Int. high Idle...?

[JAWS]

When I start the car cold in the morning it idles at 1200. Sometimes it drops to normal, around 700 sometimes not during my 25 min. commute.
When I restart the car (warm) it will either idle at 1200 or 700. I made a bunch of stops on my way home from work Fri. and each time I restarted the car it was the other way from how it was when I stopped.
It seems to run rich, and MPG is down 3 or 4 from normal.

The only possible thing that I know of is a small crack in the intake elbow right before the throttle body.
:1zhelp:
Any trouble shooting tips are welcome.

88NA, 5speed, 190K

 

[Fuzz420]

Check you coolant level.If your low the car take longer to idle down once at operating tempature

 

[JAWS]

I guess I should un-bypass the heater valve...DUH. Coolant level has checked normal though.

 

[Bishop92t]

The car is supposed to idle higher when it's cold so it can get to operating temp faster. Once it's warm if it's idling high it could be any number of problems. Reset the ECU, drive it around a couple days and recheck the codes.

The low gas mileage may or may not be a separate problem. Fix that intake leak, it could be causing part of the problem. Heater valve shouldn't make too much of a difference, other then making the car take a little longer to warm up.

 

[935motorsports]

Check the green EFI sensor. When that is bad, it can cause stange idle issues.

Also check engine codes.

 

[JAWS]

What is the green EFI sensor?
Got a code 51, and the little leak in the intake hose is much worse then I expected. Right along one of the molding seams in the elbow that goes to the TBody there is a 3in crack!

 

[JAWS]

Fixed the hose and the TPS...which cleared the 51.
Still seems rich. I'll re-check the timing when I get it home.