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97 Civic LX, D16y7, 175k on car, ~6k on internals, stock y7 intake manifold

My idle has been very low lately, low to the point that the car feels rough, like it wants to die. I tried adjusting the idle screw, but even with it all the way up, I cant get it to even idle at 750 once the car is warm. When the car is cold, it idles high.

I'm going to clean out the IACV tomorrow see if it helps with the idle, but my main concern is, when the intake is off (open TB) there is a sucking noise coming from the passenger side hole in the TB (there is 1 hole in the front, and one on the side). I believe the front one goes to the IAVC, and the side one goes to maybe the TPS? Is this sound normal?

I singled out the noise by covering the holes.

PS- if I cover either hole the car does not die, but idle drops

Former User

Any CEL codes?

Does the low idle only happen with the A/C on?

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CEL code 65 for rear o2 sensor (I have a thread for this also, trying to get a o2 sim to work) other than that no.

This is a constant sound at idle. Goes away once I rev the engine (either that or the sound of the engine drounds it out) its been doing this for a while now, since before my a/c was even hooked up.

Former User

I'm not sure the sucking sound is abnormal. I would concetrate on the low idle speed when warm. Cleaning the IACV is a good place to start. Also check whether the PCV valve or hose is clogged.

Also check whether 7.5A dash fuse 15 is blown.

Here's the proper way to adjust the idle speed:

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I'll check that fuse tomorrow, but that is the process I used for adjusting the idle (someone showed me that here on my H-T n00b days =D) and after about 500-600rpm, the screw no longer has an effect, not like the 5 other honda's ive owned, where I could set my idle practically as high as I wanted with the screw.

Should I just try pinching the pcv hose to see if it makes a change?

As far as the "checked" recommended by that photo, i've replaced:
plugs (February)
wires (February)
dizzy cap (February)
dizzy rotor (February)
air filter (November)

Former User

You would pinch the PVC hose and listen for the click sound. If you hear it, the valve is likely fine.

You may want to pull the entire TB off and clean it and the IACV thoroughly. A replacement TB gasket only costs $2. Just remember to torque the nuts and bolts to spec, 16-lb-ft I believe.

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Roger, will do.

Maybe you can help in my o2 simulator thread? (few post down)

(thinking the CEL may be triggering other issues?)

Thanks!

Former User

The secondary O2 sensor has no other function than emissions, so that's not the cause of your problem. However, code 65 indicates that the heater element of the secondary O2 sensor is not working. That heater element and the alternator are on the same circuit protected by fuse 15. If fuse 15 blows, the alternator won't work. That could obviously affect the idle speed.

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Hmm, I HIGHLY doubt my alternator isn't working, as i'm sure my stereo system would have killed my battery a long time ago (especially since I was sitting in my car at idle earlier today for a good 45 minutes listening to volume almost max)

But once again, I will check, can't be too sure

Former User

You can troubleshoot code 65 pretty easily. If fuse 15 is fine, unplug the secondary O2 sensor and then check whether the the heater element power wire in the connector has battery voltage to body ground. If so, next measure resistance across the two black heater element wires for the sensor itself.

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Fuse 15 is good. I'll mess with the wires tonight