Fluctuating Idle Problem - 2000 Civic

[00Civic]

Hello guys.....it's that time when I need someone's help on here. First time too.

Anyways, here's the 411. I just bought this car 2 nights ago for pretty cheap. It's a 2000 civic ex with a D15b7 motor in it.

Two issues. Fluctuating idle and bad transmission. ( I'm not worried about the transmission ) - Buying a new one within the week.

The idle issue is where I'm stuck at. It's going from about 1400rpm to 2000rpm back and forth. I came across a disconnected plug that was supposed to be in the IAVC, so thinking I fixed it, I plug it back in, no luck.

I've never had to deal with an IAVC and was wondering if anyone can point me in the right direction? Thanks!

[00Civic]

What voltage reading should I get if I were to test it to the body ground with the key in the (int) on position? I want to make sure it's not an electrical issue.

[*EFilliated*]

are you sure that was the right plug that goes to it? its IACV by the way

[00Civic]

There are two that can both connect to it, and I've tried both and no luck.

[00Civic]

I've just now sprayed it with a throttle body cleaner and in about 30 minutes, going to re-install it and see if it does the trick. I wanted to take this opportunity and volt-test it. I was wondering if anyone knew what the readings should be

[00Civic]

No luck. No difference at all. I'm going to check electrical before trying a new IACV. Where should I test for voltage? Any suggestions would be helpful.

[smoknlegend]

Remove and clean the iacv with cleaner then reinstall. Also check to make sure your cooling system is air free, air bubbles in there can cause idle fluctuations.

[00Civic]

Remove and clean the iacv with cleaner then reinstall. Also check to make sure your cooling system is air free, air bubbles in there can cause idle fluctuations.

Already cleaned and reinstalled it. No difference. No air bubbles in coolant hose. I need to find someone around the Macon area with an IACV laying around to test it.

[Theycall_Metue]

I came across a disconnected plug that was supposed to be in the IAVC
1:iacv is not a plug, its a hose. if it was disconnected, you'll be shooting out anti-freeze/water.
2: d15b7 is a obd1 motor. i hope its jumped to obd1 ecu and not obd2.
3: like above, it hope its not on p2p ecu, obd2 d16y8 vtec ecu.

4: idle like that is normally iacv, or a extreme vacuum leak


i would check the obd conversion first.

[00Civic]

I just double checked with the ECU identification chart.

Now I have a P2E(OBD II ) ecu that's for a 96+ Civic DX

Now I guess I am on the hunt for a P06 ecu!

[*EFilliated*]

Hmm yea u sir are wrong. Iacv does have a plug going to it so the ecu can determine location and compensate for any adjustment needed. If he doesn't have power/ground to it, it would cause this issue. And for 00civic I will try and find what readings u should get at the plug


1:iacv is not a plug, its a hose. if it was disconnected, you'll be shooting out anti-freeze/water.
2: d15b7 is a obd1 motor. i hope its jumped to obd1 ecu and not obd2.
3: like above, it hope its not on p2p ecu, obd2 d16y8 vtec ecu.

4: idle like that is normally iacv, or a extreme vacuum leak


i would check the obd conversion first.

[*EFilliated*]

How do u expect to go from obd2 ecu to obd1 without a jumper harness?


I just double checked with the ECU identification chart.

Now I have a P2E(OBD II ) ecu that's for a 96+ Civic DX

Now I guess I am on the hunt for a P06 ecu!

[00Civic]

How do u expect to go from obd2 ecu to obd1 without a jumper harness?

I am getting a jumper harness as well when I get the P06.

[*EFilliated*]

kewl try that


I am getting a jumper harness as well when I get the P06.

[RBS]

2000 civic EX, if you are using a EX engine harness then you have a bad IACV or vaccum leak. if it is not a EX engine harness, you will need to move ECU pin B6 to B23 and remove B15

[00Civic]

2000 civic EX, if you are using a EX engine harness then you have a bad IACV or vaccum leak. if it is not a EX engine harness, you will need to move ECU pin B6 to B23 and remove B15

Wouldn't the P2E (obd 2 ) ecu be causing the fluctuating idle if I have a obd 1 manifold? The back of the intake manifold says P06 HF 5.

[metalmatt47]

Hold on now, I'm confused. it's a 2000 model, but it's OBD1? I'm no Honda guy, but this makes NO sense to me. Maybe I'm wrong, but I'm pretty sure any car '95 1/2 and up were all OBD2, with some exceptions on '95/96 models.


Sounds to me more like a vacuum leak then anything. Either that or something is routed incorrectly.

[00Civic]

LOL, yes it's a 2000 model but the 92-95 civic motor is in it. Don't ask me. I bought it this way and couldn't pass up a good deal.

