alright my 92 prelude sr has a pretty bad idle after it warms up it starts getting the popular bouncy idle(fluctuating up and down). first thing i did was clean the EACV screen, no luck, then i took off the fiv and turned in the white valve with the spring all the way in, no luck. so then i adjusted the idle screw, no luck.bled the cooland couple times too, nope.

some thing i did notice was when you take off your air intake, in the TB port there are two holes, bottom goes to FIV top goes to EACV. FIV hole does not suck air. but when you cover the top one (EACV) the idle levels out fine. also mabye there is a vacuum leak also bacause when you cover the entire air intake port with your hand it doesnt stall the the car, it just lowers the RPM significantly. the bouncy idle also goes away when you unplug the EACV.

any ideas?

i read you could block off the eacv by sticking cardboard in between the EACV and TB, would this work? would it cause harm?


also can anyone explain why the idle goes back to normal when i unplug the iacv the idle goes back to normal? also stops the bouncy idle when i put cover the iavc hole in the im where the air intake slides over?

 

could be an intake manifold gasket leak, trying spraying carb cleaner around the intake manifold while the car is running to see if the idle changes... I had the same problem, this was my diagnostic, and I had to replace the intake manifold gasket... good luck.

 

check tps i've had excacty the same problem