bad idle hunting with smoky exhaust

[thor]

Hi all,
I just completed a complete engine rebuild on a 94 talon 4g63 NON turbo manual transmission and here is my problem:
upon cold startup, the engine idles fine, albeit at about 1300, then after about 2-3 minutes of running, it begins some pretty bad idle hunting from about 600 to about 1800. Along with this is some serious smoke which smells like the car is running rich coming out of the exhaust. (It doesnt smell like antifreeze at all).

what could this be? a little history on this engine: the previous owner overheated it to the point of melting the spark plugh boots onto the plugs. I bought a rebuilt block and head assembly, and I re-used all the other stuff- intake, sensors, throttlebody, injectors.
I replaced the O2 sensor with the engine swap so that shouldn't be it..

is it possible the computer is in limp mode? I havent set idle yet, but I tightened the cam sensor in place. I was going to set all that until I found this started happening.

could it be a bad injector? ironically I had bad seals on the injectors to the intake which caused a bad vacuum leak, but it seemed to idle ok although it ran pretty rough.

Its definately running mad rich just from the smell of the exhaust. It almost has a blue hue to it but it could still be the rings breaking in.. i don't know. I ran it for a half hour after assembly so the rings should be ok.

any suggestions or help would be appreciated. this is my first attempt at a 4 cylinder rebuild so I'm a little green here.
thank you!

 

[dei4ever03]

i dont feel like getting in discussion with the idle problem.. but when you are smoking out the exhaust you ARE burning something.

white=coolant
grey/black=unburnt fuel(rich)
blue=oil

 

[thor]

right. I understand that.
but i've had cars that have ran so rich that the exhaust smoked. it just smells like that with some oil mixed in because the rings aren't seated completely yet i think.
the combination burns the eyes. it has a grey color to it with blue that hangs a little.

fyi so everyone doesn't think i'm a newbie to engine building, i've built a dozen chevy and pontiac v8 motors.

 

[thor]

I may have found the problem for the idle hunting..

I have a factory service manual and I checked the IAC motor and I get resistance between 2 pins that there shouldn't be. I tested each set of pins per the manual and lo and behold I had pins 3 and 4 not activating one step. so it seems that the unit is bad. I will report back when i get a replacement one.

also upon measuring things, the Throttle position Switch isn't going completely to 0 ohms or thereabouts. i'm getting readings from 5 to 20k ohms and if I force it closed it gets closer to 0. it seems like it has a bad contact inside.

I still believe that the guy that owned this car got it so hot when he overheated it that it destroyed everything attached to the engine. this just confirmed it more.


as far as the smoking, maybe the rings havent seated yet. anyone got any tips for getting them seated? i'm using 10w30 oil. it's smoking like a banshee but it has a snappy throttle. it's a little embarassing driving it.