OBD2->1

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N

Nick7

Member
I have 6th gen Civic Hatchback, OBD2 (year '97).
Now, the problem is engine is 1.4 (D14A4), and ECU is P3Y (same wiring as P2K).
I hear you: why not just OBD2->1 conversion harness? Reason: My ECU has only 2 plugs. They look like OBD1, but are OBD2, and to add - it even fires injectors in pairs (1+4, 2+3) - only two wires go out of ECU for injectors.
So, most of plugs are 'unusable'.
What I was planning is to get complete OBD1 wire harness, and replace existing.
How big of a problem will that be? - I plan to put OBD1 engine (B16A2) aswell to get along with that. What I'm worried if there will be other possible problems?
 
Originally posted by pissedoffsol@Nov 17 2004, 10:52 AM
you're looking at a huge re-wire. everything in the dash will probably have to be re-wired.
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iow more work than its worth just use the conversion harness and cut down as much wiring as possible
 
plus, obd2 civics use a 1-piece harness. obd1 civics and integras use a 2-piece harness. its going to be a HUGE wiring mess.
 
Yah... I know it will take some effort.
Problem is I'm from Croatia (Europe), and you wouldn't belive how hard it's to find friggin' wire harness for OBD2 (not to mention 1.6 engine, be it a D or a B ).
So, now I have 2 choices: to get OBD1 harness, and re-do them, or wait for month, two.. or so, to order used harness from e-bay when becomes available..

But - as I'm already very impatient....

So, if I go on with OBD1 wiring, what problmes can I expect?
All engine sensors, etc fits, since engine is OBD1, I can get both fuse boxes from OBD1, so connectors for them fit, aswell as P30 ECU.
Now, I guess we come to part that don't fit -> I suppose some/most other in dash connectors might be different. Also, since it's 2-piece harness - does one part go to engine from left, one from right side? Will I need to make a new hole thru firewall?
Is it more-less enough to get all connectors, cut ones that don't fit, re-solder different (offcourse, with proper pinning/wiring), and make it work?
I am good with electronics, etc.. so I'm not too affraid of soldering, cutting wires, re-wiring, etc.
I suppose I can get car going pretty easy this way, but rest of wiring (gauges, etc) might take some time to re-wire.

... or am I into more troubles than I expect?

(any pointers from some1 who tried this, some thread, web page, etc? - I couldn't find any real info on this)
 
getting the motor wired to the ecu won't be a big deal- its everything else thats going to be a problem. your dash, cluster, and all that may very well not be compatible. i really don't know. i've never seen a 2-port obd2 ecu before. hell, we don't even get the d14 here.
it also sound slike the way it fires is that you may have to do a dpfi to mpfi fuel conversion- im not sure.

honestly- i'd just keep the d14 and throw a tiny t20 turbo on it to give it a little more pep. its probably easier in the long run.
 
.. I already did that :) .. Have Garrett T2 on it, running 8psi (have it already for approx one year)

And D14 is MPFI, but fires injectors in pairs.. - yeah, it's screwed up thing... and that's the reason for my headaches. I cannot put different engine and do simple OBD2->OBD1 harness conversion due to this, and lack of compatible OBD2 wiring harness is another problem.

From my understanding, as you said - engine shouldn't be the problem to start, and drive, but everything rest might be problem.

Since it's possible to use OBD2->OBD1 conversion harness, this makes me belive it would be OK to simply rewire connectors that are different - voltages, impulses, etc... all should be compatible, talking now primarily for cluster.

As I will have both wire harnesses - my old OBD2 (whatever type it actually is), and OBD1 -> what was my plan was to get car going with OBD1 harness, and afterwards re-do everything else -> cluster, and all other in-dash wiring.
What makes me belive I can do it is simple because it is (at least I belive it should be) compatible, as far as electycity, and signaling goes.

I know I might be facing some major wire harness mess :) but I belive I can do it.

What I wanted to know if anyone has some suggestions if they did anything like this, other troubles I might get into, or any good advice.

My main concern is now just after swap to get car going -> so all sensors, and engine works OK. Afterwards, I can do re-wiring as needed... most important is that engine runs.

PS: I'm not being ignorant that this whole thing might be really messy... but at this point it seems like only way to get that thing (B16A2) into my civic...
 
Just get an OBDI engine harness and uder dash harness. It is not that big of a deal, just have electrical diagrams for both cars. Even if you splice into the under dash harness, it is not the end of the world. Just make sure you solder and shrink tube every connection and take your time....you will be fine
 
wow, i wish i could even find an obd 1 b16 a2, im stuck with switchin over my obd 1 sol, to obd 2, are obd 2 engines not easy to find over there??

best of luck bud, sounds like you are in quite the pickle!
 
OBD2 B16 is very hard to find here... same goes for D16Y8 (even harder, LOL!).
Y7 can be found a bit easier, but still 'not that easy'. They arent that common here :(
Most Civic's are either D14 or D15. Funny thing is that D15 here also share same OBD2 - 2 connector ECU as mine. Go figure.

Anyway, been reading thru service manuals past few hrs.
Yep... major rewiring will be needed. Almost all underdash connectors will need to be re-done, but it doesn't sound impossible :)
It will take some time, tho... anyway, as I already said - most important thing is to get car rolling... everything rest can be done with some time.

nfn15037, good said... also when I solder I *always* use heat shrink tube!
 
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