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ENG: Erratic Idle Fix

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    ENG: Erratic Idle Fix

    Erratic Idle Fix

    Required Tools:
    Basic Socket Set
    Basic Wrenches
    Hammer (to tap loose tight bolts)
    Throttle Body/Carb Cleaner
    Gasket Sealer


    Well it seems that many people are having this problem where their car's idle will surge up and down either when the car is cold, when it is hot, or all of the time. I personally just spent a month trying to figure this problem out and I can honestly say that it is one of the most confusing things I have ever had to solve. I found many posts on this site related to this problem but most of them only had one or two suggested fixes. Well as it turns out my solution wasn't even one of the recommended ones and it took me a month to finally try it so hopefully this thread can be a knowledgebase of how to fix this very irritating problem.

    ::Eliminate the Obvious::

    My first step to solving my own idle problem was to first eliminate anything that I know for certain is wrong. My car was throwing two trouble codes when I first purchased the car. You will be able to tell if you have stored codes because your check engine light (CEL) will be lit up while driving.

    You must first check these codes by finding the small diagnostic connector under the passenger side dash. It's tucked away sort of behind the small kick panel under the glovebox, no tools required, just pull on the panel to remove it. Once you've found the connector you have to short the two prongs inside of it, I found the easiest way to be to stick a flathead screwdriver in there and cross the two terminals.

    Now turn your ignition to the ON position, but don't actually start the car. Your check engine light should blink a certain number of times. A long blink stands for 10 and a short blink stands for one. For instance 22 would be represented by two long blinks and two short blinks, or 43 would be represented by four long blinks and three short blinks.

    Ok, my car was throwing two codes. Code 5 which is for the Manifold Absolute Pressure (MAP) Sensor, and Code 41 which is for the Oxygen (O2) Sensor Heater.

    The MAP sensor is located inside of this box.

    This is a picture of me holding the MAP sensor that I picked from the junkyard. There is a small vacuum hose that connects to the bottom side of it where the arrow is pointing. The other arrows are pointing to the vacuum line that runs to the MAP sensor.

    I replaced the MAP sensor with the one I procured from the junkyard and then replaced the vacuum line that runs to it as well. Also take car to inspect the little "T" junction that the vacuum hooks up to inside of the black box to make sure it's not cracked or otherwise broken.

    I then reset my ECU by removing the negative terminal from my car's battery and removing the 7.5v "Radio" fuse in the under-hood fusebox for a few minutes. After starting the car back it was no longer throwing a code for the MAP sensor. That's one down.

    Now it was time to tackle the Oxygen Sensor, which was really no problem. I simply purchased a new O2 sensor, removed the old one with a 22mm wrench and installed the new one. Reset the ECU again and that code is gone.

    ::Cleaning Out Everything::

    Ok, now that my car isn't throwing any codes I can rule out that they are the cause of this problem. The car does run noticeably better, but the idle is still surging at this point. Let's take a look at the first item we're going to worry about cleaning out, the Exhaust Gas Recirculation Valve (EGR). What this valve does is open up during cold weather to allow warmer engine bay air into the intake manifold to help warm the car up faster. It is notorious for getting clogged with carbon deposits. Typically a malfunctioning EGR will not make your idle surge, it will usually just cause the car to run incredibly rough, but we're not leaving any stone unturned.

    Cleaning your EGR is pretty simple and straight-forward. Just unplug the electrical connector going to it, remove the vacuum hose, and then remove the two bolts that hold it in place. These bolts can be a severe bitch. They're kinda under the EGR itself so using a 3/8" drive socket extension is out of the question. What I found to work nicely is to use a 3/8" ratchet with an adapter to go the the smaller (forget the size) or sockets and extensions. Then use a long extension and 12mm socket. If the bolts are really hard to get off just use a small cheater pipe for some extra leverage.

    Once off just spray down the inside of the EGR with some carb cleaner until it runs fairly clear. Re-installation is the reverse of removal.

    The large arrows points out the EGR Valve which is located behind the distributor cap, next to the thermostat housing, and in front of the throttle body. The small arrows point out the two bolts that hold it in place, please note that one of them is behind the valve, you just have to look for it.

