my friend has a 96-98 civic dx coupe and has swapped a y8 IM on w/ a z6 throttle body. just wondering what the hole by the map sensor is for. is it a vacuum port that needs to be T off or can it be pluuged? also he is having idle problems too and we already checked out and cleaned the IACV. it idles 700 while warming up then slowly climbs to 1500 and drops back down 700, then repeats itself. the problems i've had with funny idles was cleaning out the iacv it always worked. any suggestions?

 

vac leak or possibly a bad sensor

 

have you tried to unplug the sensor on the iacv to see if it still has that rapid idle? try that.. it realy sounds to me like a iacv problem
if not it could be a vac leak or maybe your tps

 

if it was a vac leak... it'd idle shitty from the time u start the engine... check that iacv ----... this is what i do to see what the problem is... start the car, yank off ur intake hose, look inside ur throttle body. see 2 holes? put ur finger over one while the car is on.. see if the idle drops to normal. first hole didnt do it? try the other one... if nothing happens when u do this then ur problem is else where

 

It's my car that he is talking about. I tried what you said, taking off the intake and covering the holes, when I cover the top one, the engine idle drops down pretty low, the bottom hole just sucks on my finger.
What does this mean? What else can I look into?

 

If it sucks in your finger its a vacuum source and should go somewhere or be plugged. That's your problem.

 

It does go somewhere. to the FIV.

 

that area is all fine

top hole = iacv (so when plugged the car gets NO air and almost dies).

bottom hole = FIV or FITV (however u wanna say it)

clean out your IACV REALLY good. even consider takin the TB off and cleaning all the air passages.