92 Civic Idle Problem

Mikes92Civic

New Member
I have a 1992 Civic Vtec SOHC 1.6l with air that just started acting up a few days ago. On start-up the car runs fine opening at about 1100 RPM then settles down to about 800 after a couple minutes where it will stay until the car gets hot (about 15 minutes). Once hot the idle will reduce to just above stall at about 400 RPM. There is no fluctuation in the idle, acceleration is fine but the idle drops lower the hotter the car gets but bottoms out at about 400 RPM every time I come to a stop. The car shakes heavily when the RPM drops below 700 RPM and this problem is consistent, it happens each time I take the car out. The car has not come to a stall yet but it does get close but only when hot.

Any suggestions would be most welcome.
 

HeX

Authoritah, respected.
Staff member
Registered VIP
5+ Year Member
10+ Year Member
Try cleaning out the Idle Air Control Valve with carb cleaner. If I'm not mistaken, a clogged IACV can cause your issues. Try that first.
 


Mikes92Civic

New Member
I cleaned the air idle cv but it made the situation worse. Now the idle drops almost to a stall even in a cold start. I guess this means a new cv?
 

SpeedTechnik

Nothing but Performance
Registered VIP
First lets start with a proper diagnosis. Lets not dail in and point to the iacv as the culprit. Do you have any cell codes? How long has it been having this inconsistent idle? How was it before it happened? Has anything changed during? What have you tried doing to fix?
 


Mikes92Civic

New Member
I cleaned the IACV a few days ago, didn't make a difference. The problem has been happening 2 weeks or so, prior too ran nice and smooth idling at 700 rpm consistently on stop. There are no codes but the problem repeats consistently. On cold start the car runs fine but when the car gets to operating temp the idle drops to about 300 rpm and rough every time you come to a stop, the car seems to be using more fuel now as well. Tonight I swapped out the IACV with another one and exact same problem no difference.

I noticed when I run the air conditioning the idle goes back to normal. If I leave the air running, when I bring the car to a stop the idle will drop and bounce back up to normal.
 
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