    Now to clean out the Idle Air Control Valve (IACV). This little bugger has been discovered to be the cause of many idle problems before, so there is a chance you won't have to go any further past this step to fix this problem. The picture below shows you the IACV and the two bolts and the connector that must be removed in order for you to be able to remove it. There will also be two coolant lines running into it that are hard to see in this picture.

    Ok, now that you have the IACV off you can test it to make sure that it is even working at all. If you run two wires from your battery, one negative and one positive and touch them to the two terminals according to the picture below you should hear a click noise and if you can see the back of the IACV or have someone else watch it when you hook up the power you should see the little spring compress through hole A pictured in the second picture below. Oh, and I should mention that you should be really carefull about having two lives wires comming directly from the battery that close to each other. If they come into contact they will arc pretty badly. It happened to me in fact, well actually my wife because she was doing the wires while I was holding the IACV and it scared the crap out of her, lol.

    If all is well and you hear the clicking noise (and/or see the spring compress) when the power is applied then your IACV should theoretically be good. On to cleaning it. There are two different methods that I have heard about and each seem to work. First off you can just squirt some carb cleaner on the end of a q-tip and clean the little screen (B in the picture above). The second method is just to simply spray carb cleaner all over inside the IACV, which is what I did. As a side note you may also want to blow into one of the little coolant passages in the IACV and make sure that air is comming out of the other side. If it is that means that the IACV is getting an ok coolant flow. You may also want to blow into one of the coolant passages while plugging the other with your finger to make sure that the coolant passages aren't leaking into the interior of the IACV. If all is good simply re-install the reverse of removal.

    Ok, now onto the FITV (Fast Idle Thermo Valve, I believe). It is pictured below and removes very similarly to the IACV, go ahead and remove it from the car.

    You can now clean it out much like you did with the IACV. Once that's done you can go ahead and remove the two little screws and the plate on the top of it as pictured above, and here's where it gets a little strange. As pictured below the FITV has a little plunger type thing inside that needs to be tightened down (flathead screwdriver works great), but there is a catch. It's supposed to be tightened down while hot.

    What's seems to have worked for many people is to take the FITV into your house, put a large pot of water to boil, and then once it is boiling drop the FITV into it for a few minutes. Once the FITV is hot remove it (carefully of course) from the boiling water and tighten down the little plunger as far down as it will go. You can now re-install the FITV onto the manifold and we can move on.

    continued below...
    Last edited by Torqstr; 08-03-2006, 09:44 PM.
    I read somewhere that marijuana effects the memory. For some reason I can't seem remember where I read that. -- max sideburn(aka torqstr)

    "Those who would sacrifice liberty for security deserve neither." - Benjamin Franklin

    CB7: The Movie TEASER VIDEO

    ::Bleeding Your Coolant::

    Bleeding the coolant you say? I know, I thought it sounded absurd too, but Honda is strange and if your coolant system has bubbles in it there is a chance that it will affect your idle and can easily cause this idle surging problem.

    The first step is to located this little "bleeder nipple" which is located on the thermostat housing.

    You will need a ratchet with an extension and a 12mm socket. Remove the radiator cap, then loosen (but don't remove) this little "nipple". Now proceed to fill up your radiator and watch the little bleeder "nipple". At first you will probably see bubbles comming out of it but eventually it will be a steady stream of coolant. Now tighten down the "nipple" and close the radiator cap.

    ::Other Possible Causes & Solutions::

    1.) You can check for vacuum leaks fairly easily. Just get your can of carb cleaner and while the car is running spray it around where the manifold meets the head, around the throttle body, and around anywhere else gaskets may have failed. If you spray the carb cleaner and the engine revs you will know that the carb cleaner is somehow getting into the manifold and that you have a leak.

    2.) Inspect all of your vacuum lines for cracks or holes

    3.) Pull and check your main relay. Main Relay Repair Tutorial

    4.) Check that you have good ground wires going from battery to transmission, battery to engine, chassis to engine, chassis to transmission, and even add a few if you have to. Also don't forget to check the ground just under the thermostat housing, it can easily become corroded and fail.

    ::If All Else Fails::

    This little thing shown below is called an "Air Boost Valve".

