Mario245

Well I had unplugged the IACV one night and accidentally plugged it back in while the car was still running and there was a loud noise. The car started surging pretty fast so I shut it off. Now whenever it idles its really low and slight sputtering can be heard from the exhaust.

The car drives fine and this only happens at idle, and the car ran perfectly before I did this. Could this have screwed up the IACV somehow?

Former User

Where did the loud noise come from? The IACV? The ECU?

Mario245

Well it sounded close to me so I'd say from around the IACV.

Former User

Is the CEL ON?

If you now unplug the IACV connector while the hot engine is idling, does the idle speed change or stay the same? If there's no change then you likley need to replace the IACV.

Mario245

No light, let me go warm up the car and see what happens when I unplug the connector.

Former User

By the way, what year/engine Civic? I should have mentioned that you should also carefully inspect the IACV wires and connector for damage or burning because another possibility is that, if the idle speed does not change when the IACV connector is unplugged, an IACV wire is broken or has a short.

Mario245

It's a 1998 EX with a JDM B16a swap, the previous owner was a good friend and he pretty much babied it, he even made sure to change oil and spark plugs before selling it to me.

Mario245

Well I just unplugged the connector and the rpms dropped alot and it sounded like it was struggling to stay started. Another thing is yesterday it was a bit warm outside and the car stalled on me twice when I was parked, but it started back up right away.

Mario245

Bump, this is my daily so I really need to fix this.

Former User

Hmmm. The outcome of this test suggests that the IACV is working at least partially. You should check for a bad wire running between the IACV and ECU or bad voltage to and from the IACV.

nengun-nuub

i would check all the wiring around the intake. such as your iat, map sensor, iacv, tps sensor. make sure they are all connected and the wiring is good. also make sure the connectors are plugged into the right sensor. some of the conectors will work on more then one sensor. this doesnt sound like your problem, but i would also make sure the your manifold bolts are tight, same with the throttle body. just to make sure you dont have a manifold leak. with swaps somtimes abnormal things happen so check everything.

Mario245

How would I do this? I'm not very good with the whole wiring thing sadly.

callmechad

mario, your in good hands ron will guide u in the right direction. he did me :D. as for the wiring part im not sure on how to.

Mario245

Bump again, after plugging it back in I never reset the ECU, would this have caused any problems as well?

Former User

It's worth a try.

Mario245

Now if the previous owner had it tuned, would resetting it erase the tune? Sorry for all the questions, this is my first swap and all. Also would a video of the sound I'm talking about help you out in figuring out what is wrong?

Former User

Resetting the ECU should not erase the tune.

Based on the information you have provided, you are having a problem with the IACV circuit. This could be a damaged IACV, IACV wires, or ECU. For the wires, use a multimeter to test for continuity and for a short in the Yel/Blk wire running between the main relay and IACV and the Blu/Blk wire running between the IACV and ECU. If the wires are fine, then you may need to try swapping your ECU and IACV with known good ones. Maybe you have a friend with a similar Civic?

Mario245

I moved to a different state after buying the car so I don't know anyone. I'll look into buying a multimeter and check those wires out asap.


EDIT: Actually, looking at the tools I have, I noticed a auto circuit tester. A sort of pen type thing. would that work?

Mario245

Well I figured I'd try to atleast clean out the IACV see if that would help, It didn't.

I have a replacement coming sometime this week or early next week.

R.Storvick

might check the FITV as well, i know it has idle problems and can be a sneaky pain in the ***!

XKINGX

try setting your idle air speed. arm the engine up and then unplug the iacv. set your rpm to 450ish with the set screw on the throttle body. after u get it set to 450ish plug the iacv back in and u should help or stop the car from stalling when u come to a stop.

Mario245

I don't have a FITV, and the car usually idles around 1400-1600.

Mario245

Well I reset the ECU, let it idle for 10 minutes and it seems to be at a stable idle of about 1200.

But when I turn on my lights the idle drops to about 1000 and it sounds like its gonna shut off, before I reset the ECU the idle would rise then slowly come back down, is this because I need to drive it for a bit for it to fully learn everything?

Another thing is I believe I have 2 holes in the exhaust piping near the muffler, would this be causing the sputtering I hear?

EDIT: Forgot to add that it seems to vibrate a bit more now.

Mario245

Well I just got back from driving it after putting the new IACV on and it drove fine, no more shuddering. low idle, etc etc. It sits at about 1250 and stays there when idling.

I'm still guessing that sputtering it because of the hole in the exhaust pipe cause I see alot of water dripping out since it was cold here and I havent drove it for a bit.

Mario245

Alright, so I went and bought a multimeter, what settings should I use to check the wires?