Civic-EG.com Forum 3.3.1

- Wed Feb 25, 2015 6:13 pm #352250 I should probably post this in the Chassis/Electirical forum but looks like no one reads the post there anymore.

I just bought a JDM B18C-SIR-G and its set up for RHD. I drive a Hatch and looks like I'll need to convert from OBD2 to OBD1. My question is, what all do I need to get to OBD1? I know I'll need a GSR obd1 dizzy.. Will I need a new engine harness that's set up for OBD1? Not sure if the harness needs to be set up for vtec? Will I also need a OBD1 ECU?

If I do need what I just listed, how much can I sell my OBD2 dizzy? And since the wire harness is set up for RHD, I'm assuming I can't really sell that.. And what about the ECU I have right now? How much can I sell the P72 for if I wont be needing it?

I need as much advice I can get on everything I could do. I was told I could buy a jumper cable too but I don't know crap about this kinda stuff

- Wed Feb 25, 2015 7:35 pm #352253 There is more than one correct way to install this swap. The reason I recommend this way is most people start with a single cam in their car. You will have an ECU and wire harness already which means no hunting down expensive parts like distributors. These adaptors, I have provided links to, make everything plug and play so you dont have to cut and splice wires. If you are comfortabe cutting, soldering, and heatshrinking you can do all of this without purchasing adaptors. If you have a non-VTEC ecu to start with (ie:PO6) most tuners/chippers have the parts available to convert it to a VTEC ECU look into phearable.net and xenocron.com for their services both are great to deal with.

You will need one of these adaptor harnesses to let you use the OBD2 dizzy on an OBD1 engine harness. Just match up which distributor you have (8 or 10 pin OBD2) and this will make it plug an play.
http://www.rywire.com/distributor-adapters-s/1823.htm

While it is possible to run an adaptor harness to use that ECU in your vehicle (found here http://www.rywire.com/ecu-jumpers-s/1824.htm) it is easier to sell that ECU on eBay and use an OBD1 ECU (you wont have to add a second O2 sensor). You will be able to use any chipped VTEC ECU or stock OBD1 P72 (NOTE: if you use a stock OBD1 P72 you will have to add wiring for the knock sensor to avoid a MIL)

For the engine harness just use an OBD1 single cam EG harness. You will have to use these adapors for the injectors or cut and splice the OBD2 connectors on yourself to save some money (http://www.rywire.com/product-p/inj-adapter-1-2.htm) If the harness you have is non-VTEC grab one of these subharnesses to wire in VTEC. (http://www.rywire.com/product-p/sub-generic-vtecsubharness.htm)

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[suspendedHatch]

- Thu Feb 26, 2015 8:26 pm #352283 That's one way, but then you have to buy all the adapters and pay $200-300 for an OBD1 USDM P72, and you'll spend some time trying to find one.

A better way to go is to get an OBD2 USDM Integra engine harness. 96+ Integras are now common to find in Pick Your Part type junkyards. It CAN'T be an OBD2 Civic harness, because those are one piece. The Integra harnesses are two piece meaning that they have the plugs on the strut towers like OBD1 harnesses instead of having one driver's side plug and a green plug near the ECU like the "one-piece" OBD2 Civic harness. You can't use a JDM harness because it's RHD, and it will most likely to be cut and damaged anyway.

Since you are using an OBD2 harness, you DO NOT need to make any alterations to the alternator, injectors, or distributor. It's all plug n play. The old way of swapping on OBD1 parts or splicing to OBD2 harnesses is pure insanity. Buying all the adapters trades insanity for expense and added bulkiness of wiring.

THE OBD2 USDM INTEGRA HARNESS PLUGS INTO YOUR OBD1 CIVIC HARNESS AT THE STRUT TOWERS. There's one plug leftover on the OBD2 harness that you don't need. Just zip tie it out of the way.

At this point you have several options:
1: Get an OBD1 USDM manual P72 and plug it into your Civic ECU harness, add pins to your ECU harness for knock, IABs, and VTEC and run the wires to the engine. This way has long been preferred, however, OBD1 manual P72's are now hard to find and tend to be expensive.

