91 1.5 Idle Surging.code 10

[jcl27]

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.

[civickiller]

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

[jcl27]

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?

[maxassassin]

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.

[civickiller]

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

[jcl27]

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.

[civickiller]

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

[curt_h]

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?

[civickiller]

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

[curt_h]

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

[civickiller]

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

[curt_h]

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

[civickiller]

how high is the idle with the ac off ?

[curt_h]

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.

[civicluva2001]

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)