jmansour

Ok I know this is over killed topic, I read all the others and I read the sticky saying read all this before you post but I'm at that point where asking is the only thing left.

So I bought a 02 civic with a eng light. read P0420 Cat flow insuff. bank 1.
I also noticed the car pulls you away when your trying to brake and when you put it in park or neutral the revs go up then get kicked down after a few (IACV kicking in)

I'm familiar with the whole IACV problem so I replaced the 02 sensor because that issue can cause high idle, lightly wiped the butterfly valve with cleaner and a rag, and cleaned the IACV. Looked for any air leaks as i put it all together and reset the idle.

Pulled the fuse, waited a minute, installed it. Held it at 3k rpm with my hand (under the hood) while monitoring the scan tool and then let off when the fans came on. timed 5 minutes not including fan time and then shut it off and went for a drive.

1 mile later the engine light came on again but this time for p0505 and p1505
I know its too early for the cat code to come back but still. It's a new problem. But now the idle actually hangs high as heck like 1500 or so after i hit the gas and let off. aka it's worse.

Upon inspection I also came to find out the screws on the airbox are all stripped except for the center one and one other. This shouldnt have any affect on running lean right? The MAF is after that point anyways?

So what else could it be. My coolant level is fine. My IACV is now clean, there are no leaks, and the butterfly is clean. I reset the idle.

Thanks and sorry again for adding to the idle threads

jmansour

reset idle 3 times

kinakoes2

Sounds like if you have an air leak in the airbox, plus you cleaned the IACV (which on other brands IME anyway, don't respond well to being cleaned)... looks like you need to fix the stripped screw issue causing an air leak, but first, replace the IACV instead of clean it.

What happens is the friction and vibration wear down the plastic valve element in the valve over time, and carbon fills in the gaps, allowing it to work a little while longer. Clean it, and the carbon melts away, making it an air leak (which is reflected in your high idle). Depending on what you cleaned it with, the solvent may also harm the plastic (esp if a strong one like carb cleaner).

Unless the vets disagree, I'd start with replacing the IACV after clearing the codes, then fixing your airbox screw issue. Once those are right, THEN do an idle learn... see if that works.

ezone

I think the IAC is probably stuck open now.


Engine still warmed up? Good.
Pull the breather lid off and plug the passage in the side of the throttle body with your finger. The engine speed should drop to almost nothing or die. That proves the IAC is the cause of the high speed.

Start it up again.
Get it idling, tap on the IAC and see if the speed starts dropping.

Tap on the IAC valve with something like the handle of a screwdriver.


IF tapping brings the idle speed down then either clean the IAC or replace.

(The exact same goo that builds up around the throttle blade collects in the IAC and makes it stick. You disturbed the goo by cleaning.)
Clean it some more, make sure the rotary valve is freed up. It might take a few tries at cleaning it.
At work we replace them.....but for friends I have cleaned them.


AFTER you fix the high idle speed issue, THEN you need to do the idle learn again.
----

The air filter housing can't cause the problem. It might be a problem, but it's not causing the fast idle.
There is no MAF on that car.
And it probably needs a cat for the P0420 code..


HTH

jmansour

The IACV got unstuck because it works now. it kicks it back down. I did the relearn multiple times (over three). I retapped the o2 sensor hole and replaced the sensor. drove it some more and the cat code came back. Idk if its kicking on because of lean conditions.

ezone

Cat code usually means it needs a cat.