    When I got the car it was simply blocked off, so I decided to re-run a line from it to the intake to make sure it wasn't the cause of the idle problem. Well I popped off the cap on it a little while ago and a spring flew out (watch your eyes) and I lost the little lid for it, but when I started up the car....IT IDLED RIGHT!!!

    Well I noticed that if I have the car running and then push down on this little valve (like the spring was doing) the car's idle starts jumping up and down again, but when I take my finger off of it the idle returns to normal.

    ::In Conclusion::

    What did we learn today? That if you're stubborn enough and don't mind spending a month on something you can eventually figure it out. If you've gone through this entire howto and still have the surging idle problem then at this point I would actually say maybe you should take your car to a dealer or trustworthy mechanic (and I'm not the kind of person to advocate that). If you're problem still isn't fixed you can post here and we can try to work through it, but I think that the limit of CB7Tuner members' knowledge on this subject has almost completely been compiled here since it took me a month to find all of this stuff.

    Anyway, enjoy kids and see you next time...
    Last edited by Torqstr; 08-03-2006, 07:12 PM.
    I read somewhere that marijuana effects the memory. For some reason I can't seem remember where I read that. -- max sideburn(aka torqstr)

    "Those who would sacrifice liberty for security deserve neither." - Benjamin Franklin

    CB7: The Movie TEASER VIDEO


      hmm im gonna do that coolant thing, didnt know that could be done, thanks!
      You have been defeated by a car with child locks, how embarassing...

      "I noticed my f22 felt "healthier" until it blew up." <Myk>


        This is a very helpful Diy Thanks


          cool. if this helps you fix your erratic idle problem let me know. I'm curious about this problem since it seems to be so prominent in these cars.
          Last edited by Torqstr; 08-03-2006, 09:48 PM.
          I read somewhere that marijuana effects the memory. For some reason I can't seem remember where I read that. -- max sideburn(aka torqstr)

          "Those who would sacrifice liberty for security deserve neither." - Benjamin Franklin

          CB7: The Movie TEASER VIDEO


            wow...nice DIY
            Signature Picture removed due to excessive size

            VOLVO 240GL bandit crew....all mighty supertank


              mine was the IACV but it still kinda idles rough.

              however i havent touched the EGR, starting valve or the FITV.

              thanks for the DIY!
              I <3 G60.

              0.5mm Oversized Stainless valves and bronze guides available. Pm me please.


                Thanks, I've recently been reading up on a lot of these things to do to fix the idle problem. I don't really have an idle problem just I idle at 1500rpm so it's about double normal idle and I figured this would fix it. You mentioned a couple thing I didnt know, like the coolant, EGR, and the other springy thing. One thing you didnt mention was cleaning the EGR ports, heres a link to the DIY on cleaning the EGR ports.


                Thanks for making the DIY, it clarified anything I was unsure about. Also I hear Sea Foam helps clean out everything and fix idle problems sometimes but I'm scared to use it haha.

                btw, when you drop the fitv into boiling water should the top cover be on it? and that springy thing, did someone just unhook it on your car or forget to re attach it or is everyones unhooked?


                  i dropped the FITV into the water without the cover on.

                  also please feel free to add to this DIY. I just wanted to give some nice clear directions with good pictures
                  I read somewhere that marijuana effects the memory. For some reason I can't seem remember where I read that. -- max sideburn(aka torqstr)

                  "Those who would sacrifice liberty for security deserve neither." - Benjamin Franklin

                  CB7: The Movie TEASER VIDEO


                    good shit mang, going to be doing this tomoto.

                    Not my fault my dick only fits magnums.
                    Why drink and drive when you can smoke and FLY?


                      Originally posted by amd3dnow3
                      good shit mang, going to be doing this tomoto.
                      lol tomoto


                        yea my car need a little tune up so ill be doing this tommorrow
                        Last edited by Davids92Accord; 04-09-2011, 03:24 AM.

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                          [QUOTE= tommorrow[/QUOTE]

                          Tomorrow (pwned)
                          You have been defeated by a car with child locks, how embarassing...

                          "I noticed my f22 felt "healthier" until it blew up." <Myk>


                            Originally posted by Davids92Accord
                            i think i might clean out my EGR valve this weekend food write up bro


                              Air boost valve is suggested to be block off with a plate for aggressive camshafts, as they have lower vacuum at idle. It will help idle smoother.
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