Crovax

Hi All,

I am a long-time watcher of this forum, and typically I have been able to find everything to answer my questions just by browsing the forum. Thus, I have yet to post a thread or anything else. However, I am running into something that I have not seen specifically addressed yet (forgive me if this has indeed been covered, I feel like I did my fair share of digging on this topic).

Now then, I am in process of swapping my old D17a1 head from my 2003 Civic LX 1.7L 5spd MT to the a2 head. The main reason I am doing this is because my old head is basically scrap (for a number of reasons) and I happened to have an a2 (and another D17 block, but just swapping the head for now) lying around.

So I know that my stock ECU does not have the means to deal with the VTEC signals without some sort of modification. It seems the most popular choice is using a vafc2 controller, or to swap ECU's with an EX model that is compatible with the VTEC signal (just need modding for O2 sensor with that method, I believe). I don't particularly want to drop $200 on a vafc2, and I don't want to drop who-knows-how-much to reflash the ECU at Honda.

So with all that, I remember reading a while back that if you're not using the vafc2 controller and you want to continue to use your stock ECU, you would just tie the solenoid wire to pin B12 (for my model year) on the ECU. That doesn't seem 100% correct to me; isn't the ECU still not "smart enough" to know when to turn that on and off? What about the pressure switch?

My plan (I guess) is to run the positive wire from the solenoid to pin B12, and the positive wire from the pressure switch to pin C10 (according to this diagram, assuming my ECU is OBDIIb), while grounding the negative leads. But does that really work? Isn't the ECU still not "smart enough" to know what to do with those signals? Or is it that the LX model ECU's are indeed "smart enough", but just don't have the signal/hardware?

Any help on this would be greatly appreciated! Please keep in mind that I am looking for an ALTERNATIVE to using a vafc2 or getting a new ECU and harness. I am well aware of those solutions, but they are currently above my budget for getting this car running (I can just buy an a1 head for around the same price and slap it back on - that's actually easier but I would like to actually get this VTEC head working since it's otherwise collecting dust in my garage).

Also, I wanted to throw this out: I remember reading somewhere (can't seem to find it again) that some people were actually running the solenoid wire to a momentary button in the cabin, effectively allowing them to trigger their VTEC at will. Is this also a "viable" (I won't say "acceptable" lol) solution? I'm thinking at that point, you wouldn't need the pressure sensor signal (unless it throws an engine code or something). I would prefer to actually wire the signals to the ECU if mine is indeed compatible, but it sounds like this method could be a last resort (or at least get me going until I get a proper controlling method). If anybody has some info/insight on this as well, it would also be greatly appreciated!

I think I gave all the necessary info, but please let me know if I left anything out in regards to this call for help.

TL;DR - For a 2003 Civic LX 1.7L 5spd MT receiving a D17a2 motor, is it enough to wire the VTEC solenoid and pressure switch to the stock ECU in order for VTEC to work properly? Alternatively, is it enough to wire the solenoid to a momentary button that I can trigger at will (last resort)?

Thanks!

mac25

I think you may be a bit confused.

As far as I know the manual ecu for a non-vtec vehicle cannot run a vtec head.

The wire is if you want to use your stock harness and run a wire to the vtec ecu, rather than swapping the non-vtec harness to a vtec harness.


Swapping the ecu is really, really easy!
I did it for my auto to manual swap.

You will need a scrap yard vtec manual ecu, no key, no ignition.

Pull the glove box out, remove the metal bracket that runs across the back of the glove box (you'll see it when you remove the glove box, it's like 5, 8mm bolts).

There will be a plastic part of the dash which will sit in front of this metal bracket. You do not need to cut it like some people say, just bend it a bit, it will bend back later.

then unplug the wires that go to the ecu.

Then there are three (I think) bolts that hold the ECU in.

BEFORE you swap the ecu drive the car to honda with as much of this process complete, without swapping the ecu itself, as possible! then when you get to Honda they can easily drive the car into the work bay and swap the ecu as they re-code your key to match the new ecu.

This will save you a towing bill and labor from Honda to swap the ECU.

ezone

This.

Don't connect the VTEC stuff at all, because the original ECM can't do anything with it.



If you wish to run your own wires so you can connect it to a pushbutton switch for manual operation or for later connecting to a standalone controller, that's fine.

Crovax

mac25 - Thank you for clearing that up for me, that makes much more sense now! So about how much did the junk yard ECU cost you? And how about the ECU flash at Honda (assuming I get it all ready for them as you described)? Just some ballpark numbers will do, I just would like to get a feel for how much more I need to spend (in other words, how many roses to buy the wife lol).

ezone - Cool man, thank you! Do I need to do anything with the pressure switch? Or is that really just to tell the ECU if the VTEC is "ready" so to speak?

Thanks for the replies, I'm glad I decided to finally post before going crazy with my ECU. lol

ezone

Your current ECM cannot operate the VTEC solenoid, therefore it cannot use the pressure switch on the VTEC valve either. Ignore both parts completely.......
unless or until you want to connect it or you want to go through the hassle of making ECM for an A2 engine work.


Programming fees will vary, probably by a lot. At my dealer it's a flat 1.0 labor charge (our labor rate is over a hundred bucks an hour) for connecting the scanner and doing anything at all with it. Other dealers may be more or less than that. Call around and ask.

If you have any well equipped locksmiths local to you, they may be able to do it too. Call and ask. (my local locksmith only has equipment for GM/Ford/Chrysler)

Same goes for a well equipped independent Honda specialist, might have the equipment necessary to do it. Call around and ask.

When you call to ask, you are wanting to know if they can program Honda keys and immobilizer system--- because you are wanting to replace your ECM.

You can drive the car to them on the original ECM, and swap the units in the parking lot ---but ask first so you can park the car in a place most convenient for them to program it. (My scanner setup is most convenient when I'm within range of our WIFI)



Also....someone in the past posted in this forum about finding a (low priced) tool that could program Honda and Acura Immobilizer keys, but I think it may have been using Chinese clone software.

mac25

Pressure switch requires a "standalone controller" as Ezone mentioned... that will cost you about $1500 (kpro standalone tuneable ecu + cam gear + tune).

Im' in Vancouver Canada the ecu cost $75 the tune for the key cost $120.


Remember you will also need to swap the header, downpipe, and cat. and run longer wires so the d17a1 O2 sensor can mount into the d17a2 cat.

or at least most people do

I'm really not sure what would happen if you left the stock setup for the exhaust on the d17a1 for the new head. Ezone help please =D

ezone

IMO it's a lot easier to leave it all alone. A1 manifold bolts to the A2 head just fine, no O2 sensor wiring to screw up, most people would never notice any difference in performance unless they run ***** out all the time.