civNC00

Vehicle:
2000 Honda Civic
D16Y8 engine, EX (i think)

I've read many Google search results about my rough idle, including many linking to this forum, and I decided I should clean my throttle body and IACV. I did label connection with a sharpie, but, like a dummy, I forgot that the intake cleaner would wipe away my markings for determining which coolant hose goes where on the IACV. Can anyone point me to a resource describing which one goes where? I've got the manual, but I don't see any diagrams that show exactly which hose goes to which port. They all just show an "engine coolant" loop. Does this mean the order doesn't matter? If it's just measuring coolant temperature, it may not care which direction the coolant is flowing through the box. Not sure.

Pictures:
http://imgur.com/2z157vV
http://imgur.com/IpdzI2e

I tried to highlight the hoses and ports with colors and letters. I think hose A goes to port C and hose B goes to port D. That way they won't cross over each other near the ports. I also tried to show that hose A loops around behind the intake and B pops up from around the bypass hose. Am I correct?

Any help is appreciated!

Regards

ezone

If you didn't disturb them too much, they should naturally lay darn close to where they were before.



This may help

civNC00

Well, I was hoping that would be the case. Yes, this diagram helps. I should be able to route them now easily! Did that diagram come from the manual? If so, what page?

Thanks for the help!

Edit: actually, I just thought of something else. I read several places about relearning idle. Turns out I was searching for 2001 honda instructions instead of 2000 (I got my year model wrong). Will I still have to relearn the idle after hooking all this stuff back up?

civNC00

Well...

I got everything zipped back up. Started the car for the first time in 4 days. It started up and idled around 2000 rpm for a minute or two. Then it proceeded to go do a step pulse between ~ 1400 rpm and 2000 rpm back and forth continuously. I wasn't sure what was going on so I decided I'd jumper the OBD1 port and see what the CEL said:

71 (the old misfire code that caused all this headache in the first place)
14 IAC Valve (Idle Air Control) defective circuit or unplugged / defective sensor

The code 14 is new. I plugged in 3 electrical connectors when I put the throttle body + IACV back on: 1 to the IACV, 1 on top of the throttle body, and 1 on the side opposite the IACV. I'm assuming they're all keyed so I can't plug 'em in upside down. I'm going to go check them again, but has anyone else had this problem before? Maybe the IACV is just shot and I'm SOL...

Edit: I took a video of the tach while pulsing. Can't figure out how to host since imgur doesn't seem to do .mp4 files...

ezone

Pic was from an online parts catalog.


Surging is usually due to stuck open IAC or vacuum leaks....or the computer can't control the IAC (see the code)

civNC00

Does that mean my only option at this point is to replace the IACV?

ezone

Not unless it's bad IMO. Figure out why it set a code first. Wrong connector hooked to it? Plug not fully seated? Bent pins?

If the IAC is just stuck, I'd clean it and get the guts of it freed up and working/moving again.

civNC00

The manual says to check the resistance between two pins for 16 - 28 ohms. I'm assuming this is the resistance between the IACV female plug pins. I will take the throttle body back off today and try that.

I just got done cleaning the thing and now it gives me the code afterwards...

Here's a thought: I unbolted the IACV from the TB and sprayed cleaner down inside and scrubbed for a long time, but I didn't unscrew the plastic plug end because it seemed to have some sealant around the edges and I didn't think it would be good to disturb it. Should I have opened up the end too? Mine looks like this one:
http://www.oreillyauto.com/site/c/de...+control+valve

ezone

The terminals on the valve are male.
The terminals in the harness connector are female.

Problem: Your valve has three terminals, not two (right?)
Test resistance between pins 1 and 2,
then test resistance between pins 2 and 3.

If you measure between pins 1 and 3 you'd probably get 32-56 ohms.



What sort of cleaner did you use?
Why did you even take it all apart and clean it in the first place?
Was there a problem that necessitated this action?

civNC00

I checked the terminals on the valve itself. Yes, it has three terminals, not two. The resistance between 1&2 and 2&3 are both 20.3 ohms. The manual says it should be 16 to 28 ohms to be good.

