My buddies car bogs out and misfires until the engine is fully warmed up. No CEL's and after its fully warmed up runs fine. What can be the cause, what should i check or replace.

 

BUMP

 

What type of car is your buddy driving? Make/Model/Year.

Sounds like a fast idle thermal valve or it could be low coolant. I'd need to know what engine and throttle body set up is being used to take a better guess.

 

96 EK b16 stock TB. and its not the IACV it was messed up and replaced with a good one.

 

How does it start/idle cold with the IACV disconnected?

Did you bleed the coolant system after you changed the IACV?

 

never tried that,yes

 

 

o2 sensor?

 

woudlnt a faulty o2 sensor throw a code

 

not all the time, usually you would see heater codes. but..
af could be lean till o2 heats up.

does it missfire badly?