EuroR_TSX

Hey everyone! I know there's a number of these types of threads floating around on HT, but I wanted to be absolutely sure on this.

Here's the details:

Car: 94' Civic Si Hatchback (OBD1 Chassis)
ECU being used: Hondata S300 chipped P28
Engine being swapped in: 2000 ITR B18C5
Engine wiring harness being used: 96-98 Integra GSR (My guess, because there's no plug for the crank angle sensor)

I've come across many threads that say you can connect the OBD2 (Engine side of harness) plugs in at the OBD1 (Chassis shock tower harness) plugs and all is good.

Here's an example... https://honda-tech.com/honda-civic-d...1-car-2884813/ Problem is, all plugs plug in here.

OK, now I've also heard people say that in some cases, you'll have some plugs that won't match up, but is also all good. As stated by Katman on FFS TechNet (.:FFS TechNet : Scenerio 2 : OBD2 Engine into an OBD1 vehicle :.), "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!" Haha, that's the part that has me thinking!

Here's what my shock towers look like:





Here's where my concern is...


Isn't this the plug for the fuel injectors?


Is this possibly for the charcoal canister valve? (NOT using anyway)


Questions:

1. IF THIS IS CORRECT, then the only thing I'll ignore is the knock sensor signal in the programing on the S300. Correct?
2. VTEC oil pressure sensor and VTEC solenoid, along with all other sensor/connector wiring will work just fine as plugged in?

I appreciate everyone's help, as I've searched, but no one has spelled it out like this completely.

Thanks!

ktang

iTrader: (1)

The OBD1 plug with the 4 pins is for the oxygen sensor.

EuroR_TSX

Well crap, that complicates things more. There's already an O2 sensor plug on the harness where it's supposed to be, behind the engine at the back of the header.

I assume that O2 sensor plug is wired into one of the two other shock tower plugs. Would I just run an extension cable from the shock tower down directly to the O2 sensor, and disconnect the one on the harness?

Also, I'm trying to confirm that wire pinouts will match on each end of the shock tower plugs. I need to find a Honda service manual to take a better look.

ktang

iTrader: (1)

I think the GSR harness (engine side) accommodates 2 oxygen sensors (one before and one after the cat). However, if your Hondata ECU only needs one of them, you just need to figure out which oxygen sensor plug would be used, and plug into that one.

If the one on the shock tower is the only one used by the ECU, then you could extend to it (you could buy the 4-wire extension, or make your own). If the one that you're already plugged into is the only one used by the ECU, then all is good. Maybe the Hondata ECU lets you configure/program which of the two plugs is used!

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I took another look at your 2nd pic; I'm assuming that you have a left-hand drive vehicle, and that's your clutch reservoir. I think the bottom-most plug is the one for the fuel injectors.

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The VTEC solenoid and VTEC oil pressure lines should be in the top plug of your 1st pic. I think that, as long as there are matching lines on the ECU side plug, you should be good (should be in the Si).

http://www.ff-squad.com/tech/wiring/...ktowerplug.jpg

What is the light purple line in the 1st pic (the one that is not going through the plugs)?

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This link might help for your last pic. It looks like the knock sensor line, which you're not using, is in the 6-line connector:

https://honda-tech.com/hybrid-engine...ctions-644434/

JRCivic1

Looking at the photos that you have posted, the 4-pin connector on the chassis side of the passenger side engine harness mating point IS in fact the four ground wires for your fuel injectors (brown, red, blue and yellow wires). You should have a matching plug on the engine harness side with the same wire colors in it. If you do not, it must have been cut off just under the non-OE tape... peel back the tape/protective convoluted tubing until you find the wires and then add them to make the connection. The 3-wire plug that you referenced has the knock sensor wire in the middle (red/blue trace) surrounded by the CKF circuit pair (white and red wires). If you are using a P28 s300 ECU, neither of these circuits are used, so you can ignore this plug.

O2 sensor wiring runs through the larger plugs that you have shown to be connected in the photos. The primary O2 sensor plug terminates just under the intake manifold, just to the right of the oil filter, and plugs into the O2 sensor there. The secondary O2 sensor wiring on a '96-01 Integra actually runs through the chassis floor pan under the center tunnel console... NOT in the engine bay. Your '94 Si hatch doesn't have this, so you do not have to be concerned with it.

What is the purple wire for that runs through the photo ???

EuroR_TSX

ktang, thanks for the info, much appreciated.

JRCivic1, dude you nailed it! I had this harness laying around and knew it needed some repairs, such as replacing a missing plug, a broken plug, etc. I didn't realize the injector plug was cut off, as the OEM tape was still taped up pretty high on the loom. When I did remove some of it voilà, there it was, 4 cut wires obviously missing the plug. I'm going to be making the repair and the harness will be all good.



THE PURPLE WIRE: haha previous owner for some reason tapped into the horn wire further inside the engine bay wiring, not sure why.

Another question: This USDM ITR engine has a line coming out of the back of the manifold, connecting to an electronic control valve, which would then lead to the charcoal canister. The problem here is that there's a little incompatibility in how I can connect the EG's charcoal canister. Take a look!

Original ITR stuff


ITR throttle body does not have that spout where you'd normally connect the main hose for the charcoal canister


Here's the EG's charcoal canister lines (Vacuum, and whatever the other one does)


I'm up for ideas here as to how to be able to connect this correctly.

Thanks again for the help guys, it's much appreciated as always!

JRCivic1

If you are located in a state that does NOT have annual emissions testing, then you would do the following: Push the small vacuum line into the large vacuum line coming off the canister off the back of the intake manifold. Leave the other line open to atmosphere... this might mean that you smell fuel on occasion while accelerating, but probably not. If the smell bothers you, you will have to get an older OE throttle body to replace your ITR one (with, not without the vacuum port at the 12 o'clock position)... most likely an aftermarket one like a Skunk2 Alpha that is the same size (or slightly larger) than the ITR one you have now. There may be a way to drill and tap the port on the stock T/B, but I have never done this so I cannot tell you what you might be up against.

You will also have to replace the plug on the purge/cut solenoid to a square clip instead of the round grey clip you have now. I was thinking you had it pictured in your original post, but I don't see it now. Anyway, the wire colors are red and yel/blk. You may have to lengthen these wires, so make sure that your new plug has plenty of extra wire length so you can make just one splice.

EuroR_TSX

Humm...not sure why HT dropped/lost my last post...but here it is again:

I've made the repairs, good as OEM new



As far as for the plug for purge/cut solenoid, I do have a black square plug that plugs right into it. The question is: How could I make it work? I assume I'd need an OBD2 ECU, and it probably wouldn't be feasible as I'm using an S300/P28.

Thanks again JRCivic1