Hey All, I have a 1992 Civic CX Hatch with a 1996 B18B1 swap and I have a bit of an odd idle, not even a problem, just observation I guess?

I've noticed that when you put the clutch in, or even sometimes randomly at stoplights, the idle will drop low and bounce back to where its supposed to be.

I typically acquaint this with a vac leak, or something else of that nature.

I have a vac line 'plugged' because my CX charcoal canister has a spare spot on it that the B18 doesn't use, anything else that would cause this?

ideas, things to check for?

I also bought a new toy today, Boost or spray, here I come :

 

bump

i would like to know about this as well because my buddies civic does this same thing, especially at start up and he just recently did the swap.

 

Bump, someone show me that honda-tech DOES have tech here people...

 

Could be a number of things from TPS out of wack, to idle screw needing adjusting. If its not effecting driving i would leave it. If you want to fix it because its a complete annoyance then start with those 2.

 

if it was the idle screw, wouldn't it ALWAYS be bouncing?

Its an on/off problem really, no rhyme or reason.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Dasfinc &raquo;</TD></TR><TR><TD CLASS="quote">if it was the idle screw, wouldn't it ALWAYS be bouncing?

Its an on/off problem really, no rhyme or reason.</TD></TR></TABLE>

Not always thats why i said it could be a number of things. Idle is effected by engine temp, amount of air traveling in, injectors, sparks, etc. The list can go on forever.

 

First thing to do would be to set your idle 1 1/2 turns out , then from there make your TPS is reading .45-.50v throttle fully closed. Disconnect your intake tube from your throttle body, with the engine at full operating temp ( fans have cycled ) place your finger over the port in the lower left corner of the throttle body, you should feel it sucking, but also note that if the IDLE drops when you place your finger over the hole, then you need to replace your Idle Air Control Thermal Valve located under the throttle body since it is leaking internally. I know the bouncing idle is normally associated with the IAC on the rear of the intake manifold but this is a quick check before dropping money on a IAC since we know they aint cheap.

 

my LS/vtec swap does the same thing too. im using an 96 LS block. i have this thing on top of the manifold blocked off too but one time i was cleaning my car and forgot to put that plug on the car ended up idling at 2000rpms. putting the plug on it drops back to normal.