Hi,

I'm doing a OBD1 conversion and am having the IAC problem!

Now, my IAC is a 3 wire, which is what I want right?



Now mine, the blue/black wire, is already in B23, and I have no orange wire. So the only wire is B23, nothing in B6 or B15, cannot see an orange wire anywhere.

I have linked this back to the OBD1 ECU and B23 is linked to the correct pin on OBD1. But I'm still idling at 3k. When I put my OBD2 ecu back on, it works perfectly.

Please help!

Thanks

 

The Si came stock with a 2-wire IACV. You do NOT want the 3-wire - this is what everyone is converting from.

There is something up with your conversion harness or ECU (or the program burned into the ECU).

 

Hi Chris,

Its me again! haha, I sorted the last problem! Thanks!

Anyway, as you know mine isn't actually an Si, it's a euro VTi, I just assumed that it'd be the same as the Si.

Mine is definatley 3 wire. Damn!

It could be the program, because the OBD1 works fine when I cut the jumper, but as soon as I link back to the program burned on the EPROM it throws a solid CEL. Which then idles at 3k. I just assumed that it was linked in with uberdata the fact that I get the IAC problem as loads of other people over there have the same prob.

 

Well then, thats even more confusing: On your stock engine harness, you're saying you have a 3-wire IACV connector, but back at the ECU connector you have no such orange wire in place???

If you really do have a 3-wire IACV that is not being controlled correctly by the ECU, that is one big *** vaccum leak. 3-wire and 2-wire IACVs operate differently - both with power applied and without. What I mean is this - if you unplug a 2-wire IACV, it closes down, or should, and does not let any additional air bypass. A 3-wire IACV does NOT close down - if you unplug it, it just stops moving but still provides a staight shot for air into the manifold (thus the leak).

Plug in your OBD1 ECU, remove the intake arm and cover the hole leading to your IACV: This alone should bring the idle down to the normal range.

So if you plan on using the OBD1 ECU w/ Uberdata, you'll need to correct the IACV issue. I would also say you need to do the pin swap at the ECU....but well, I don't know how your stock ECU is controlling a 3-wire IACV without the correct wires being in the ECU connector.

 

Yeh, I see your point. My digital camera is at a friends at the moment, I'll get it back tomorrow and take some pictures.

Thanks

 

omg I'm being a bit dumb today! haha

Well, I was looking at the plug on the IAC but the one nearer the TB, which is 3 wire (Yellow/Blue, Red/black and Green/black), I then spotted the plug on the IAC which is underneath, this is 2 pin (Yellow/Black and Blue/Black)

It's the one underneath that I want right?!

Sorry for being so dumb! I'm still learning!

 

Right, I've had a look at the wires, coming from the 2 pin IAC. It's actually a Yellow/Black/Silver wire, which on the ECU goes to B9, which I make IGP2, a power source for ECM/PCM control circuit.

So it's obviously working like this for OBD2, but for OBD1 should I move this pin?

 

Well, B9 connects to some pin on the OBD1 side through the conversion harness....where does it connect?

ECU Pinouts

 

It connects to B1, which again, I make to be power input. Going on this, http://www.ff-squad.com/tech/w...t.zip thats how I make it to be power input.

So what you think? Move that one to somewhere else?

 

+12v comes through the Main Relay and then into a 'junction' connector. This junction connector then has more wires that feed the ECU (B1 and B9 for OBD2b), the injectors and the IACV. So no, you don't want to move the IGP wires as they feed voltage into the ECU.

With the 3k idle, just unplug the IACV. If the idle calms down, then you can narrow it down to either the ECU/programmed burned into ECU/IACV control wire is improperly placed in the conversion harness or is just directly grounded out(keeping the IACV wide open - big leak obviously).

Since the idle is chill with the OBD2 ECU - it can only be one of the above options.

 

Right, I unplug the IACV and the car doesn't start at all, turns over and it trys, but it just won't come to life.

So now what?!

Thanks for all your help, much appreciated!

 

Right Chris,

As per your instructions, started the car on the chip, went straight to 2k and just stayed around there, but always fluctuating. I removed the plug to the IACV and the engine just cut straight out.

Is this a good thing or a bad thing?!

Thanks alot!