97_white_civic

Hello, New here. I have done the research as far as getting the Iacv malfunction code but I'm stumped now. I have a 97 civic- with d16y8 engine. I went to remove the IACV and noticed there is only one hose connected? Can anyone point me to a diagram or something that shows where the hoses that connect to the IACV connect. There was no coolant in the one line that was connected to the IACV.
Thank you

ezone

So am I. Got a real code number?
Got a pic of your IAC valve?
And the hose you speak of?
Manual trans or automatic?
DX/LX/EX or what? Coupe/Hatch/Sedan?

97_white_civic

Manual Trans
It's an EX Coupe
Code I am getting is p0505
I can take a picture tomorrow. If it helps, the one hose that is connected goes into the Throttle body. The IAC valve has the two ports for two hoses, but only one hose was connected and the other is no where to be found.

ezone

Ok here's a parts diagram pic of water hoses and IAC (if I picked the right version car)




How can it be missing one of the hoses? LOL
Has the engine or car been ******?

97_white_civic

I was ripped off pretty hard by the person that sold it to me. They removed the check engine light <which I realize I should have been smart enough to check> but now I have a car with about 3 or 4 different engine codes that I have to work through and it appears he fixed the car up just enough to get it running decently

97_white_civic

Here is where I am at currently, There's the IAC valve. Also, picture for reference that there is only one hose there. That is the hose that connects to the bottom of the throttle body.

ezone

If the IAC is not connected to water, then there has to be other issues too.

You probably need to see where the rest of the hoses went and what's still hooked up, bypassed and not connected.

Hoses # 1,2,5,6 in the parts diagram are all part of one complete coolant circuit IIRC. Crankcase vent tubes, throttle body, and IAC are supposed to all be plumbed 'in a line'IIRC

Correcting the coolant flow may not resolve the code though.


HTH

97_white_civic

Thanks, guess I'm going to need to do some digging and figure out what the heck is going on in there.

97_white_civic

The weather here the past two days has been crappy so I've only had a moment to peak under the hood to see if I can figure out what's going on. It appears that they took hose 6 and connected it where hose 2 should be connected. <crappy paint diagram for visual>...With that configuration, they appeared to have eliminated IAC valve.

ezone

So it would seem the throttle body and IAC are no longer receiving hot antifreeze circulation?

Might lead to icing-- and low idle RPM if it did ice up. Maybe sticking too. IDK.

What idle problem is causing the P0505? High or low idle RPM?

97_white_civic

I sorted that problem out I believe. It appears hose 2 went to where hose 6 should have been connected and hose 6 was the missing hose. Rerouted hose to back to the IAC valve and added hose 6. Ran the car up to operating temp and could feel the IAC valve was hot <assuming from finally having liquid running through it> Car is idling high right now at about 1500 rpm. Took off the positive battery cable and I am going to try after a little to see if the computer relearns proper idle speed. I'll update after I do the relearn process.
Thank you a ton for the help you've provided so far!

ezone

It won't learn, because you have a real issue there.
You need to figure out why the idle is too high after warmup.

Does it surge repeatedly?

97_white_civic

No surging. Just starts up and seems to stay right at 1500.

ezone

Pull the breather tube off and plug the open holes in the sides of the throttle body (use your fingers), see if the idle speed comes down to normal or way below. (warmed up engine)

Note which port brings the speed down.


If not, I'd be looking for vacuum leaks such as the cruise vac hose fell off.

97_white_civic

Scratch that, surging is happening now. I imagine the process you just mentioned still applies.

ezone

Yes.

97_white_civic

Plugging the port that goes to the IAC valve brings the engine down to normal. I have a feeling I should probably just order a new IAC valve since it was by passed for <who knows> how ever long.

ezone

Tap on it, see if the idle starts to come down. Could just be stuck inside.

old97civic

LOL doesn't it always come down to banging on things with a mallet?

ezone

Expertise is knowing WHERE to hit it with the hammer and how hard to hit.


And....size matters!
You don't want to bend, break, or damage anything.

97_white_civic

Put new IAC valve on, still revving up and down. Could the Coolant level be the cause of this surging? Not enough coolant for the system? I did try tapping on it with a screwdriver handle and a mallet before getting the new IAC valve. Didn't change, so went ahead with new IAC valve and still, no change.

97_white_civic

Update* found the damn vacuum line that was off. Was the one from the cruise control. Car starts up cold idles around 1.5-2k then drops to 1k. stays around 900-1k at running temp. When I first step on the gas and let off the idle jumps minimally then returns to 900-1k. Only engine code I now have is p0141 (o2 sensor). So, I'm not sure what this means at this point...

ezone

Pretty sure I mentioned that one earlier!

Rear O2 sensor heater circuit.

Is that the only code?
If it is the only code....First I'd check the rear sensor itself, ohm the wires for the heater...Spec says 10-40 ohms.

97_white_civic

Yes you did. Still having issues with is doing random idle surging. Thought it was nailed down, but anytime I give it some gas and let off it goes through about 2 mins of surging and settles back at 1k, but no other code than the o2 sensor.

ezone

Is it surging repeatedly between 2000 and 1200 rpm?

Idle spec is like 700ish at operating temperature.

97_white_civic

Yes, It surges between 1200 and 2000. Maybe another small vacuum leak somewhere?

ezone

That would be a pretty large vacuum leak. I thought you had it idling at like 900 or something?

Plugging the open ports in the throttle body again, does plugging the passage to the IAC get it to idle down again?
Put the original IAC back on and retry now that the cruise vacuum hose is fixed?

Check inside the control unit for leaking capacitors or burn marks?

97_white_civic

I'm at a loss with this car, the idle fluctuation is so sporadic. Sometimes it's between 1k-1.2k if I step on the gas to rev it, it will jump around from 1k-2k. then settle after around 25 or 30 seconds. I checked all my vacuum lines they are all attached. If I get the car warm and let it idle around 1k and plug the port in the TB the car sputters and dies. New IAC valve gets hot, so I assume it's working. I do think the car has a blown head gasket...but I'm not sure. If I start the car with the radiator cap off, fluid will shoot out of the radiator about 5 feet in the air. Then when it's idling there are tons of bubbles in the coolant. Sound like a blown head gasket?

ezone

Ooouch that's a geyser! Yes it sounds like something a blown head gasket would do..
Coolant level should stay steady.... and you sound like you have cylinder pressure leakage forcing liquid to come out of the radiator.

Spurlin96

I have the idles issue but I plugged the bottom hole in the throttle body and the idle goes down... what does that mean??