Keep in mind I have my IAC hooked up with hoses...I am using an alum 3L split port manifold. Does it matter the length of the hoses?

Okay...here's the deal: I am going to start tuning my new set-up this weekend (3L turbo). it is the only code I have, and i have some Q's. 1st I believe it is associated with my unusually low idle (I can barely get it to idle on its own at about 400 rpm)

I have read sometimes it's a wiring issue...how do I tell? I want to know for sure before I go get an IAC...

I put 12v across the IAC and it does click. I put an almost brand new IAC from the donor motor in the plug (though not hooked to the manifold---it takes some modification to do so--) I still got the code. What do I look for on the wiring? I have checked the unit itselfas fasr as ohms and putting voltage on it and it tests fine.

So I guess I am assuming it is the wiring...is it the plug itself or the wires? I have tons of extra plugs I could splice in, but I hate to hack the harness if it is not neccesary.

I know my base tune may/may not affect the idle now, but the fact is that i still have that code. The wiring harness I am using came from a newer half the mileage SVT, so I assumed it would be fine. One ground will ground whe testing with a volt meter.

ANy ideas?

What is the actual written explanation of the 1504 code?

I don't have time to look it up and I can't help without it.

P1504 Idle Air Control (IAC) Circuit Malfunction

Do you have POWER and GROUND at the IAC connector?

If no you have an open wire or a blown fuse most likely..

How many mass tics are coming through at 800rpms? You might need to enter that value into your neutral idle air table. With all of your new plumbing the value you are getting might be too low for the ECU to compensate.

I'm guessing here so don't hate.

Not sure...haevn't done any datalogging yet...I will be checking the IAC wires today and then datalogging is coming on Sat.

what if I have the wrong IAC? would it really matter? the difference could just be the plastic plug...what do you think?

Originally posted by stilov:

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what if I have the wrong IAC? would it really matter? the difference could just be the plastic plug...what do you think?

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Dude seriously get a $3 test light, put the clamp on the negative side and the probe on one of the connector terminals. Then do the same but put the clamp on the pos side. If it lights up both ways you have a ground and power. Your IAC won't make a damn bit of difference if you have a broken wire or a poor ground.