Hi All,

Anyone had a chance to read my previous post BMW E36 M42 DISA Valve and check the DISA valve for me? Come on, no one with M42 engine? or are you afraid to discover a problem in your engines?

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As you may know, I’m facing trouble with my BMW E36 318is idle and until now, I was unable to totally fix the problem. I’ve cleaned the ICV, changed oxygen sensor, checked for vacuum leaks but this didn’t solve my problem. I still have a problem in one of the knock sensors, but mechanics say that it doesn’t affect the idle in anyway. Well, although this may sound correct, but I’m going to change it anyway simply because I hate to have such a problem in my car which may cause some damage to the engine.

Now, I’ve discovered last week that my DISA valve doesn’t close. For those who don’t know what the DISA valve is, please check here and here.

I’ve tried to reach to the DISA valve and check to see if the actuator arm retracts if I turned my engine on and below 4,700 RPM. I found out that the DISA valve doesn’t close and I think this may affect the idle although I’m not 100% sure of that.

So, what I’m looking for is some help from you guys. Anyone with M42 engine can confirm that the DISA valve actuator arm retracts when you start your engine. To check that simply:

1. Reach with your hand behind the DISA diaphragm.

2. You should feel a small arm that you can press with your finger when the engine is off.

3. Now, according to the Bentely manual, the actuator arm should retract when the engine is started (at idle).

Now, can you feel the actuator arm retracts when the engine is started? Can you please confirm this?

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Rough idle problems are really common on BMW E36 cars and there are a lot of problems that may cause this to appear. First I will show you a video of such a rough idle and then list the possible problems that may cause that.

Take a look:-

The possible reasons for such a problem are:

1. Oxygen Sensor is gone: You can run a diagnosis to see if this is the problem. If you find out that it’s the problem, you should replace it. Read Everything you need to know about Oxygen Sensor! for more information about oxygen sensors.

2. Idle Control Valve: Dirty idle control valve is a very common problem in BMW E36 cars that may cause rough idle. You can use this DIY (Do It Yourself) to learn about Cleaning E36 ICV (Idle Control Valve)

3. Plugs and Distributor: You may need to replace these to solve your problem. I however don’t have a way to check them before replacement.

4. The Throttle Position Sensor (TBS) and/or connections may be bad: You can simply disconnect it and see if your problem is solved or not.

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