Ok guys, so I think I’ve gone through every thread I could possibly find on idling issues. So, my initial thought was the IAC. Removed it, took off my UICP, and clean whatever I could clean inside the tb. Mainly the passage ways. Also got a new one on the way. Re-installed it, I wanna say it helped a little? But, maybe I’m just saying that to make myself feel better lol. So, at start up on full temp, the car idles fine. Around 920-980. The issue only happens after I’ve driven the car and idle drops to around 600 rpm and wants to die, but doesn’t. And I noticed when I turn on my headlights it drops more consistent. So today, I checked my voltage. Under full load, voltage was about 14.3-14.4, when the fan comes on, it drops down to 13.4-13.6 and then idle drops to 830 rpm. Could the radiator fan be my issue and drawing too much power? Radiator fan control module problem?

 

Try turning the BISS screw open, i think it's clock wise, on top of the throttle body. Small increment turns like 1/4 turn then observe idle. Use a short Philips screw driver and be gentle the screw is plastic and strips easy.

Voltage seems fine, when my engine bay gets hot in SoCal summer heat my voltage dips to 13.6. Check ground and positive connections for corrosion? I use sandpaper to clean the contact points

 

I just changed out my negative cable. Bought an extension because the original was broken. I’ll sand out the positive terminal, does seem a little corroded. Just changed out the alternator and cleaned the MAF and helped out a lot. Haven’t driven it yet so I’ll have to do that tomorrow. As for the BISS, wouldn’t I need evoscan to accommodate that? Everything I’ve read on the BISS, people adjusted but used evoscan to adjust the ecu? Or something like that.

 

Yeah, that's not the right way to adjust the BISS. Evoscan is the recommended way. Worst case scenario, you can disconnect the harness and set it to your target idle. But that's a last resort.

 

Disconnect what harness?

 

The one that plugs into the IACV. Then adjust the BISS so that the idle is at its target. It's not perfect. But it's better than just randomly messing with the BISS which is the wrong way to fix idle issues.

 

FWIW, do not clean the "gunk" from the inside of the TB. It's actually a sealant to keep air from getting past the butterfly. If you remove it, you will have idle issues also and have to re-coat it with 3m spray.
If you already knew this, then never mind

 

Haha yea I know about the black coating. Thank you tho. Just drove the car today, Idle seems a lot better. Dropped to 800 once, but, maybe ‘cause the ecu is re learning itself. Gonna drive it around more within the next couple days and see what happens. If the alt isn’t the problem, MAYBE I’ll try out the Biss. But, I’m pretty hesitant on doing so lol

 

Yeah, if you reset the ECU, etc then give it some time. Is the idle dropping when the radiator fan kicks on or at random times?

 

Yea it was before I changed out the alternator. It was dropping about 10.2. Going from 14.6 to 13.4 and sometime less than that. Now that I switched out the alternator, I’m getting a consistent 14.1 to 14.5. Since being switched out, the idle has been better. Along with cleaning the MAF and passage ways inside the tb for the IAC valve, Idle has gotten better all together. After I drove the car today, Idle only dropped to around 800 once, but, like I said, maybe because the ecu is trying to re learn itself. My last resort is to try the BISS, but, that’s my very last resort which I don’t really wanna mess with. Gonna drive the car around more and see what happens. I also got a new IAC coming in as well.

 

I mean dropping 1.2

 

If you have a way to data log the IACV, that would let you know right away if you need to adjust the BISS. Anyone around you that can help you out?

 

Sadly, no. My tuner is about 2 hrs away and is always busy along with myself. And I don’t really know anyone that runs evoscan.

 

Crap. If you can score a Tacktrix cable, we could walk you through enough to check the trims.

 

I’ll look in to a Tactrix cable. Funny because tactrix is located here in SF lol. I’m gonna drive the car around more today and let’s see how the idle goes. Keep you guys updated.