I took the TB and IACV off the intake, took the IACV off the TB, cleaned both TB and IACV and IACV seal with throttle body cleaner and q-tips, then put it all back together with a new TB gasket. The IACV seal seemed to be in good shape. Then, I put it all back together, running into the coolant line problem in the OP.

I did this because I was getting cylinder misfire codes, causing low idle. It was not really an issue until recently it started stalling when I came to traffic lights - at speed everything functioned normally. Dirty TB/IACV seemed to be the most common solution:
https://www.civicforums.com/forums/3...e-posting.html
https://www.civicforums.com/forums/1...e-up-mods.html

I just got back inside from refitting everything and checking resistance and connections. As I said, the resistance measurement is in spec. I did notice something odd though. O'Reilly's part website showed the IACV I removed is for the automatic version of the car, but the car is a manual. This puzzled me, but not really bothered me. Today, I realized that it has BOTH on it. I'm guessing the old IACV quit, so the previous owner stuck the automatic version on there. That's what it's had for the 5 years I've had it. Never noticed until now. I can't imagine that would have a major impact on the problem I'm seeing now, as it's been working fine the past 5 years w/ the auto version. If I get a new one, I'll probably go with the manual version, but I have a hard time justifying getting a new one if the resistance is fine. Is it possible the IACV could be bad even with an in-spec resistance measure?

Pictures:
http://imgur.com/JVHbIsF
http://imgur.com/mZfwFlb
http://imgur.com/15R1W08

ezone

Misfire can cause low and rough idle, not the other way around.
A weak or dead cylinder should be relatively easy to figure out.
Misfire code should have been addressed first. (Looks like you were trying to do that, you just didn't pick the best way IMO)

Code 71= P0301 ??? misfire cylinder #1
Might be better if you use something that can give codes in the Pxxxx format.
----------------------------------

Kinda looks like you may have an intake manifold for a manual trans, and a throttle body for an automatic? ?? Will the wire connnector reach the other IAC valve? Nah....
If it's been working fine up until you messed with it, you need to get it back to the way it was before you messed with it.
Solve the code.
In theory, if you only moved the wires around at the throttle body, then the problem is PROBABLY right there.
Bad/broken/loose terminals inside the connector? Broken wires?

civNC00

I was experiencing low and rough idle, so I was searching through solutions to that. Those links point out a series of things to try and check/fix. Of all the things on the list, cleaning the TB and IACV were some of the easiest things for me to do, after replacing the plugs and wires.

I had been getting misfire codes on cylinder 1 and 2 and additionally the P-code for random misfires.

The car DOES have a manual trans. For some reason, the previous owner seems to have replaced the IACV (and I guess the TB as well) with the auto-trans version. I'm not sure how they did the wires to go from the 2 to 3 prong connector. Either way, I'm planning to stick with the auto-trans version for now since everything has been working fine until now.

I suppose the problem is likely with the wiring to the IACV. I blew the connectors out with compressed air earlier as well to try and clean them out. I will take it apart again tomorrow, but I have not followed the wiring away from the IACV before, so that'll be interesting.

The new code is: P1509 - Idle Air Control Valve System High RPM.

I think I did find something related to the misfire problem today though: I think my ignition coil was going bad and has been limping along. I was following other steps on those probable cause lists I linked earlier: checking the ICM and coil. The coil had a resistance out of spec, and when I started to remove it, I noticed the coil had a small crack on top. The ICM and wires checked out fine. I replaced the coil.

