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Hi all,

I'm pretty new and 'wet behind the ears' when it comes to doing repairs to my car. I'm looking to learn a little more and hopefully start to carry out some more minor pieces of work myself.

I currently have a couple of warnings being thrown up by the car (Mixture too lean in idle - banks 1 & 2). I did some research on this forum and found several posts suggesting that the Crank Case vent valves and hoses can cause this issue. So I thought I'd have a crack at replacing them myself. I found some really good DIY guides on this forum for carrying both pieces of work and I'm pretty confident I can follow them.

However, I thought that whilst I have the engine cover off it might be an idea to clean the air intake and the MAF. This is where information I'm finding online seems to conflict.

Firstly, is it a good idea to attempt to clean the MAF sensor? I do occasionally get a minor shake whilst the car is idling. Could cleaning the MAF sensor fix this? I have seen some posts that strongly advise against doing anything with the MAF sensor unless you absolutely have to. I know not to touch the sensor or wiring - I was just going to spray some electrical contact cleaner through the section of pipe that houses the MAF.

Secondly, when it comes to cleaning the throttle air intake: Is it safe to move the butterfly or am I going to cause issues with the motor? I even saw one video where the chap was saying that motor controlling the butterfly can snap shut and take your fingers off - although that sounded a little far fetched. Is it advisable to remove the whole intake and clean it or can you do a good enough job from the outside with just some air intake cleaner and a lint-free cloth.

Lastly, is there anything else you'd suggest changing/cleaning whilst the cover is off?

Thanks in advance for any tips.
 

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They make a can of sensor cleaner but unless you see lots of dust in the intake tube past the filter I wouldn't think there would be a need to clean it. Start with the valves and possibly the tubing feeding them. The main throttle body opens and stays open when engine is running. Engine speed controlled by adjustable intake valves.
 

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If you are having a lean condition, I would inspect all of the sensor o-rings, & go ahead & change both Eccentric Shaft seals. This is a known problem causing un-metered air getting inside the engine. The CCV seals on both valve covers are a good PM job. Also inspect the 2 CCV vent tubes, which are very easy to crack while removing them. The tubes get very brittle over time. If you clean the MAF sensor, only use MAF cleaner, & do not touch the sensor by hand. Once you clear one of the 2 banks problems, you can focus on the one that is left. Make sure your dip stick is pushed all over the way down, & inspect the oil cap seal to make sure it is also sealing.
 
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