I have a b18b1 in my 89 crx and i put a new IAC on it but it did not fix it. what else could it b.

 

how bought a vacuum leak? look around do you hear any hissing or feel any air coming from anywhere?

 

there r none

 

I've had this 3 times on 2 different motors:

1st: bad intake maqnifold gasket causing a VAC Leak
2nd: Don't know, just went away
3rd: Idle Screw backed out raising idle, ECU tries toadjust back to Ideal, over compensates, drops too low, bounces back up. Turn is screw to adjust idle, all is good.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bumblezc &raquo;</TD></TR><TR><TD CLASS="quote">
3rd: Idle Screw backed out raising idle, ECU tries toadjust back to Ideal, over compensates, drops too low, bounces back up. Turn is screw to adjust idle, all is good.</TD></TR></TABLE>

Happened to me. IIRC, a Z6 motor is adjusted as thus: with IACV disconnected/closed, idle is usually 400rpm. Hooked up (and I believe idle screw full in), it's at 700rpm. Then use the screw to increase idle.

Best way to tell is to remove the air filter/tube and plug one of the two holes inside the TB with your finger. If it still does it, try the other, then both. Normally the suring will stop and idle will drop very low if you plug the IACV hole.