f-bodyz28

got my swap running, and i went to relearn the idle.
i had the evap port blocked on my ls1 intake thats right behind the throttle position sensor. with tthat port plugged it fires and stalls. if i remove the plug it will fire up fine.
Im going to make sure that the orange wire going to the computer that controls the iac stays hot when key is off. but if that checks out could the IAC be bad? thats why its stalling with that plugged off? it also does not like to come to a stop the idle will drop down almost stalling if i dont tap the gas a little to make sure it does not. also starting up itll fire up and then rpms drop real low for a couple secs then jump back up before it levels itself out.

cypris09

iTrader: (1)

Kind of sounds like mine. Have to give it gas to start and keep running until it finds where it wants to be. Stopping isn't always that fun as it tends to almost stall. Heck backing it out of the garage and letting off the tho title causes it to want to die. Driving down the road at 55 though. She's pretty happy

f-bodyz28

I feel ya man. It's really annoying. I've checked for other vacuum leaks but thereshe nothing. Last night I was driving it and with the colder air it drove awesome even coming to a stop didn't seem to drop idle. I'm going to pull the iac out today and see what it looks like and try to clean it. I also had a pending code for throttle position but I don't know if its because of thag evap port not being plugged and it sucking in a bunch of air

R13_Braz

Mine is having/had a really hard time idling as well. Partly due to my huge cam, but also the IAC was bad. Even with a new one, it wouldn't idle on it's own after I gave it some throttle. Until I can get it dyno-tuned, what I did was tighten the screw that the throttle plate rests against, increasing the gap allowing more air in. Idles on it's own now.

Not the greatest solution, but it did work.

f-bodyz28

Yea see my cam isn't that aggressive so I'm not sure what the deal is.. I replaced the iac today, still nothing. Tried the "relearn" still nothing. Did what you did and move the set screw on the throttle body and it'll idle in park fine now but as soon as I put it in gear it'll die. But once I'm going it'll idle half way decent on its own. I'm thinking the same thing that I will need a pro tune and dyno. But it does seem to run really good when the motor is cold or in cold night air. No idles issues at all... maybe the flash to turn on my fans is set to high or my coolant temp sensor is bad. I guess regardless I need to go to a shop for tuning asap since this is now my daily driver

cypris09

iTrader: (1)

Yea, Texas speed said that as well (with the set screw) He wants to see my datalogs but said obviously every car is slightly different so before I do anything I need to datalog. My car idles fine even when you put it in gear. It's just that initial start up it needs some gas till it decides to run on it'd own.

f-bodyz28

Yeah I set my set screw back all the way down and then watched my throttle percent on my scan tool and set it for 3-3.5% open. Then set the throttle back to zero by United plugging it with key off, turning key in for a sec or 2 then turning it off and plugging it back in. It'll idle now around 500-550 which its suppose to be set at 650. It'll go into gear now and when I come to a stop it'll almost want to stall but catch itself. I know this is frowned on but my only other cheap fix for nowhat is slowly drilling out the hole in the throttle plate. So I'm going to try that after work

cypris09

iTrader: (1)

Oh wow. I haven't touched my screw and I think I idle around 750 or 850 not in gear. But I was told drilling out that hole more is frowned upon and playing with that screw a little/ better tuning would be needed rather than drolling out the hole

R13_Braz

Drilling the hole out is definitely not something I'd do. Pain in the butt to fix it afterward.

Mine was trying to idle at 850 and still having an issue with it. Think I'm going to have them bump it up to 900 or 950 just to keep it from dying on decel.

Messing with the set screw really did make a difference though. Went from killing itself to idling somewhat smoothly. Didn't really get a chance to see how much more it might need thanks to the lifters disintegrating.

f-bodyz28

Damn that's a bummer. But after work I pulled my car in, followed these steps I found on ls1 tech and reset my set screw and throttle position volts reading. Then drilled out the hole to 7/32 which is barely bigger. Idles awesome now. The iac counts are a little high but they get down to 40-60 I'm not gonna mess with it anymore besides getting an actual tune. I can post the steps I found if you would like? I didn't mind drilling since I plan on getting a new throttle body down the road .

R13_Braz

Sure! Can't hurt. Always looking for new info.

Won't do anything until I fish the lifter out of the oil pan, but afterward would be helpful lol.