91 1.5 Idle Surging.code 10

I Just Bought A 91 Civic 1.5. The Vehicle At Idle Surges Up And
Down.i Pulled Off My Iacv And Cleaned It And Did Not Work.so
I Replaced It With One Off Of My Buddys Car.same Problem.my
Check Engine Light Is Not On But The Ecu Is Flashing Code 10 For The Iat.please Help With Any Info.

did you reset the code and see if it comes back ?

if you have a dpfi, the iat is the little white plastic thing right next to the iacv. its on one of the runners

Could The Iat Sensor Make This Thing Idle The Way It Is?
I Havent Tried Reseting The Code.i Disconnected The Battery
And Reconnected It After I Changed The Iacv.i Was Told It
Had To Be Driven Quite A Bit To Let The Pcm Relearn The Idle
But Ive Put About 100 Miles On It.does Anyone Know The
Correct Procedure To Test The Iacv And Iat Sensors?

well the idle up and down strangly seems like when my distributor was going out it did a timign advance and retard alot before it went.

does the surging only happen at cold start up or all the time ?

happens as soon as vehicle is started.last night i rechecked it and now
there is a 10 and 14 code.if it is stone cold it will idle normal for about
10 seconds.

if you iat is bad it could be telling the ecu the wrong air temp which could result in your surging

the iat needs to be tested at room temp, around 70 degrees. you need to measure resistance on the to terminals coming out of the iat they should be around 1-4 ohms. I'm having this same problem on my 88 1.5 and I can't seem to figure it out. I replaced the eacv last night and the car ran fine for awhile then I shut it off and about an hour later restarted and it started surging again. I can unplug the eacv and the idle will go down to normal, does yours do this also?

curt, sounds like either you got a vacuum leak or your iacv is bad. usually unplugging fixing idle is a bad iacv

I'm pretty sure it's not a vacuum leak I have changed all the hoses. As far as iacv I put another one on today (used) and the car ran find until I turned on the air conditioning and then the high idle came back. The idle will drop to normall again if I unplugg the iacv. Does the iacv boost the idle for bigger loads? like a/c, lights... The new iacv I installed was off a car the was running fine but it didn't have a/c


Curt

your idle always goes alittle higher when running your ac, now idk how high yours went but with ac running your idle is going to be higher

it goes up to about 2500 with a/c on, then when I turn off a/c the idle stays high.

how high is the idle with the ac off ?

that depends sometimes it a surging idle I would say between 800 to probably 1500. Or sometimes it justs jumps up to around 2000. But if its is idling fine around 800 and I push the a/c I can get it to jump up but not always.

my car had the exact same problem and i thought it was the throttle position sensor, i unplugged it and it ran fine..... plugged it back in and i fixed the real problem(a leak in my intake hose clamps)

anyone know why my 1.5 is surging only when hot ?
and drops when I stick my foot under gas and lift it.
thanks