2: Almost the same as option 1 but get an OBD1 automatic P72 and convert it to manual. Not hard to do and the auto ECU's are much cheaper.

3: Get a P06 or P28, chip it, flash it with a B18C1 tune, alter the circuit board to add IABs and VTEC (P28 already has VTEC). Pay someone to do this for you. The major advantage is that you can then get the car dyno tuned. Options 1 and 2 can have the ECU chipped and tuned as well, but if you are going to do that you should save the money and headache and just do option 3.

4: Use an OBD2 manual P72 with an OBD1 to OBD2 conversion harness. OBD2 P72s are cheap and relatively easy to find. The conversion harness is less common than the others but readily available from Rywire for $140. You'll have to bypass the CKF and add wiring for knock, but this is a simple procedure. You'll also have to have a secondary O2 bung added behind the cat converter.

5: Use a JDM OBD2 P72 with an OBD1 to JDM OBD2 conversion harness. Probably the cheapest and easiest option but most likely will not pass BAR in CA. Options 1, 2 and 4 should pass BAR, with 4 being the most legit and legal option.


I'm doing option #3 also since I scored a free chipped P28 when I swapped an HX engine into a CRX for a friend. My other friend is a professional tuner who is getting the ECU flashed for me and adding the circuitry for IABs. When I move to CA I'll put the OBD2 GSR ECU in and get the car BAR'd (#4). The swap is coming out of my 97 GSR so I already have the ECU, just need to get the conversion harness.

I think I will do a pictorial since Civic-EG doesn't really have one. I just need to finish swapping my VX engine into my CRX before the VX can get the GSR engine.

- Tue Mar 03, 2015 7:46 pm #352360

There is more than one correct way to install this swap. The reason I recommend this way is most people start with a single cam in their car. You will have an ECU and wire harness already which means no hunting down expensive parts like distributors. These adaptors, I have provided links to, make everything plug and play so you dont have to cut and splice wires. If you are comfortabe cutting, soldering, and heatshrinking you can do all of this without purchasing adaptors. If you have a non-VTEC ecu to start with (ie:PO6) most tuners/chippers have the parts available to convert it to a VTEC ECU look into phearable.net and xenocron.com for their services both are great to deal with.

You will need one of these adaptor harnesses to let you use the OBD2 dizzy on an OBD1 engine harness. Just match up which distributor you have (8 or 10 pin OBD2) and this will make it plug an play.
http://www.rywire.com/distributor-adapters-s/1823.htm

While it is possible to run an adaptor harness to use that ECU in your vehicle (found here http://www.rywire.com/ecu-jumpers-s/1824.htm) it is easier to sell that ECU on eBay and use an OBD1 ECU (you wont have to add a second O2 sensor). You will be able to use any chipped VTEC ECU or stock OBD1 P72 (NOTE: if you use a stock OBD1 P72 you will have to add wiring for the knock sensor to avoid a MIL)

For the engine harness just use an OBD1 single cam EG harness. You will have to use these adapors for the injectors or cut and splice the OBD2 connectors on yourself to save some money (http://www.rywire.com/product-p/inj-adapter-1-2.htm) If the harness you have is non-VTEC grab one of these subharnesses to wire in VTEC. (http://www.rywire.com/product-p/sub-generic-vtecsubharness.htm)

I forgot to mention that I have a B18a1 LS engine in there right now. So you recommend I get a jumper harness to just make my current set up plug and play? Of course I can just use my old Harness if I wanted to.

As far as the ECU goes... You're also saying I can just chip my obd1 ECU to set it up for vtec?

- Tue Mar 03, 2015 7:59 pm #352361

That's one way, but then you have to buy all the adapters and pay $200-300 for an OBD1 USDM P72, and you'll spend some time trying to find one.

A better way to go is to get an OBD2 USDM Integra engine harness. 96+ Integras are now common to find in Pick Your Part type junkyards. It CAN'T be an OBD2 Civic harness, because those are one piece. The Integra harnesses are two piece meaning that they have the plugs on the strut towers like OBD1 harnesses instead of having one driver's side plug and a green plug near the ECU like the "one-piece" OBD2 Civic harness. You can't use a JDM harness because it's RHD, and it will most likely to be cut and damaged anyway.

