Idle problems with 89 Civic

The Car: 1989 Civic LX with 1.5 Liter

The Problem: Idle surges and drops to >400 rpm and occaisionally causes the car to stall. The problem seems to be worse when in gear (AT Tranny) and also is worse when multiple electrical items are on. Under acceleration the motor is strong and has no problems.

So far I've replaced the main relay (yes I was having the hot start issue) and the cap and rotor. Spark plugs are correctly gapped and appear to be correct color, not burnt, not oily. The tranny fluid is full but looks a little burnt.

Any ideas?
:confused:

i used to have the same problem and like once a month or so i still do, its usually after i drive it for a bit then let it idle, mines std though and has never stalled, try checking all ur filters, feul and air. and try this: when it does it just rev the car and then let it idle again and see what happens.good luck. i still cant figure it out, but since mine dosnt stall i dont worry bout it much

check all of the vacuum hoses around the inlet and like fiercecivic said maybe change the fuel and air filter,

Had a similar issue with a Mustang a couple of years back. It ended up being EGR related. I replace the EGR and EGR position sensor and it went away. Are you getting any check engine lights coming on?

EGR or the IAC

EGR or the IAC
what r these?

EGR-Exhaust Gas Recirculation

IAC-Idle Air Control

jmk_98513, have u checked ur ecu for a code? Mine stsrted doing it again last night and when i checked it i had a code 16. BTW does anyone know anything about feul injectors? Because thats what code 16 is. Anyways check ur ecu

I have that same problem to. But only when the car warms up. It will idle to 1500 then drop and after I drive for a while and it gets hot. The idle will drop and kinda stumble then I get some code 4. But I just turn off the motor and start it up again and it goes away. But it comes back after a while. Some bolts were loose on the dist. but I tightend them back up and it hasn't thrown that code 4 anymore but its stills idles wierd. I checked all the vaccum lines and everything. Wonder why it does that.:confused:

I will check (and replace if necessary) the EGR.

Noticed something today in stop and go freeway traffic, whch I don't normally get caught in. The idle problem almost always shows up right when I first come to a stop and the AT tranny is downshifting, but today in the stop and go, I used the gear selector to force it down to D2 before coming to a stop and did not have the idle issue. Is there a electronic or vacuum operated sensor on the AT that could cause this?

BTW: Thanks for all the responses.

Jim "I want a B18 in my 89 Civic" Kelly :)