[00Civic]

if it is not a EX engine harness, you will need to move ECU pin B6 to B23 and remove B15

Is this in reference to a P2E ecu or an EX ECU?

[metalmatt47]

LOL, yes it's a 2000 model but the 92-95 civic motor is in it. Don't ask me. I bought it this way and couldn't pass up a good deal.

Ahhh that makes sense then. Not sure why someone would go backwards on an engine swap though :P

[*EFilliated*]

HONDA owners :headslap:


Ahhh that makes sense then. Not sure why someone would go backwards on an engine swap though :P

[00Civic]

You're telling me.

[RBS]

you need a p2p OBD2 ecu, or a Jumper harness & OBD1 ecu. p2e is a Y7/3 wire IACV ecu.

[00Civic]

RBS, you have aim or yahoo? real time messaging would be easier

[00Civic]

http://i51.tinypic.com/9bkrgg.jpg

[00Civic]

RBS, someone already repinned the B plug. Exactly the way you said to do. So, do I need a new IACV or a P06 Obd 1 ecu?

[candycoated]

mine had the same problem, it was my coolant.

[00Civic]

I'm going to try a new IACV on there to see if it solves the problem. If not, then I will go from there.

[candycoated]

goodluck!

[RBS]

RBS, someone already repinned the B plug. Exactly the way you said to do. So, do I need a new IACV or a P06 Obd 1 ecu?

try another ECU before anything else, you need a p2p (Civic EX Vtec) or a OBD1 computer.. any OBD1 will do

[00Civic]

try another ECU before anything else, you need a p2p (Civic EX Vtec) or a OBD1 computer.. any OBD1 will do

even OBD 1 automatic ecu's?

[*EFilliated*]

no it has to be 5speed


even OBD 1 automatic ecu's?

[00Civic]

no it has to be 5speed

That's what I thought, but he's the one who said " any obd1's would do ".

So anything that's obd 1 and 5 speed would work? are preludes, accords excluded from this?

[*EFilliated*]

i dont know about prelude/accord ecu. get a p28 or p06 5 speed. have u checked for vacuum leaks?


That's what I thought, but he's the one who said " any obd1's would do ".

So anything that's obd 1 and 5 speed would work? are preludes, accords excluded from this?

[RBS]

That's what I thought, but he's the one who said " any obd1's would do ".

So anything that's obd 1 and 5 speed would work? are preludes, accords excluded from this?


when i said any OBD1 ecu, yes i meant any OBD1 honda/acura ecu.... most automatic ecus will make the car DRIVE funny, but this is about the idle ;)

[Feriozfinest]

All u gotta do is clean the IVAC. They have video's on Youtube that show how to to do it step by step.

[Feriozfinest]

I had the same problem. Do waste ya money on a new IACV.

[00Civic]

So, here's my understanding / breakdown of what I've observed so far. I have a 2 wired IACV.

(92-95 civic DX motor ) used for 2-wired IACV's
(P2E ecu (96+ Civic DX ) for 3-wired IACV's - but there is not an orange wire ( which is used for the 3rd wire in the IACV )
(99-00 Civic EX harness ) used for 2-wired IACV's - No orange wire

At this point, it's looking like I might need to get a P06 ecu so that it won't look for the 3rd ( orange ) wire.

Here is the thing. The wiring harness that's under my hood is OBD2, would it be stupid to get an OBD1 ecu, or is there a way to keep this P2E ecu and solve this issue? Any suggestions/advice is welcomed.

[00Civic]

ORRR

Should I just get the P2P ecu so that it doesn't look for the 3rd wire?

[00Civic]

Anyone who can solve this issue will get $50. No joke. If your idea/suggestion works and fixes the problem, I will be more than glad to pay the $50 =).

[*EFilliated*]

put it this way when it comes to having stock motors, u use whatever ecu is meant for the motor regardless of what chassi it is in. once u get the correct ecu for the motor that is in your car u can start looking somewhere else if the problem remains, the ecu is the brain to how the motor will run period. without having the correct ecu to begin with, it will just cause you to waste money and time trying to diagnose a problem that may not be there.

[00Civic]

I've already made that suggestion to my brother and he said it would be a waste of money to do that, but the hell with it. I will just try my luck and go for it.

With that being said, anyone have a P06 ecu and a jumper harness for me to test it on? Long shot, but it's a start!

[*EFilliated*]

OBD2 is way more advance then obd1, any little thing that it doesn't find correct it will basically shut the car down and prevent it from operating normally until problem is fixed. OBD1 is not as advance and doesn't look for half the things that obd2 does, tell ur brother to stop being hard headed and fix the problem the right way.


