- Apr 18, 2006
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Well, if you start having idling problems, one of the possible problems is the IACV. Usually this is the easiest to do, so I start with this first, if this fails, then it's checking the intake vac lines for leaks (various methods to do this, but depending on method, it simply shows if you have a leak or not, not where.)
In my case, idle was 'sometimes' rough, so I took the time to do it today, and decided to do a DIY writeup about it.
What the IACV does is regulate the air coming into the intake when idle, hence the name. Honda manuals call it the EACV, since it's electronically controlled, but I know it as IACV, because Intake Air Control Valve is something I can recall, while I have no idea what EACV is a shortform for.
First things first, identifying where it sits. Two 12mm bolts hold it to the intake. Take those out AFTER you remove the plug.
First, I remove the plug (the green one, it's a plug with clips so remember to press the tab before removal). Then I removed the two 12mm bolts.
You have to clean the two holes only, and the two holes on the intake.
You can use an intake/carb cleaner to do that.
but since I felt like taking it out, I did.
Those are the two IACV holes, they are usually caked with oil residue and dirt (if your filter not filtering properly, this is where some of the dirt/sediments ends up. The oil vapour comes from the breather hose from the valve cover, so that's why running an oil catch tank helps to reduce this maintainance somewhat.
I removed the two coolant lines, and the two bolts that hold the IACV. make great plugs to prevent more of your coolant leaking out. I forgot to take pictures of those, so use your imagination.
With it removed, this is how it looks like.
I cleaned up the holes of the IACV port on the intake and IACV, and this is how dirty is was. I also changed the dual o-rings, but they were actually quite okay in the first place, and is reusable, but I don't take this out everyday, so might as well do it right now. I put some RTV sealant, but that's not really necessary.. just something I do for better seal.
Well, 100,000km of travel would probably be a good indication of how it got that way, not to mention I do not use a oil catch tank, so oil vapour from the valve cover goes through the breather pipe and gets piped back into the intake. Over time, it will clog, so then you start to get idling issues, like too low an idle. That's why this is first, before everything else, because this is a usual cause of idling issues.
Though not really necessary, but I also tested the circuit of the IACV to see if it's healthy, and from the readings, it checks out okay, so no problems there. but the high reading shows it's age, as it gets older, connections will deteriorate, and when it gets more than 15ohms, it's time for replacement. Either that, or ditch it completely (means your ECU will not correct idling speed based on electrical, powersteering and a/c load, so if you own a race car without those.. why run an IACV?) but you need a standalone to be able to turnoff an IACV error code so it runs proper. (Hondata has that, Crome, I dunno, I think probably yes.)
Install them back the way you took them out, and check all fittings and hoses to see that they are tight if you removed any. Start the engine, and your car should idle fine from cold-idle to warm-idle.
Assuming that the source of idling issues is the IACV, you won't need to fiddle around with the idle screw. But slight adjustment maybe necessary. I didn't do it because I need to remove the filter pipe to do it. Kind of simple, if you worked with motorcycle carbs before, you'd know this by heart.
I'll add this part with photoes when I actually remove the filter pipe or something, for now, it will end here.
If it doesn't idle fine, and your idle cycles, it's time to check the vacuum lines for air leaks, which takes quite a bit of time. Sometimes the vacuum leak can come from the intake gasket, but that's of a very low probability. That's why vacuum leak test comes second. It's takes a lot of time to pinpoint. To identify that the leak exists is easy, to find where is the time-consuming part.
For those that enjoy getting your hands dirty.. happy working on your cars.
For those that don't, now you know what your mech does when he first troubleshoots idling issues.
Well, although I know how to do it, I'd rather pay the mechanic actually.. my hands are too big to remove it without sustaining some scratches and cuts. LOL!
In my case, idle was 'sometimes' rough, so I took the time to do it today, and decided to do a DIY writeup about it.
What the IACV does is regulate the air coming into the intake when idle, hence the name. Honda manuals call it the EACV, since it's electronically controlled, but I know it as IACV, because Intake Air Control Valve is something I can recall, while I have no idea what EACV is a shortform for.
First things first, identifying where it sits. Two 12mm bolts hold it to the intake. Take those out AFTER you remove the plug.
First, I remove the plug (the green one, it's a plug with clips so remember to press the tab before removal). Then I removed the two 12mm bolts.
This is the picture of the IACV with the coolant lines still connected.I removed the brake vacuum line for easier access to remove the IACV, but please REMEMBER to put them back.. THIS IS YOUR BRAKES.. expect lousy braking performance (to the point of it being dangerous) if this hose leaks or you forget to put them back.
Then again, your idle should be way off when you start your car with this disconnected, so if you actually hit a tree because you forgot to put this back on, and ignored the way the engine was idling, you should probably leave ALL work to a mechanic.
You have to clean the two holes only, and the two holes on the intake.
You can use an intake/carb cleaner to do that.
but since I felt like taking it out, I did.
Those are the two IACV holes, they are usually caked with oil residue and dirt (if your filter not filtering properly, this is where some of the dirt/sediments ends up. The oil vapour comes from the breather hose from the valve cover, so that's why running an oil catch tank helps to reduce this maintainance somewhat.
I removed the two coolant lines, and the two bolts that hold the IACV. make great plugs to prevent more of your coolant leaking out. I forgot to take pictures of those, so use your imagination.
With it removed, this is how it looks like.
I cleaned up the holes of the IACV port on the intake and IACV, and this is how dirty is was. I also changed the dual o-rings, but they were actually quite okay in the first place, and is reusable, but I don't take this out everyday, so might as well do it right now. I put some RTV sealant, but that's not really necessary.. just something I do for better seal.
Well, 100,000km of travel would probably be a good indication of how it got that way, not to mention I do not use a oil catch tank, so oil vapour from the valve cover goes through the breather pipe and gets piped back into the intake. Over time, it will clog, so then you start to get idling issues, like too low an idle. That's why this is first, before everything else, because this is a usual cause of idling issues.
Though not really necessary, but I also tested the circuit of the IACV to see if it's healthy, and from the readings, it checks out okay, so no problems there. but the high reading shows it's age, as it gets older, connections will deteriorate, and when it gets more than 15ohms, it's time for replacement. Either that, or ditch it completely (means your ECU will not correct idling speed based on electrical, powersteering and a/c load, so if you own a race car without those.. why run an IACV?) but you need a standalone to be able to turnoff an IACV error code so it runs proper. (Hondata has that, Crome, I dunno, I think probably yes.)
Install them back the way you took them out, and check all fittings and hoses to see that they are tight if you removed any. Start the engine, and your car should idle fine from cold-idle to warm-idle.
Assuming that the source of idling issues is the IACV, you won't need to fiddle around with the idle screw. But slight adjustment maybe necessary. I didn't do it because I need to remove the filter pipe to do it. Kind of simple, if you worked with motorcycle carbs before, you'd know this by heart.
I'll add this part with photoes when I actually remove the filter pipe or something, for now, it will end here.
If it doesn't idle fine, and your idle cycles, it's time to check the vacuum lines for air leaks, which takes quite a bit of time. Sometimes the vacuum leak can come from the intake gasket, but that's of a very low probability. That's why vacuum leak test comes second. It's takes a lot of time to pinpoint. To identify that the leak exists is easy, to find where is the time-consuming part.
For those that enjoy getting your hands dirty.. happy working on your cars.
For those that don't, now you know what your mech does when he first troubleshoots idling issues.
Well, although I know how to do it, I'd rather pay the mechanic actually.. my hands are too big to remove it without sustaining some scratches and cuts. LOL!
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