So I'm new to EP3's. I just bought one for a daily and it is nice and great, yeah. Well, when I turn the A/C on at idle, it will sometimes produce this bizarre knock, which at first freaked me out when I was test driving it, but I figured out it wasn't the motor itself. The noise is synchronous with vibration as well. Sometimes when I go from idle to a blip, for a split second I hear the noise. Sorta like the same thing that happens when you have an exhaust rattle @ a certain RPM. Once I am under load or above 1200ish RPMs, it goes away.

Is there something obvious that y'all might know about? The car has a warranty, but if it's gonna be something easy, I'd rather do it myself since I'm used to doing all my own work.

Thanks.

 

where in the car is the knock/vibration coming from?? Is it from the rear left/right corner??

 

take it in, esp if its the ac. mine went out at 40k and the compressor is like $700!

 

i got knocking noises...but it's just my cat hitting my d3 brace. maybe you have a loose heatshield or something

 

Is your EP stock or modded? Maybe the previous owner had ESSM's in there and it really vibrates when you turn on the AC...

 

It's stock. It's not the compressor because it does it with the A/C off as well. I heard it for a split second when the fan kicked on yesterday.

 

well ... just from my experience with the EP bucket ... the majority of my vibration noises start in the rear of the car around the hatch opening. There are two vents (one of each side of the car) in the rear directly in front of your tail lights ... visible when you remove the plastic in the back. They tend to vibrate a lot and you can hear it up front. If the noise is coming from the rear of the car I would check there first.

 

It's definitely coming from the engine bay, and it doesn't always do it (with the A/C on), but 90% of the time when I hear it is at idle w/ A/C on. Grr. Maybe I'll check for something loose; otherwise I'm just taking it in since it has this warranty and all.