My v6 idles weird. In the morning I start the engine it immediately runs with a turn of the key but idles around 550. Once warm it idles around 600 in drive and 750 in park. The engine take longer to start and tps is at .54 volts ....is this normal?

 

The IAC isn't working... You're supposed to cold idle about 1200 RPM and hot idle at about 8-900 when in Park/Neutral and about 650-700 RPM in a drive range. My engine did the same thing when the IAC was bypassed (thanks to the idiots that put my 3.1 in the car that didn't swap over the idle air pipe!) and again when the IAC didn't work because it was dead. If the idle speed actually RISES when the engine warms up, the IAC is suspect.

 

Location of the IAC valve? I have a carburated 2.8 i realize many have FI cars, however myc ar has a high idle in park and some say it sounds as if it is "racing"... sounds like its right about 1200RPM. I adjusted the "Screw on the rear flap in the carb" and now it idles nice and low in drive, so thats good.. Hot idle? Well, if its in park it still idles high one guy even said it sounds like it is "racing."

isnt second suspect a vacuum leak? how to detect? (And what did me screwing the mixture screw "in" accomplish?" it used to idle high in drive too. Not anymore.. my engine was a turnin fast for a long time, not as much so now, only in "P."

I have same issue. Car runs well, particularly when warmed up it sometimes takes a few minutes of weird hesitating to run smoothly. Thats my chime-in, ill follow for more info, thanks

 

I believe 1200 rpm is about right for carbed 2.8 in park regardless of the engine temperature...carbs aren't ment to idle down low because it operates off of vacuum.

 

1-1.5 grand is normal engine temp shouldnt matter

 

Thank you, i thought it might be "alright" now i need to figure out why my MPG is so low (though the gas gauge isnt really accurate at all lol)

... same on FI cars, this idle? My carb is in the minority, im sure. I noww have the micture screw more "in" too, thought it affected idle. It did for in drive, idles low now when not in park, and thats good

 

Carbs don't have an IAC as they regulate their own bypass air. Instead, they have something called a throttle kicker, which adjusts the position of the throttle linkage based on the ECM commands, similar to the way cruise control works. First thing I would do would be to pick up a small tach or something and find out what the actual engine speed is rather than just guessing. If the engine sounds like it's "racing", chances are you're probably running closer to 2000 RPM instead of 1000.