I've already made that suggestion to my brother and he said it would be a waste of money to do that, but the hell with it. I will just try my luck and go for it.

With that being said, anyone have a P06 ecu and a jumper harness for me to test it on? Long shot, but it's a start!

[00Civic]

^^ makes sense.

I'm still looking for a P06 ecu. Can't seem to come across any. LMK if you do!

[00Civic]

I picked up the P06 ecu today, and now need a OBD 2 to OBD 1 jumper harness.

Do I need the OBD2A to OBD 1 harness or the OBD2B to OBD 1 harness? What is the difference between the a/b? JW

[Tech5]

OBDII A is for 96-98 civic ,
OBDII B is for ONLY 99.00 civic

the whole harness is completely different

[00Civic]

UPDATE:

Bought P06 ECU
Bought OBD2 to OBD 1 jumper harness
Bought EX manual transmission.

I will be installing everything at some point this week. Hoping to get this thing on the road by the end of the week!

[00Civic]

UPDATE:

Installed new transmission ( with Honda MTF - TY Chris! ).
Installed P06 (OBD 1) ecu w/jumper harness.
Installed new axle.

I am still having a fluctuating idle, and I'm still scratching my head on this issue. Anyone have any ideas? I don't have a throttle body gasket , and am going to pick up one tomorrow. I'm hoping this will solve the issue. My brother peered inside the throttle body and said there wasn't a gasket. Would this cause the fluctuating idle?

Also, I have a custom header ( with no oxygen sensor bung ) and no primary oxygen sensor, but my secondary oxygen sensor is already plugged in. Should I wire up the primary to the secondary so that it reads as one? Would the missing primary oxygen sensor be causing the fluctuations?

I need guidance!

[*EFilliated*]

a throttle body without a gasket would definetley cause the idle problem, that is considered a vacuum leak. the missing o2 wont cause the idle problem but ur car will be off on air to fuel ratio. if u have a CEL for o2 fix it




UPDATE:

Installed new transmission ( with Honda MTF - TY Chris! ).
Installed P06 (OBD 1) ecu w/jumper harness.
Installed new axle.

I am still having a fluctuating idle, and I'm still scratching my head on this issue. Anyone have any ideas? I don't have a throttle body gasket , and am going to pick up one tomorrow. I'm hoping this will solve the issue. My brother peered inside the throttle body and said there wasn't a gasket. Would this cause the fluctuating idle?

Also, I have a custom header ( with no oxygen sensor bung ) and no primary oxygen sensor, but my secondary oxygen sensor is already plugged in. Should I wire up the primary to the secondary so that it reads as one? Would the missing primary oxygen sensor be causing the fluctuations?

I need guidance!

[00Civic]

I've already made it a priority to hit up the honda dealership or autozone to get a gasket asap.

[lilhomie8913]

dude this is a comon honda problem is call your fast idle controll valve is contrlled by coolant its usually located under the t-body take the t-body off and the valve under it has a late with two 8mm bolts take them out and with a flat head screw driver twist the little plastic thing all the way dwn this should fix your problem. et me know if this helps you.

[00Civic]

UPDATE:

I installed the new throttle body gasket, and while I had the throttle body off, I took the time to inspect the FICV ( Fast Idle Control Valve ) and noticed that it was LOOSE all the way out. So I proceeded to twist it all the way down ( closed it ) ( as per se lilhomie's advice ).

This momentarily stopped the fluctuating idle for a few minutes, BUT, it was still a very rough idle. After revving it some more, the fluctuating came back, but only from 1000-1500 instead of the 1500-2000 where it was at.

I, then checked the radiator and filled it up with water. I turned the car over and the fluctuating idling went away, but the rough idle is still there.

What should I do next?

[00Civic]

UPDATE:

Right after I made the last post, I went out and put back in the original P2E ecu, and presto! The rough idling went away and it's idling pretty good at 1k.

The whole time....the whole time...it was the fast idle valve. Damn you FITV

[*EFilliated*]

And the gasket


UPDATE:

Right after I made the last post, I went out and put back in the original P2E ecu, and presto! The rough idling went away and it's idling pretty good at 1k.

The whole time....the whole time...it was the fast idle valve. Damn you FITV

[lilhomie8913]

UPDATE:

Right after I made the last post, I went out and put back in the original P2E ecu, and presto! The rough idling went away and it's idling pretty good at 1k.

The whole time....the whole time...it was the fast idle valve. Damn you FITV

i should get some rep for that.lol

[00Civic]

Actually, I read a website blog on Idling issues, and it told me to do it. I hadn't looked at your post until after. But I'll try and give you reps anyways!

Here is the website. It was VERYYYY helpful.

Mods: You're more than welcome to make it a sticky!

http://ef-honda.com/ben/Badidle.php