Pictures before coil replacement:
https://i.imgur.com/B4jSLr1.jpg
https://i.imgur.com/mEaRP6d.jpg

ezone

Oooh yeah that looks like a possible burn hole. There's another to the right near the other edge too.

ezone

Because the computer can't lower the idle speed. Still got the IAC circuit code too?

civNC00

Before, when I said I was getting the code, I meant I was getting a "14" code from the CEL. I looked up the CEL/OBD1 codes and read:

"14 IAC Valve (Idle Air Control) defective circuit or unplugged / defective sensor"

However, I thought maybe using an OBD2 code reader might give me a more accurate description of the codes (P-codes instead of 2-digits). There were 4 P-codes:

Random misfire
Misfire cyl 1
Misfire cyl 2
(don't have the list of codes in front of me but these were the results)

and
P1509 Honda - Idle Air Control Valve System High RPM

I interpreted P1509 from: http://engine-codes.com/p1509_honda.html
This site shows it as "P1509 IAC Valve Circuit Failure": http://honda-tech.com/showthread.php?t=1490107

I'm not sure which one I should be following. I'm also concerned now that, if the female connector is bad, it could be tricky to fix since someone has redone the wiring for the 3-prong IACV (non-native).

I'm going to pull it off again today and trace some wires. Maybe I should do a continuity test. I just don't know where the wires end up. Do they go straight from the female connector to the ECM? I'm still looking for a resource that labels the ECM pins for my year model.

ezone

I may have been asleep when I wrote that.
P1509 = A problem in the IAC circuit
P0505 = Idle control system malfunction
Both can render a code 14 when using the flashing CEL method. That's why I wondered what the "P code" is.
The P1509 is pretty specific in the definition, a circuit (electrical) problem.
The P0505 just means that the ECM/PCM can't control the idle speed for whatever reason.



Also, coolant flow through the IAC is important since the AT IAC incorporates the FICV for fast idle while the engine is cold.. If the valve can't get hot engine coolant (restricted or limited or nonexistent flow) then the fast idle speed doesn't come down at the right time. Low coolant, kinked hoses, plugged passages are all possible. You would need a good wiring diagram and/or service manual that covers this car....but you also need some info about just how this thing was wired to work in the first place.
Since the AT and MT version IAC are different and wired differently at the PCM, I wonder which ECM you have in it now? How did someone else get it to work?



Wiring: Looking at a diagram for 99-00
Simply, the yel/blk wire at the IAC is the power wire, shared withe power feed to the injectors and several other items. Same on both versions AT and MT.

On the 2 wire IAC version, the blk/blu wire goes to terminal B23 in the ECM.

On the 3 wire IAC:
the blk/blu goes to B6
the orange goes to B15

On some versions of the car, these wires would go to different spots at the ECM. If someone has done some swapping, it may take some investigation.

However, your current IAC code issues sure ought to be located in the area you were messing with.

HTH

civNC00

I decided to bite the bullet and replace the IACV after inspecting the connectors for signs of breakage and damage. Now the P1509 code is gone and the idle fluctuation has stopped.

Unfortunately, it is still misfiring. Codes are: P0300, P0301, and P0302. I'm going to rent a compression tester this evening and do that. Never done it before, so I'm going to follow this guide:
http://troubleshootmyvehicle.com/hon...-compression-1

Hopefully this will help me get to the bottom of things! I will continue posting results.

civNC00

Today, I rented a compression tester from O'Reilly Auto to check my cylinders. I checked 1 cylinder, and the rental tester unit detached at the lower press fitting on the rubber hose. (FYI: I only snugged it, did NOT over-tighten). It seems the rental unit was well worn. So, I took 15 mins to dig out the adapter from my spark plug hole, went back to the store, and bought a better one.

Anywho, this is the guide I was following:
http://troubleshootmyvehicle.com/hon...-compression-1

BTW, I am getting misfire codes on cylinders 1 and 2.

and these are my results:

Dry compression:
Cylinder 1 - 58 psi
Cylinder 2 - 38 psi
Cylinder 3 - 120 psi
Cylinder 4 - 150 psi

Wet compression
Cylinder 1 - 150 psi
Cylinder 2 - 105 psi

So, according to that guide, my piston rings are bad . Anyone want to give me a second opinion (or confirm) based on these results?

ezone

Son, them's some crappy numbers.

