IAC / ECU problem.. wtf?

gustavohuber · Post by **gustavohuber** » Thu Sep 29, 2005 2:06 am

Hi Everyone, I used the FSM's instructions to check the voltage and impedance on the ECU and IAC, nothing seemed that wrong, except that the 7v lines on the ECU rang in at 12v.. any ideas, or any ECUs/IACs for sale

BAC5.2 · Post by **BAC5.2** » Thu Sep 29, 2005 3:41 am

I have a brand new IAC valve for a Turbo Legacy for sale.

vrg3 · Post by **vrg3** » Thu Sep 29, 2005 4:43 am

That "7 volts" thing isn't quite correct... The voltage on those wires is actually changing very rapidly from about 0 to about 12, and whatever multimeter the guy writing that chapter of the FSM had gave him a 7-volt reading as its interpretation of that signal.

Project_Legacy · Post by **Project_Legacy** » Thu Sep 29, 2005 7:31 am

how much for the iac if that guy doesnt want/need it??

gustavohuber · Post by **gustavohuber** » Thu Sep 29, 2005 8:25 pm

I need one for a N/A legacy, though if its testing fine, shouldn't it be working fine??

Matt Monson · Post by **Matt Monson** » Thu Sep 29, 2005 10:42 pm

Yeah,
It should be working fine. And what makes you think the ECU could be an issue? I've got a '90 ECU I can send you if you want to try it out. You can pay me only if you keep it...

gustavohuber · Post by **gustavohuber** » Fri Sep 30, 2005 5:32 pm

No logical reason, just that after trying everything else, seems like a good last option. With the ECU unplugged, the engine cranks much smoother and rhythmically than with it in, presumably because of some sort of timing adjustments the ECU is doing, or who knows. Also, I realized I'd routed the cam sensor wire under the manifold, rather than around the outside. It's not crushed like I'd thought it might be, but its a tight fit.. could inductive interference be doing this?? Basically, I want to try a new IAC, a new ECU, and a new cam sensor, and if that doesn't fix it, just give up and either have someone else try to fix it, or sell it to someone who wants to/has space to tinker. As much as everyone's support keeps extending this rope, I really do think I'm at the end of it, finally.

vrg3 · Post by **vrg3** » Sat Oct 01, 2005 6:46 pm

With the ECU unplugged, the engine cranks much smoother and rhythmically than with it in, presumably because of some sort of timing adjustments the ECU is doing, or who knows.

It's cranking more rhythmically because every rotation is identical. When the ECU's in, you get some combustion, which makes some rotations different from others.

could inductive interference be doing this??

Doing what?

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IAC / ECU problem.. wtf?

IAC / ECU problem.. wtf?