Since you are using an OBD2 harness, you DO NOT need to make any alterations to the alternator, injectors, or distributor. It's all plug n play. The old way of swapping on OBD1 parts or splicing to OBD2 harnesses is pure insanity. Buying all the adapters trades insanity for expense and added bulkiness of wiring.

THE OBD2 USDM INTEGRA HARNESS PLUGS INTO YOUR OBD1 CIVIC HARNESS AT THE STRUT TOWERS. There's one plug leftover on the OBD2 harness that you don't need. Just zip tie it out of the way.

At this point you have several options:
1: Get an OBD1 USDM manual P72 and plug it into your Civic ECU harness, add pins to your ECU harness for knock, IABs, and VTEC and run the wires to the engine. This way has long been preferred, however, OBD1 manual P72's are now hard to find and tend to be expensive.

2: Almost the same as option 1 but get an OBD1 automatic P72 and convert it to manual. Not hard to do and the auto ECU's are much cheaper.

3: Get a P06 or P28, chip it, flash it with a B18C1 tune, alter the circuit board to add IABs and VTEC (P28 already has VTEC). Pay someone to do this for you. The major advantage is that you can then get the car dyno tuned. Options 1 and 2 can have the ECU chipped and tuned as well, but if you are going to do that you should save the money and headache and just do option 3.

4: Use an OBD2 manual P72 with an OBD1 to OBD2 conversion harness. OBD2 P72s are cheap and relatively easy to find. The conversion harness is less common than the others but readily available from Rywire for $140. You'll have to bypass the CKF and add wiring for knock, but this is a simple procedure. You'll also have to have a secondary O2 bung added behind the cat converter.

5: Use a JDM OBD2 P72 with an OBD1 to JDM OBD2 conversion harness. Probably the cheapest and easiest option but most likely will not pass BAR in CA. Options 1, 2 and 4 should pass BAR, with 4 being the most legit and legal option.


I'm doing option #3 also since I scored a free chipped P28 when I swapped an HX engine into a CRX for a friend. My other friend is a professional tuner who is getting the ECU flashed for me and adding the circuitry for IABs. When I move to CA I'll put the OBD2 GSR ECU in and get the car BAR'd (#4). The swap is coming out of my 97 GSR so I already have the ECU, just need to get the conversion harness.

I think I will do a pictorial since Civic-EG doesn't really have one. I just need to finish swapping my VX engine into my CRX before the VX can get the GSR engine.

I'll be honest, that's a ton of information to take in lol I don't know how to convert and chip electrical stuff bro. I'm still learning how all this works but I did learn a thing or two. My current set up is OBD1 B18A1 from a LS integra and there are plugs that sat next to the strut towers. But this engine came from a old 93 DA Teggy. I haven't gotten ended the carpet to see what type of ECU I have under there now.

I currently have a OBD2 dizzy, the useless right hand drive harness and the obd2 p72 ECU

On the old engine I still have the obd1 ECU and the obd1 harness. But I didn't think before I acted and gave away the obd1 dizzy.

With everything I listed I feel like I have all the necessary parts to do it all. But with the first reply I got with the jumper seems pretty promising?

- Tue Mar 03, 2015 8:39 pm #352364 If you are already running an OBD1 LS motor in your hatch you can use the harness you have already and the ECU can be sent out to be chipped and converted to VTEC I listed two great sites that do that on my first post (phearable.net and xenocron.com). You will re-use your OBD1 alternator and injectors (They are the same 240cc injectors on an LS or GSR changing them will just save you from wiring). Also I highly suggest a chipped ECU over a stock OBD1 P72 as it will keep you from having to add a knock and O2 sensor (I listed a stock P72 as an option on my previous post, which it is an option just not the most practical).

Again like I said there is more than one correct way to do this swap these are just some options. I am basing my options for you on the parts you already have and what in my experience has always worked with no issues. The OBD2 engine harness (and a chipped ECU) is the easiest way if you are able to easily find one. Close to me Integras are damn near impossible to find in a junkyard and no one ever has the harnesses up for sale.

