B-series engine into EG/DC chassis:
('94-95 integra owners can reuse the items you already have that are mentioned below)
  • 94-01 integra or 99-00 Civic Si front tranny bracket (from any 5speed model)
  • 94-01 integra rear engine "L" shaped bracket (from any 5speed model)
  • 94-01 integra driver side 3-post mount (if going B18B/C/C5 - not needed if going B16/B17!)
    Note: You can reuse your existing civic/delsol driver side dual-post mount if going OBD2 B16A
  • 94-01 integra or 99-00 Civic Si A/C bracket
  • 94-01 integra or 99-00 Civic Si complete shift linkage
    Note: Delsol owners must use a B-series delsol shift linkage (rare to find used; best if bought brand new from Honda)
  • 94-01 integra or 99-00 Civic Si complete axles w/half-shaft
  • A U.S. 96-01 integra engine wire harness is a MUST for this type of swap!
    This is a key ingredient in getting an OBD2 engine to work in an OBD1 vehicle. The ever so clever Honda engineers were cool enough to make the US OBD2 Integra/Delsol engine wire harnesses backwards-compatible with OBD1 vehicles.
  • OBD1 ecu to power the OBD2 engine or an OBD1-> JDM OBD2a/b ecu jumper harness adaptor to adapt a JDM/US OBD2 ecu


Because of chassis differences, OBD1 DA integra owners will have to reuse their existing motor mounts, shift linkage, axles, and cable transmission on the OBD2 engine, which is all completely compatible. However, for wiring & ecu, they can use a 96-01 US integra engine wire harness and ecu information below.


Now, the reason for using a US OBD2 integra engine harness is to save you time & money in not having to convert the OBD2 engine to OBD1 spec! Do note that you cannot use a JDM OBD2 integra engine wire harness because it is designed for a right-hand drive vehicle! The main plugs are on the wrong side of the harness/engine bay. Save yourself a wiring migrane and get yourself a U.S. OBD2 integra harness!

If you were wondering about using a U.S. OBD2 civic engine wire harness - fuggedaboudit - you cannot use an OBD2 civic wire harness in an OBD1 vehicle because of it's 1-piece design (harness is one piece from the engine through the firewall, all the way to the ecu plugs). OBD1 civic/delsol/integra & OBD2 integra's all use a 2-piece design (harness breaks off at the shock towers) which makes it possible for backwards compatibility.

When it comes time to install the OBD2 integra wire harness, there will be a few plugs that will not plug into your OBD1 vehicles main shock tower plugs - don't worry! This is totally normal and everything will run just fine. Do note that if you are dropping an OBD2 VTEC engine into a non-VTEC OBD1 vehicle , you will have to wire in VTEC, the knock sensor, and IAB (GSR/SiR-G engines only). You will have to wire these items in the same fashion as if an OBD1 engine was in your vehicle - same ecu pinout locations.

Also, if you're dropping in a JDM OBD2 engine, these motors do not have a VTEC Pressure Switch (VTPS). So, you'll have to perform a small wiring fix for this or swap out the JDM VTEC Solenoid (VTS) with that of a U.S. VTS. The VTPS has a 2 wire plug (positive & ground), the VTS has 1 signal wire.

VTPS FIX: Take the power wire for the VTPS and splice it into the VTS wire, then take the VTPS ground wire and ground it to the actual body of the VTEC Solenoid - that's it! If done correctly, your ecu will not throw a check engine light for code 22 (VTPS). If you wind up using a JDM OBD2 ecu, you do not need to perform this VTPS fix, because the JDM OBD2 ecu doesn't look for a VTPS.

I bet you're wondering about the ECU side of the swap now, eh? Well, it's simple - you have 2 options:
    1. (Best option)
      Simply use an OBD1 ecu respective to your engine type i.e. OBD2 GSR engine -> use an OBD1 GSR/P72 ecu. This will plug directly into your existing OBD1 factory ecu plugs and power the engine. If there's no equivilent ecu available for your engine type (i.e. OBD1 ITR ecu - no such thing) use a reprogrammed OBD1 ecu like a reprogrammed P28.

    2. (Good option if you have the $$)
      If using an OBD1 ecu isn't your style and you'd rather use an OBD2 ecu, not a problem, it's doable.
      First, you'll need to purchase an OBD1>OBD2a/OBD2b jumper harness adaptor - (which I sell) depending on which OBD2 type (a or b) you planning to go with.
      Second, you'll need to figure out if you want to use a JDM or U.S. OBD2 ecu. If you decide on a U.S. OBD2 ecu, then you will need to manually wire in a 2nd 02 sensor and perform the "CKF Fix".

      JDM OBD2 ecu users do not have to worry about a 2nd 02 or the CKF sensor as these ecu's are not programmed to look these sensors.

      You can read about the CKF Fix -> HERE
      At this time I do not have a 2nd 02 wiring article ready.


The information in this article applies to:

  • OBD1 civic/delsol/integra vehicles