Okay so the title almost sums it up as much as I can but I recently just purchased a new civic. While it was fine for the first 2 months around month 3 an issue came to. I was sitting at a stoplight and noticed after a few minutes my idle jumped up to 1100, When I gave it gas while still on the clutch in order to take off I noticed a hiccup at around 1400. I pulled over and in neutral put my foot on the accelerator and it would bounce between 1400-1900 repeatedly getting slower as i give more gas until i finally give it enough throttle to basically push through. I figured it was an iacv issue, and today my new denso replacement iacv came in, when i took off my throttle body to replace my iacv i noticed that the iacv was built into this throttle body. My engine is a d16y7 and i have a feeling the throttle body could be aftermarket although im not too sure. I cleaned the throttle plate as much as i could put everything back together and my issue is still there. However when i turn my car off and back on it’ll go away until im stopped again for a long enough time. I’m completely perplexed and have no clue what’s going on. If this helps it also throws code po505 when the issue happens. When i measure the resistance on the 2 outer pins of the iacv it measure 5.3 ohms

 

Somebody help please 🙏

 

Post a photo of your IACV. Does the bottom of your throttle body have a 3-wire grey plug connected to it ? The fact that this "comes and goes" might suggest that the IACV is fine and you actually have an air bubble in the cooling system... you would have to fully bleed the cooling system to verify that this is the culprit. If it was, your problem will go away after bleeding. If not, lets look back at the IACV.

 

Will do the second I get out of school! I have found out though that it doesn't seem to be intermittent but also has a specific scenario when it starts. It usually comes about when I'm sitting stationary. ie at a stoplight. My idle will be fine then in about 3-4 minutes of me sitting the idle jumps ups to 1300 and when I press the accelerator my idle starts to bounce like I described before, until I give it enough gas to almost push past the hiccup point. As well as while I'm driving when I let off the throttle it jerks and when I let back on it jerks again. What necessarily doesn't make sense to me is that when I turn off my car and turn it back on it fixes it immediately. My iacv is a 3 wire connector but my iacv seems to be built into my throttle body? I took it off in order to replace it to hopefully fix the issue but I don't think I would be able to without just purchasing an entirely new throttle body.

 

Replacing the IACV doesn't mean you have to replace the throttle body on a d16y7. They are separate parts. If you want to replace the IACV, you'll have to take the throttle body off to get to it. This means you'll need to replace the throttle body gasket while you're at it. Scrapping the old one can be tricky. I recommend using "plastic" razors. You can pick them up at ace. Scrub daddies also work. Neither will mar the surface, unlike metal tools.

 

Yes, but for some reason mine really is built into the throttle body?? i’m really not sure if it’s an aftermarket tb or something of the sort. i have a new iacv as well as tb gasket but when i removed my throttle body i found out that it was indeed built in.

 

this might help: https://www.instructables.com/Replac...control-valve/ tell us if it looks like that. Better yet; take a photo of yours and post it here.

 

this is a picture of my iacv (it’s kind of a bad angle since my tb is still on)

this is a picture of my tb itself honestly not sure whether it’s a y7 or y8

i’m not too versed in hondas and trying to expand my knowledge. any help would be greatly appreciated as i still haven’t found the problem ive been chasing.

 

No it does not look like that. i just posted pictures on how it looks too if that helps

 

That is a d16y8 manual. The part in the center focus of your pictures is the throttle body position sensor (TPS), not the IACV. The IACV is attached to the manifold, near the throttle body. Lucky, for you, it's easier to get to. Look up "d16y8 manual replace/clean iacv" for more details. Some of what I said about the d16y7 doesn't apply ( like the throttle body needing to be taken off). Post here if you need more help. AND keep us updated!

 

thank so much!! i found the iacv i will be cleaning it tomorrow. i’m currently at walmart and i unplugged my iacv and get the idle issue i was describing (bouncing when im very slightly pressing the throttle) i feel like this even more pinpoints it to being my iacv no?

 

It's not the only possibility. It's just the most probable possibility. It could be the MAP sensor, the PCV, the surge valve, an electrical fault, or any mix of these. If it only misbehaves when your foot is off the gas, then the IACV is even more likely to be the culprit. I accept thanks in the form of " likes" in the forum posts.

 

This is my iacv. honestly doesn’t look dirty at all. Now i’m kind of stumped. Although it doesn’t have any branding meaning maybe aftermarket?? could be failing due to that

 

Sometimes there's gunk inside the passageway. Clean it out with throttle body spray. Additionally, your problem might be a vacuum leak. Check for vacuum leaks by spraying throttle body spray near the hose inlets for the vacuum lines. You can tell which lines are part of the vacuum system by the fact that they are attached to the intake manifold. If it's not a vacuum leak, and cleaning that IACV doesn't help, i'd put my money on the purge valve. The purge valve will fight the IACV for control over idle during operation, resulting in hunting idle. You can test the purge valve by taking it out and blowing into it. If your breath goes through to the other side, it means it's faulty.

 

Okay i did clean it out anyways and after letting it dry i put everything back together. so far so good, my surge on every start before it settles went away. i just disconnected my battery waiting for my engine light to reset then im going to take it up the road and come back and let it idle to see if my issue comes back

 

Okay bad news issue is back, but now all the surging and other stuff is gone. my only issue is now after sitting idle for a few mins my idle jumps up by 2-300 remains steady and when i subtly put my foot on the accelerator it bounces between 1400-1800

 

Here are the next most probable things. Vacuum leak, purge valve and/or canister, grounding wires ( there are 3- battery, transmission, engine- https://www.ebay.com/itm/27717031856...Bk9SR-To1trKZg OR https://www.ebay.com/itm/38404904578...Bk9SR-bo1trKZg).

 

okay well new update, i took the throttle body off again just to see if the throttle plate was sticking and cleaned it with carb cleaner. i realized that it doesn’t even look like there’s a gasket on it at all. also i found out my idle issue only happens once my car is warm. i can sit and wait for it to warm up with no issues at all but once it reaches operating temp is when the issue happens. could this be my culprit and if so what tb gasket do i need? i know there a few different types depending on the tb’s.

 

There appears to be a T/B gasket in the photo at the top of the thread... if it is no longer present, then purchase one for a D16Y8.

 

Check the evap purge valve. I talked about how to do it, in a previous post. You can use hose pinch pliers to check it quickly, without unplugging anything.

Dealing with the hoses for the purge valve may prove troublesome. The hose clamps like to slip when taking them off. You may need hose clamp pliers to get them off easily.

AND if you're taking the hoses off the purge valve, these may be handy.

 

Out of interest, what is the ambient temperature where you are? This idle bounce is happening when the ECU has not relearned idle values properly (you did disconnect battery and reset it). For the idle relearning procedure to start, the inlet temperature must be over 53 or 54 Celsius. If it is coldish outside, it might not be easy to achieve. To be sure: start her up and let it idle with the bonnet down (to capture as much heat as possible within the engine bay). After the fan kicks in, let it idle for at least 3 cycles of fan kicking in and out and then it should settle down on proper idle value and the bounce sould stop

 

it is usually around 60 degrees this time of year, some days hotter than others. so i should just let my car idle for a while to see if that fixes it?

 

do you mind linking that post? i can’t seem to find it

 

Yes, try that, nothing to lose there and it should be done. But I would bet you have a vacuum leak somewhere