I know this has probably been covered, but I am fairly new to hondas, so that being said...

Ive got a d16z6 with a fully built head. I know that the idle is going to be a little rough considering the skunk2 cam. However, when Im driving and then shift to neutral the car's idle drops down to 850-950 and then immediately bounces back to around 1200rpm.

Sometimes after bouncing to 1200 it will drop to anywhere between 650-950rpm and stay there. There is no rhyme or reason to what number it goes to.

Other times it will drop to around 950rpm and then shoot to 1200 and then bounce between 1200rpm and about 1400rpm.

Im going to guess vacuum leak somewhere...?



Also, is it normal in Hondas for the idle to drop to higher than what the idle is set to when shifting into neutral and then dropping to 650rpm after the car has fully stopped?

thanks guys

 

I forgot to add

93 ex
NEW:
brand new built head
skunk2 cam
new valves, springs, retainers
dizzy cap, rotor, plugs, wires (full tune up)
fuel filter
master cylinder (not that that applies here)

no smoke coming from the car, white, black or otherwise. no fluid loss.

timing checked with a timing gun twice over the course of 3 days. Still perfect.

Idle adjusted at a shop where they are able to read rpm. I dont have a reader that works right now.

I think thats everything...

 

i have a rpm gauge f/s that works on all 3/4/6/8 cyl. motors
has the ivac been cleaned?
did you adjust the idle by the cable???if so loosen it back there is a idle screw..

 

Ive been searching for a while and I think Im going to clean the Fast idle and Idle air valves and check some sensors and then see where that gets me. Correct me if Im wrong, but the throttle cable should have 10-12mm of free play in it correct?

 

yes and yea clean your stuff

 

okay. done. Ive also adjusted the idle valve on the throttle body. Now I understand that I cannot accurately adjust the idle without a way to measure engine RPMs. However, my question now is, no matter how I turn the screw the engine still idles at around 1100rpm (on the guage in the dash.) What would cause this? Bad screw? MAJOR vacuum leak?


I'll turn the screw and the idle will go down. However while driving the car the idle eventually settles on 1100 rpm, give or take, and stays there. Any ideas? I mean, the idle screw is working - It just seems like the ECU is compensating or something and adjusting the idle back up to 1100.

 

You adjust the idle screw of a warm engine to 420 rpm with the IACV disconnected. Then replug the sensor and reset the ECU.

Have you properly bled the cooling system of trapped air using the bleeder bolt?

Take off the intake and let the warm engine idle. If you block the port in the throttle body leading to the FITV with your finger, do you feel air pulling through the port and does the idle speed drop?

Is the CEL on?