Here's the setup:

1996 Civic LX shell and emissions components, 1998 GSR ECU, SiR II B16 (Converted to OBD-II)

I'm getting a 450 MIL code, but all I see for the evap system is a solonoid on the intake manifold with power+ground connected to it.

How does it know when the evap system isn't working?

I was thinking I may need to buy a 96 Civic LX ECU because it had different components than the Acura? Please help!

 

The only 96 Civic that came equipped with a fuel tank pressure sensor was the Ex model. The 98 GS-R ECU is definitely looking for an FTP but can't find it because your car doesn't have it. If you try and use the Y7 ECU (which is what your car came with stock, correct?), which controls a 3-wire IACV, then you've gotta figure out what to do about that now since your B16 uses a 2-wire IACV.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EE_Chris &raquo;</TD></TR><TR><TD CLASS="quote">The only 96 Civic that came equipped with a fuel tank pressure sensor was the Ex model. The 98 GS-R ECU is definitely looking for an FTP but can't find it because your car doesn't have it. If you try and use the Y7 ECU (which is what your car came with stock, correct?), which controls a 3-wire IACV, then you've gotta figure out what to do about that now since your B16 uses a 2-wire IACV.</TD></TR></TABLE>

Correct, I had a D16Y7 with a P2E ECU. I think my best bet is just to wire up a 3 wire IACV and use the P2E ECU until I pass emissions.

What's the third wire for on the 1996 Civic LX IACV ? (The one I have now is 12v + Gnd)

 

ECUs that originally controlled a 2-wire IACV will never control a 3-wire IACV and vice-versa.

The physical design of a 2-wire IACV is such that that is all it needs...a simple +12v, while the ECU completes the ground side as you mentioned. Well the physical construction of the 3-wire IACV uses a rotary design that as it rotates, it opens up more and allows more air into the manifold to sustain idle.

When unplugged, it doesn't shut down like its 2-wire cousin. The 3-wire uses the same +12v but it uses two control lines that basically play tug-of-war with the rotary piece.

You can read more about it HERE if you'd like.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EE_Chris &raquo;</TD></TR><TR><TD CLASS="quote">ECUs that originally controlled a 2-wire IACV will never control a 3-wire IACV and vice-versa.
The physical design of a 2-wire IACV is such that that is all it needs...a simple +12v, while the ECU completes the ground side as you mentioned. Well the physical construction of the 3-wire IACV uses a rotary design that as it rotates, it opens up more and allows more air into the manifold to sustain idle.
When unplugged, it doesn't shut down like its 2-wire cousin. The 3-wire uses the same +12v but it uses two control lines that basically play tug-of-war with the rotary piece.
You can read more about it HERE if you'd like.</TD></TR></TABLE>

Interesting. I don't suppose you know where to find a diagram of the P2E ECU pinouts for the IACV? It sounds like this system has no way of knowing when it's not plugged in unlike the GSR system with a fuel tank pressure sensor?

 

This is exactly the problem I'm having.
http://technet.ff-squad.com/code91.htm

I bought a 96 P2E ECU today, but won't I get IACV errors when I plug it in? Is it even possible to make a 3 wire IACV work with a B16?