SR Idle Woes

[pacotaco345]

So a little bit of backstory, my motor (s13 blacktop) has always had some weird idle issues, idling high or low or being a bitch to adjust, idk. Just rebuilt it 2 weeks ago and for the first 3-4 days it idled great then over the next 2 days it progressively got worse (or higher). At first I could knock it down by revving it really quick but after a while it would just hover around 1.5-1.8k no matter what. Here's what all is done:

10 lb flywheel
z32 maf
greddy intake
fmic (no bov)
550cc injectors
s14 t28
tomei 256 cams
enthalpy tune
safc (it does nothing)
forged bottom end (stock compression)
I'm sure there's some other small stuff I'm forgetting

Things I've checked that are good:
vacuum leaks
tps voltage
coolant temp sensor

Other stuff:

I've always had an issue with the maf wiring, if I jiggle it it'll either make the car run normal or like shit. I couldn't find a definitive answer on whether or not to run the second ground to chassis or ECU so I just tied it into the first ground going to the ECU. I played with it some today and it seemed to knock the idle down a bit but then after a few minutes it just went back up. Maf wiring never made a difference in idle with the old setup, just in how the car ran above 2.5k.

I unplugged the tps today while the car was running, made no difference to the idle maybe even raised it by a couple hundred rpm if any.

Pulled the tube off of the IACV and pinched it/shoved my finger in it to plug it. From the amount of suck it gave (hehe) it almost felt like it was stuck wide open. I unplugged the IACV and it made no difference. With the adjustment screw all the way in it lowered the idle about 300 rpm but it was still crazy high. This made me think bad IACV but after I plugged all the tubes back in I accidentally bumped the maf and the idle dropped right back down to 850. I thought "sweet it was just the maf," went on a drive around the block and now the car idles at 1500 again.

Long story short, I'm stumped. help

[jscherf92]

For ~$40 replace your iacv. I had a similar problem, no amount of adjusting or troubleshooting seemed to work. Replaced the iacv and got it down to 800 in no time!

[OBEEWON]

If you have an after market intake manifold make sure that hose to the cold pipe isn't kinked. Actually no matter what manifold you have make can get kinked and give idle issues.

[ultimateirving]

It's your iacv man. They are so notorious for idle issues. It's either very gummed up or non functional.

[pacotaco345]

If you have an after market intake manifold make sure that hose to the cold pipe isn't kinked. Actually no matter what manifold you have make can get kinked and give idle issues.

Nah its definitely not that, tube runs straight back from the coldpipe to the iacv.

Looks like I'm going on a hunt for a good iacv

[ultimateirving]

Nah its definitely not that, tube runs straight back from the coldpipe to the iacv.

Looks like I'm going on a hunt for a good iacv

I went through about 3 before in found a trusty one and also look for one with the metal screw underneath, some came with plastic and is hella easy to strip

[pacotaco345]

Just an update for any of those who are wondering... I threw a different IACV on it and it didn't make a difference, played with the MAF wiring some more and it seemed to do the trick. It still wanders for idle every once in a while and drops pretty low or stalls sometimes. This weekend I'm going to re-do the MAF wiring and set the idle while the cars in timing mode and see if that fixes the stalling issue. It is nice to sit in traffic and not feel like a ricer all the time though.