Good Afternoon,

Just to give some info about the car, I bought myself a 08' Audi A4 base little less then a year ago with about 87k miles on it now from 70 something from when i bought it. So far, besides the oil change every 3k, I had to replace my 1080 valve which got done by certified Audi dealer. Other then that i haven't really changed nothing else. Now for the issue..

Once I turn on my car, anytime, it's idling @ around 1-1200 RPMs. I don't know to much about cars but enough to know that isn't good. Kinda curious to the solution to this, and i was thinking maybe a tune-up to solve this but like i said i don't know to much. Also when i have my AC running, i can kinda hear something, popping? Like if air is getting jammed and when it comes to much it releases making a pop noise, but its repeatedly fast, the noise. I can feel/hear it under the driver seat floor.


I would appreciate any advice/help to figuring out what could be the problem. I really wouldn't want to go to a dealership, pay for a diagnosis and have to pay premium. Might be able to get it down myself if simple but any help would be great. Thank you all.

 

Idle does seem a bit low. This that with the AC off as well? Mine drops when I run the AC. Only thing I can think of would be a bad coil pack. I would think you would be throwing a code for that. Might pull your codes to see if anything is stored in there.

Not sure about the AC popping issue. I think there is a duct that runs under the seat to send the air to the rear of the car. Might want to look inside there and see if a piece of paper or something in stuck in it.

 

Hmmm... 1000 to 1200 RPM for the first minute or two is alright... it means the Cold Start system is functioning. After that 550 to 650 is about right. USUALLY fast idle is associated with a vacuum leak. Get a can of MAF/MAP cleaner and spray the hoses that carry vacuum. If the idle goes DOWN, you have found a leak. Plug same..

 

Yes, that happens when the AC is off. It happens immediately when i start the car. I was told i'm able to pull up some info about it from advance auto parts, which i'm going after work so ill keep you guys posted by Monday. I also heard it could be a sensor, had a friend have the same issue and said a sensor fixed it.

Still clueless about the AC noise too. Kinda nervous to keep it on, afraid to hear/feel a loud pop and something break. Going to be hard, the fact that summer is coming around and im in Florida..

 

Actually, I think your idle is a bit high, not low. When I first start mine (2.0T engine), it idles around 1000-1100 and then after the startup tests run and everything starts to warm up (20-30 seconds, I think), it drops back to around 800 RPM and idles there from there on out. I'm not sure if these engines have an idle air control module/sensor or a throttle position sensor--I've had those go out in another car causing a similar problem. Also, you could check airflow from your duct to the intake. A lot of times, weird idles can be due to air problems.

Have you had the PCV/fuel sensor customer service action done? These had notoriously bad PCVs (another potential idle culprit) and Audi created a service action where they replace the PCV, low pressure fuel sensor, intake runner motors, and maybe one other thing. Been a while since mine had it done, so I don't remember all the details and I don't even remember if it applied to '08s, but I would check with an Audi dealership about it. Most of those are limited to 10 years/120k miles, so don't delay too long.