Hi, I have a 1989 Honda Civic dx I think, special edtion. 1.5L. Recently I swapped out motors because of high KM's and wanted some revived life lol. Previous to switching the motor I had a hunting idle about 900 rpm to 1600 rpm by ear up and down pretty fast.
Now heres where a lot of things get eliminated. The motor I pulled from another civic ran mint, only 100,000 km on it sounded lovely. When I put this in my car suddenly I have check engine light on throwing IACV bad but the thing is I know its good because I left the intake intact from the donor car which ran perfect and just put it in my car.

So here goes round three... I take it to honda DUH spend a couple hundred bucks for them to over it and tell me nothing I dont know. They tell me its IACV which I know its not so i leave pissed I more than likely know more than thier mechanics. (lol jks)

anyways I decide its ECU controlled and I go to the donor car which I know works and I take the ECU out and use it in mine.. nope still crap. Only thing I gained was power is restored instead of misfiring and lack of power.

One thing is noted hesitation in the first 3 inchs of the gas pedle untill a certian rpm it stutters. Im lost what coule it be FPR? Fuel pump? Vacumm canister? Vacum lines have been tested no leaks apperently. im SSSSOOO LOST HELP!!

sorry for long post but 2 mechanics one unoffical mechanic and a lot of research has not solved it im frustrated.

 

It could be the wiring that goes to the IACV or sometimes people commonly switch around that wiring with the connector for the IAT. I would check this out, look at a repair manual to get the proper voltage/resistance readings for the IACV.

 

This sounds like the problem I'm having but mine is the stock d16a6 with about 230K miles. Mine does it once the car gets to running temp, but its worse in cold weather. I'm still trying to figure out what it is, but mine also idles slightly rough when it idles normal. When its idling normal, try unplugging the vacuum line from the fuel pressure regulator and see if it does that funny idle hunt, mine does. If you figure n e thing out let me know. BTW mine sometimes will hesitate, mostly in 1st from a stop.

 

tb sensor
iacv
ficv or some **** like that
timing
idle adjustment

my b swap did the same thing, i finally got it fixed when i turboed it, and had crome to see exactly what was going on. i would check those sensors in that order set the timing and lastly mess with the idle setting.

 

tb sensor
iacv
ficv or some **** like that
timing
idle adjustment

my b swap did the same thing, i finally got it fixed when i turboed it, and had crome to see exactly what was going on. i would check those sensors in that order set the timing and lastly mess with the idle setting.