How many miles are on this?
Has it been overheated severely in the past?


----------------------------

If you can, screw the plugs back in and run it for a little bit to clear out the oil you pumped in. I do the comp test on a hot engine, unless there is a problem cold that leads me to think I need to do a cold comp check.

The oil you dumped in for the wet test must be equal in all cylinders, and use only a little bit. (How much did you use?)
If you dumped in too much oil (a pool sitting on top of the piston), you can artificially boost the compression numbers, giving false readings.


I don't do a wet test until after the valve clearances are verified and compression rechecked.
-----------------

test:
good battery fully charged. Cranking speed must be consistent throughout all tests. Battery charger running if you need to.

All 4 plugs removed.

I set the gauge where I can see it, or have someone else crank it so I can watch the gauge.

I keep on cranking until the gauge stops climbing. 8-10 hits or more, however many it takes to absolutely max out the gauge for each cylinder. Plus a couple more hits just to make sure it isn't going to climb any more.


After you get the numbers, now take off the valve cover and run the valve clearances. Adjust the valves if necessary.
Tight valves cause compression loss. And tight valves burn.

Now recheck compression again.

Still got low readings?
Now do a cylinder leakage test to determine where the loss is going.
Got an air compressor?

civNC00

175k miles. 2000 model civic. Owned since 2008. Has not been severely overheated that I know of since I've had it. It was however sold with a salvage title for very little money.

I didn't have a tablespoon like the guide said. I used a 1/4 cup measuring cup and I filled it about halfway full for each Cylinder. Not an exact science, I know.

I did not hook a battery charger to it. Probably need to. Yes I removed all four plugs. I had a helper start while I read the gauge. I didn't count hits, but I waited till it stopped moving to record the value.

One thing I noticed: when I tested Cylinder 2 wet, while starting, some of the oil shot out cylinder 3. Tried a few more times and it got to where the gauge would just peak with each hit. It wouldn't "climb" like it had been. I figured I was probably doing things wrong at that point, so I kept the initial numbers and that's what I posted.

I can get access to an air compressor. I will try some of your tips.

ezone

That might have been fuel from the injector?
I don't see how oil would migrate over to another cylinder unless you had a whole bunch in it.


And you might have been getting oil in the compression tester hose.
Sounds like it might have been too much oil?

IDK, just guessing.


Handy chart on my stove says 2 TBSP = 1/8 cup

civNC00

I guess I need to update this.

I've been really stuck lately on what to do, so I decided to take the car to my local mechanic. Went to drive the car to him yesterday, started the car, and it was blowing white smoke out the tailpipe continuously. I haven't started it at all since the compression test. So, I guess during the test I must've pushed the head gasket "over the edge" because it's definitely blown now. Mechanic is going to pull the head, refurb it and replace the gasket. It's been 100k miles since the timing belt (chain?) was replaced, and the manual says the belt should be replaced in that timeframe. How do I tell if it has a belt or a chain? I've heard if it has a chain you don't have to replace it. I was going to get him replace that as well if it has a belt, plus the water pump since they're so close.

ezone

You pumped a bunch of oil into the cylinders for the wet compression test. Remember?

That was just oil smoke you were seeing, it should have burned off after just a few minutes of driving as the cat and exhaust heated up.

Timing belt, not chain.

civNC00

Normally, I'd agree, but it didn't seem like oil smoke. It was very white. I stuck my face down at the tailpipe while it was running and it didn't smell like oil. It didn't really have a smell to it at all. Then, today, it acted similarly when I drove it to the mechanic's this morning. There was a strong scent of coolant inside the cab the whole way to his place. I suppose it was probably a mix, but I'm skeptical that it was all burning oil.

ezone

The mech should have been able to tell what the smoke was--- if it was still doing it when you got it there?

Coolant usually smells sickeningly sweet, even if it's in the exhaust steam.

HEY you had the IAC off a few times, and that rubber band gasket was probably hardened and flat. It could be the source of antifreeze getting in the cylinders?