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I've been having an issue with my idle this last few months and I really want to try and get it sorted. I can best describe it as a pulsating idle that I can feel coming through the car. When the car is cold and only started I can hear the idle fluctuating but when it's warmed up you can't really hear it, but you can feel it. Hard to describe without sitting in the car lol.

In an attempt to sort it I carried out some of the steps mentioned in the DIY: forgotten tune-up mods here. I carried out the following:

• Replaced the primary o2 sensor - It was giving the odd error code now and again
• Cleaned the throttle body
• Cleaned the Idle Air Control Valve
• Upgraded to a K&N 57 Series Gen II short ram kit - air filter was dirty and I was already planning this upgrade regardless of the idle issue

I was going to clean the EGR valve but I couldn't get my sockets onto the nuts properly, especially the front one. Could a dirty EGR valve cause this?

I also read that it could be a vacuum leak. I think I identified some of the vacuum pipes but I am not 100% sure so guidance on what pipes are vacuum would be fantastic.

The car just hit 140,000 miles and along with the rear sway bar link snapping last weekend the alternator died yesterday. Not been having great luck this week with the car so need all the help I can get.

 
Rep Power: 211

do you mean the idle goes higher then lower, and repeats that process by itself?

if so, that is a sign of an intake leak, the engine is sucking in air somewhere between the throttle body and the head, could be the intake gasket itself that is leaking/not sealed properly, but that is only one of several possibilities

 
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Yes, when the engine is cold you hear the rpm go up and down and see the rpm needle go up and down (not 100% sure on the needle movement). When then engine has warmed up you can't really hear the fluctuation, but it feels as if the idle rpm is trying to change very vast causing a pulsation feeling to come through the car. I will try and record a video of the cold idle this morning, just hope my phone mic is sensitive enough to pick it up.

 
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I completely forgot to say that starting the car when cold is harder than normal. When warmed up it's usually OK starting. I always wait for the fuel pump to prime everything before I try to start the car.

 
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Here is a video I did of a cold start and idle. Of course it started ok this morning when I wanted it not to. Anyway, you can see (I hope) the rpm needle going up and down and when I go around to the engine you can hear it fluctuating a bit.

[youtube]http://www.youtube.com/watch?v=rcufzRpxPvc[/youtube]

 
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i dont really see or hear anything wrong in that video, it seems to be idling normal

 
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^^Agreed. Faster idle speed when cold is normal, and it comes down as the engine warms up.

I did not notice any significant fluctuation from here.

 
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I noticed that while I'm out now. I'll record another on when it does itt again. Of course it would behave when I'm trying to demonstrate the issue