The bmw e36 idle control valve is an incredibly important component in your vehicle’s performance. The ICV regulates the car’s idle based on how much air is getting to the motor. Idle Control Valves typically have two components to them, a sensor that sends information back to the computer and the actual valve which opens and closes.
Most idle control valves are located somewhere on a vehicle’s intake manifold. Some, such as the one on my Ford Ranger, takes about thirty seconds to remove and replace, whereas others such as the valve on my four-cylinder e36 can take well over an hour of your time. A failed idle control valve can cause a number of issues in your vehicle, to the point where it will stall out.
In this article I will discuss the symptoms of a bad ICV, the four cylinder and six cylinder E36 ICV removal process, and how to clean the ICV.
You can pick up a high quality Bosch E36 idle control valve here.
This video shows you how I diagnosed a bad idle control valve, how to get to the idle control valve on a 4 cylinder E36 and how to clean out the idle control valve!
Faulty ICV Symptoms
Check Engine Light
Clogged idle control valves do not cause a check engine light to pop up on an E36. However, if the motor inside the valve is fried, this will send a signal to the ECU and result in a check engine light. This is definitely the easiest symptom to notice. Be forewarned however, if the electrical component on the idle control valve is bad, no amount of carb cleaner will make the valve work correctly again. You will have to replace the valve.
When I began noticing an idling issue in my brother’s vehicle, initially the car would start and the rpms would bounce up and down for a minute before finally leveling off. I figured this was not a vacuum leak, because of the eventual leveling off of the idle. Idle Control Valves typically give you a warning in the form of either an odd idle or a check engine light, before they fail completely and the car stalls out.
Idle Control Valves typically get clogged overtime with carbon deposits, and typically need to be cleaned or replaced every 80,000 miles. When I cleaned out the ICV valve on my little brother’s 318i, his vehicle wouldn’t even hold an idle. A clogged idle control valve will exhibit similar symptoms to a failing motor, except that it won’t throw a check engine code.
Another giveaway that the IDC has failed is that the vehicle won’t hold an idle without you putting your foot on the gas. This is what happened when I was repairing my brother’s car. is car would refuse to hold an idle unless you held your foot on the gas pedal. Usually an idle control valve will not get this bad to cause the car to stall, but it does happen.
Before You Clean the Idle Control Valve
Before cleaning the ICV I would suggest examining the vacuum lines. Cracked vacuum lines can cause similar symptoms to a faulty idle control valve. An extremely common occurrence for BMW’s is for the main intake boot (connects to the throttle body and idle control valve) to develop a hairline crack. It does not have to be a huge crack to cause an idling issue, and I have seen this boot crack on every E36 I have ever owned.
If you have some mass air flow sensor cleaner hanging around go ahead and clean the mass air flow sensor before you go through the trouble in accessing the idle control valve. A dirty air flow sensor can cause similar symptoms and it does not always throw a check code!
A few other common vacuum leak sources include: Brake booster hose, CCV Valve, Check Valve vacuum line underneath the intake manifold.
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Idle Control Valve Location
New BMW owners may be surprised at the location of the ICV on their vehicle. On most American cars the ICV is extremely accessible at the top of the intake manifold Typically, they can be removed and cleaned without having to remove any other parts. However, BMW’s are different, especially the four cylinder 318i.
The ICV is located underneath the intake manifold on BMWs, which makes the process of cleaning the ICV significantly more involved.
The six cylinder BMW ICVs can be accessed without having to remove the intake manifold, however the four cylinders require removal of the upper intake manifold to gain access to the ICV.
Four Cylinder ICV Removal
To get to the four cylinder BMW ICV the entire upper intake manifold must be removed. Because of this, I highly recommend that you replace several other components when you remove and clean the ICV. The PCV valve is also located underneath the upper intake manifold, and there are vacuum hoses that connect to the fuel injectors that nine times out of ten will be cracked.
11 mm socket
1/4 drive ratchet
Flat head screwdriver
- Begin by removing the air box and intake boot to the throttle body.
- Next you need to remove the throttle body, which is held on to the manifold by four 11 mm nuts.
- The ICV hose is connected to the back of the manifold, it can simply be twisted off.
- There are five 11mm nuts holding down the upper manifold, they need to be removed. The one in the back is more difficult to reach, however a small ¼ drive ratchet should take care of it.
- Once the manifold is removed you will have access to the ICV, it will have two hoses on either side of the valve, an electrical connection, and will be held down by a rubber strap.
- Remove the ICV, take a can of carb cleaner and spray into the valve. I give the ICV a liberal spraying, and then shake the valve to let the carb break up. Afterwards take a screwdriver, and attempt to open and close the valve. If the valve refuses to open at all, set the valve down and soak it in carb spray, and let it sit for several hours.
- Once this is done the valve should move freely, one way to test if the ICV has an electrical issue is to plug it back up and turn the key in the ignition to clicks. The ICV should “prime”, and open up, if it doesn’t you more than likely have an electrical issue in the ICV motor.
- Once this is completed simply re-install the hoses and upper intake manifold, and start up the car.
Six Cylinder ICV Removal
Luckily for us six cylinder owners, the idle control valve removal is a less involved process. No need to remove the intake manifold, however you will need to remove several things to gain access to it. My advice if your pulling the valve is to go ahead and purchase the ICV grommet as well, along with a throttle body gasket if you have not pulled and changed it recently.
- Start with removing the air box and cruise control module, 2 ten millimeter nuts hold them onto a bracket. Afterwards the box is easily removed by disengaging two clips
- Remove the intake boot by loosening the clamp that holds it onto the throttle body. The hose that you must detach at the bottom of the boot runs directly to the idle control valve.
- If you have the secondary throttle body remove that and then the primary throttle body. The primary has four ten millimeter bolts holding it onto the intake manifold. There is a gasket in-between the throttle body and the manifold that I would advise to replace. No need to disconnect the throttle body, just push it out of the way.
- At this point you need to remove the single ten millimeter bolt holding the dipstick tube to the intake manifold bracket.
- There are two more bolts that secure the ICV bracket to the intake manifold, remove these bolts.
- At this point, simply pull down on the ICV and it will pop out with the bracket.
- Consider replacing the hose that connects the ICV to the intake boot, especially if it has deteriorated.
- Note that upon re-installation you should put some silicone lubricant along the edges of the ICV grommet.
Cleaning the ICV
I use carb cleaner to clean out the idle control valve. Don’t worry your not going to damage any electronic components as long as you spray in the valve. If the valve is really gunked up, let it sit in carb cleaner for several hours and then take a shop rag and clean out the inside of the valve.
You can also take a small flathead screwdriver and open up the valve, once you have it opened spray the crap out of it and watch the black colored spray come out on the other side of the valve. Once you are satisfied with your cleaning and you’ve allowed the idle control valve to dry out you can reinstall it!
I hope this article has helped you out with your idling diagnosis! If your curious about other repairs related to fixing a rough idle check out this article!