Erratic Idle Fix
Required Tools:
Basic Socket Set
Basic Wrenches
Pliers
Hammer (to tap loose tight bolts)
Throttle Body/Carb Cleaner
Gasket Sealer
::Introduction::
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...
Required Tools:
Basic Socket Set
Basic Wrenches
Pliers
Hammer (to tap loose tight bolts)
Throttle Body/Carb Cleaner
Gasket Sealer
::Introduction::
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...
Anyway, enjoy kids and see you next time...
Comment