i just drove my car around from having it down for the winter, and i just put an ls6 intake on it.. well i noticed when ever i put the car in neutral or stopped, the rpms would stay at about 1300 for a couple seconds then drop down to the normal idle... anyone know why this is happening??

 

When my friends battery was near dead his car did this(also after not driving it for a month or 2) Battery charged up and its fine now. Hope that helps

 

Sounds like it might just be still searching for where it wants to idle. I'd give it a few start and drives before I got worried.

 

mine did that and i think i had a slight vacuum leak somewhere, but i forget

 

alright, ill charge the battery even more, and give it some time, but if it continues ill look for a vacuum leak.. but anyone else know why it could be doing this?

 

The PCM. There are two tables that add airflow that can throw off idle. Throttle cracker and throttle follower. If you revs don't come down fast enough right after you get off the gas and put the clutch in (or after you rev the engine), then it's a problem with your throttle follower settings in the PCM. If you're coasting along with the clutch in and the idle will not drop until you come to a stop, that's the throttle cracker table. Chances are though, this is an issue with unmetered air entering the engine (ie vacuum leak) since you're still on the stock cam.

 

what can i do to fix the throttle cracker or the throttle cracker?? if that is the problem..

 

You need a program like EFI Live or HPTuners.

 

thanks for this info I have been having this problem forever and no clue what it was. mine will sit at 1500 or so rpms until I come to a stop and then it drops to idle.

 

Besides checking for a vaccum leak, sounds like it could be idle re-learn. Give it some more starts and stops and drives and see if it comes back to normal.

 

Man, mine would stay up around 2k or more RPM and my car will drive by itself when I put the BBK Intake on, I have to get it fixed when I get back home in a couple months.

 

The dead battery issue will cause idle hanging problems, but could not be the cause of yours. Mine was doing it like CRAZY (2000rpms plus), battery died the next day.

RIP Walmart Special, I hardly knew ye.

Will your a/c controls work? Does it switch from defrost to vent to floor?

 

well, i just recently took my a/c out... would that have anything to do with it?

 

There's a tiny vacuum line from the back of the manifold that powers the moving parts inside the a/c and heater. If you left it off, or it popped off, it could be your leak.

 

hmmm... i dont know what line ur talking about?? i think i know what little line from the back of the manifold ur talking about, but i dont know where the other end is...

 

It's right across from the brake booster hose fitting. It's about 1/8" and points toward the a/c area. The little vacuum line runs into the wireloom by the PCM.

 

probly a vaccum leak when i disconnected my egr and air i forgot to plug the one vaccum hose that went into the air solonoid???? on the driverside head....anyway my idle hung at like 1000 or 1200 ...plugged the hose...first drive perfect idle....just my .02 though

 

where on the drivers side head is the hose at? now its idling at 800... i really cant remember what it idled at b4... anyone?

 

i had the same problem even when you put it on D it lagged then it started moving, it was from the battery connections one of them was worn and rusted, After changing it the car idled fine and did not lag. so it might be something related to the battery or the connections.

 

Mine hangs up a little after i do a burnout and roll out of it...