Hey everyone, doing a sohc zc and manual conversion in a 00 civic ex. Swap is all done, running the correct p2e ecu. Followed the instructions hondapartshero posted, still throwing IACV code. Swapped in a known good IACV, same issue. Anyone have advice?

 

A P2E uses a 3 wire IACV regardless of trans type so if you switched to 2 wire it's going to throw a code. Manual trans P2P uses a 2 wire.

 

well *****. the sohc zc has a y8 style manifold with a two wire iacv. any ideas how to make it run right?

 

The American EX trim Civic is the same as the Canadian Si...which means you originally had a D16Y8 in your car. Which means you have a D16Y8 harness and ECU, correct?

Oh wait, you just did an Auto to Manual conversion...?

Why don't you use a chipped OBD1 ECU instead with an OBD2B-to-OBD1 conversion harness? The P28 looks for a 2-wire IACV also. Or you can use one of the many other OBD1 ECUs is you add the VTEC components into them, like a P06 or a PR4. That's what I did when I put a D15B VTEC into my 2000 DX hatch.

I had to change my harness....if my memory serves me right (this was years ago), one of the 3 wires isn't used anymore and can be taped up, and one of the other wires needs to move one spot over on the harness.

 

Install a 3-wire IACV and switch back the 3-wire pinning at the ECU and IACV.

 

That would work too...but isn't the SOHC ZC a VTEC engine? and isn't the P2E ecu an OBD2 non-VTEC?

 

obd-2= 120hp non vtec. yes, the car originally had a y8 AT. i bought it with a rod thru the block, put the zc in it, and converted to manual. the harness is the original y8 AT harness, and the ecu is the obd2-b manual p2e.

 

Yep, as nub pointed out, all P2E ECUs will expect a 3-wire IACV.

 

Oh ok. See these were the details you should have included in your original post. Because there are 3 different ZC engines. and when most people refer to them, they are referring to the OBD1 VTEC version with 128 HP:

~~~~~~~~~~~~~~~~~~~~~~~~~~~~

SOHC ZC VTEC

VTEC
Found in 1991–1993 Honda Civic Ferio EJ3 (JDM)
1992–1995 Honda Civic EJ1 (JDM)
1992–1995 Honda Domani MA4 (JDM) Displacement : 1,590 cc (97 cu in)
Bore and Stroke : 75 mm × 90 mm (3.0 in × 3.5 in)
Rod Length : 137MM
Rod/Stroke : 1.52
Compression : 9.2:1
Power : 128 hp (95.6 kW, 130 ps) at 6,600 rpm
Torque : 107 lb·ft (14.8 kg/m, 145 Nm) at 5,200 rpm
Redline : 7,200 rpm
Fuel Cut : 7,300 rpm
VTEC Switchover : 5,500 rpm
Fuel Control : OBD-1 MPFI
ECU Code : P70 (Domani), P91 (Civic Coupé), P29

 

problem is it isnt as simple as just swapping out iacv's. the auto y8 one that i have is tb mounted, not on the back of the intake manifold.

 

i did. and there are more than 3 zc's, they stamped zc on everything lol.

 

No way to mount a 3-wire on the IM?

 

i don't think so. mounting tabs are in different spots. the y8 iacv attaches on the bottom of the throttle body and looks like a fitv. swapping manifolds isnt really an option, either. 00 has the cold start assist holes that i am not dealing with

 

You can JB weld or tap bolts into the FIA ports of the 00 IM - not too hard. Then you can use the Y8 TB and 3-wire IACV.

 

I still think you should use an OBD1 ECU with a conversion harness...

 

This would not pass emissions testing in some states. Not sure if that's an issue for the OP.

 

very much is. the zc is so similar to the y7 that the p2e is my best bet anyways

 

hmm. what if instead of swapping manifolds, i swapped throttle bodies and blocked off the rear iacv mount on the current manifold? i ask this because the y8 i pulled had low miles and i would like to keep the head/manifold together as a set for sale/future use.

 

Okay, so what is stopping you from using the entire D16Y7 intake manifold, throttle body, and sensors, including the IACV?

I know it is the absolute worst designed intake manifold in existence, but hey, if it works...why not?

 

Ah ****, I just remembered you had a Y8 before...which means you will need to buy these parts at the junkyard...

Oh well, still an option to consider.

 

If you have the throttle body with the IACV mounted on it (3 wire) swaping it on would be the easy button.

A couple of things to note:

The throttle body with the 3 wire IACV has a specific gasket different than other other OBD2 TB gaskets.

If the existing 2 wire IACV is in good condition you can leave it in place. The valve is normally closed so without a signal it will be like it's not there. If the seat for the plunger is deteriorated it could leak which would be a vacuum leak causing a bouncing idle. A block off of you choice would be the next step.

P2E ECUs expect to run 190cc injectors, Y8's run on 240cc. 190's can be ID'd by a emerald green pental cap, 240's are yellowish.

 

appreciate it, nub. i swapped in the correct injectors from my parts pile. i do have the tb, i will probably put vacuum caps on the iacv just to be sure. now its off to the junkyard to snag a new three wire connector. the OG one was heavily corroded and the orange wire broke at the connector.

 

The vacuum caps aren't necessary. The ins and outs on the IACV are for coolant. Being in the the Northern part of the US you'll want the coolant lines hooked up. These keep the IACV from frosting/freezing in the colder months.

 

i meant the old one that would be left behind on the back of the i/m. ill need to reroute the coolant lines from it to the t/b mounted one