I am currently running an OBD2 B20b in a 95 hatch using most of what I suggested:
OBD1 B series alt (should already have)
OBD1 B series injectors (should already have)
OBD2 Distributor with Rywire conversion harness (Already have dizzy, harness is like $35)
D16Z6 Engine harness (You should already have and OBD1 engine harness you will just have to add VTEC)
OBD1 P72 with Hondata S300 (chipped from Phearable.net is $175, Hondata is $495 additional but you will be fine with just a chipped ECU)

If you want to save some money and take a shot at converting plugs over yourself here is the necessary info.

Distributor conversion:



OBD1 ECU pinout:


Shock tower wiring for knock, vtec, 02 sensor


And just to show you the injectors are in fact identical size wise so you are safe to just slap the LS OBD1 injectors in to save the wiring headache.
http://www.phearable.net/images/tech/stockinjectorsizes.html

And if you want to learn about chipping yourself check out here
http://wikitest.pgmfi.org/twiki/bin/view.pl/Library/WebHome
^There is a write-up on this forum by me on how to convert a non-Vtec P75 ECU completely over to a fully functioning chipped P72 if you decide to get into it

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[suspendedHatch]

- Fri Mar 06, 2015 5:06 pm #352427

I'll be honest, that's a ton of information to take in lol I don't know how to convert and chip electrical stuff bro.

Okay... my suggestion avoided any wiring and suggested you keep the stock ECU. I could have narrowed down the suggestions if I had had all the information. Good luck, bro!

- Mon Mar 09, 2015 6:38 am #352499

If you are already running an OBD1 LS motor in your hatch you can use the harness you have already and the ECU can be sent out to be chipped and converted to VTEC I listed two great sites that do that on my first post (phearable.net and xenocron.com). You will re-use your OBD1 alternator and injectors (They are the same 240cc injectors on an LS or GSR changing them will just save you from wiring). Also I highly suggest a chipped ECU over a stock OBD1 P72 as it will keep you from having to add a knock and O2 sensor (I listed a stock P72 as an option on my previous post, which it is an option just not the most practical).

Again like I said there is more than one correct way to do this swap these are just some options. I am basing my options for you on the parts you already have and what in my experience has always worked with no issues. The OBD2 engine harness (and a chipped ECU) is the easiest way if you are able to easily find one. Close to me Integras are damn near impossible to find in a junkyard and no one ever has the harnesses up for sale.

I am currently running an OBD2 B20b in a 95 hatch using most of what I suggested:
OBD1 B series alt (should already have)
OBD1 B series injectors (should already have)
OBD2 Distributor with Rywire conversion harness (Already have dizzy, harness is like $35)
D16Z6 Engine harness (You should already have and OBD1 engine harness you will just have to add VTEC)
OBD1 P72 with Hondata S300 (chipped from Phearable.net is $175, Hondata is $495 additional but you will be fine with just a chipped ECU)

If you want to save some money and take a shot at converting plugs over yourself here is the necessary info.

That actually helps a lot. I went on ahead and bought a mint condition GSR obd1 engine harness, a P28 ECU and I just ordered the jumper harness to avoid having to buy a new dizzy.. My new question is, do you guys know if the jumper harness will send wrong codes to the ECU, causing lag and difficulties?

- Mon Mar 09, 2015 6:42 am #352500

I'll be honest, that's a ton of information to take in lol I don't know how to convert and chip electrical stuff bro.

Okay... my suggestion avoided any wiring and suggested you keep the stock ECU. I could have narrowed down the suggestions if I had had all the information. Good luck, bro!

I just felt like it was easier to go ahead and buy a decent engine harness and a p28. All this cutting and splicing is way it of my league lol.

- Wed Mar 11, 2015 1:46 pm #352531

That actually helps a lot. I went on ahead and bought a mint condition GSR obd1 engine harness, a P28 ECU and I just ordered the jumper harness to avoid having to buy a new dizzy.. My new question is, do you guys know if the jumper harness will send wrong codes to the ECU, causing lag and difficulties?

It will not cause any error codes this is exactly how I am running my motor just plug it in and you will be set.

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