I have a cx shell (with everything but the motor pretty much) and I have a GSR. I have already pulled everything of worth off the GSR and have installed all of it onto the civic. I have already completed my engine rebuild and I’m gonna be dropping the motor into the civic tomorrow.

I have an OBD2 GSR motor, an OBD2 engine harness from the gsr, an OBD2 P72 ecu, and I have a obd1 - obd2a jumper harness.

I just want to make sure that I’m all set to just plug everything in, I don’t wanna miss anything. Do I need anything else on top of what I already have?

A lot of the wiring information that pops up on google searches from Honda tech is from like 2006 so I want to get updated and correct information that I am good to go

thanks guys!

 

Even though the OBD-2A GSR engine harness will essentially "plug into" the chassis harness plugs found in the engine bay on both the driver's and passenger side, looking closer will reveal that some wires on the engine harness side of the plugs do NOT exist on the chassis harness side. These would be VTEC Solenoid, VTEC Pressure Switch, IAB, Knock Sensor, and the Crankshaft Fluctuation Sensor. All of these wires would have to be ADDED to your chassis wiring from the ECU to the appropriate plugs in the engine bay. You will be missing MAJOR emissions related components that the OBD-2A ECU will be looking for that do NOT exist in your chassis... adding all of these will be expensive and challenging. I suggest you find an OBD-1 P72 ECU that will be "plug-n-play" in your chassis... and you will NOT have to wire the Crankshaft Fluctuation Sensor either since the OBD-1 P72 doesn't recognize this sensor. You can also sell your OBD-1 -> OBD-2A ECU jumper harness since it will not be needed.

 

couldn’t I just buy something like this?

https://www.ebay.com/itm/32503737807...mis&media=COPY

 

If you intend on using an OBD-1 P72 ECU (and NOT the P72 ECU that you currently have)... yes. That add-on/conversion harness does NOT include wiring for the CKF (Crankshaft Fluctuation Sensor), so you cannot use an OBD-2 ECU because it needs that sensor to function properly.

 

well I’m gonna have to wire in the ckf censor. I’m not buying an obd1 ecu

 

or just do the bypass trick

 

Then you're doing it wrong. Obd1 chassis, obd1 wiring and ecu.

 

If you keep the OBD-2A P72 ECU (because you don't want to spend $$$ to do the swap correctly), how do you intend to defeat the fuel tank vapor pressure and purge/cut vent valve codes ??? There is no provision in the fuel tank for the former, and your charcoal canister has no electronic vent valve, so you would also have a CEL for the latter.

 

You’ll have to move all of the obd2a fuel tank and evap stuff over to the civic as well, and add the rear oxygen sensor. You’ll also end up needing the dash harness and/or some creativity to end up with an obd2 diagnostic port on the car. All to end up with an ecu you can’t tune on. It’s far less work to make the obd2 engine harness plug into the obd1 chassis/ecu harness and use the obd1 ecu. Unless you’ve got some unknown emissions related reason to update an obd1 Civic to obd2b, I can’t for the life of me imagine why you’d go through all of that. Most straightforward route here is to add the vtec wires to the civic’s chassis side harness, do any other necessary rearranging, plug up a chipped/Hondata ecu, and send it.

 

nah it’ll work

 

With enough work, yeah. But for what?

 

would that cause the engine to run rough? Or is this just a concern for emissions and safety for registration?

 

mostly to spend least amount of money as possible

 

mine is a 97, it didn’t have the ftp

 

the least amount of money possible is to run obd1. Trying to keep an obd2 ecu happy with no cels will be more work, more parts, more wiring, more time, and hence more money period

 

You really think a $300 ecu is more expensive than the stupid route of trying to cobble together a way to get an obd2 ecu to work? Only to end up unable to run anything other than a completely stock engine.

Why do you think in 30 years of these cars being around you've never heard/read/or seen someone accomplish this for a b series engine?

Get an obd1 ecu or figure it out on your own.

 

https://www.ff-squad.com/technet/hybrid.92-95.obd2.htm

 

I vote obd1 route too. Especially if you are trying to avoid extra work and tuning anything.

 

Here’s one thing I should mention, I agree with you guys, I’d love to get an obd1 ecu, and I plan to, I would just like to get this thing started quickly, and I’ll get an obd1 ecu shortly.