Here is a short of the video. I have another video of a cold start where it does not make the sound. I've started the car several times cold and its never happened. Only after the car has been running for a while.

Car just got back from the tuner and its coming from the drivers side of the engine bay close to the fuse box. Also, car starts rougher during the warm start.

Does anyone have an idea of what this could be? It doesnt sound like a heat shield rattle, and I havent seen anyone else have this problem.

​​​​

 

Only on start up? You don't hear it any other time?

It kind of sounds like a heat shield but a bit heavier than that if that makes sense?
I'd probably start wiggling stuff in the bay and looking for loose bolts.

 

Well, I didn't mention this but the rattle will come back once in a blue moon in a rattle for the same 1-2 sec duration. That's how I knew it was around the fuse box. I waited for about 7-8 minutes with the hood up and only heard it once. So hard to troubleshoot this way.

 

Yea, its hard to say. I'd venture that you have something loose over there.

Stock airbox and everything over there?

 

Nope it's got a CAI with the battery relocated to the trunk. The reason why I don't think it's something loose is that the sound is exactly the sound every time. It suspiciously sounds like a IAC valve but that's not where the sound is coming from. I'll need the wife to crank the car while I look at the engine bay to confirm.

 

I have had a failing IAC, that noise is far too loud. You can't hear the IAC over the engine running.

Yea, having someone else crank it is a good idea. I'd still take the 5 minutes and just try to shake some stuff lol. It is odd if it sounds EXACTLY the same every time though.

 

Just thought I update the thread in case anyone else has the same issue. Found the reason for the rattle. It's the stupid Grimspeed EBC. Only does it on warm start up and occasionally once afterwards. Drove it 30 miles today and only heard it on start up.

 

O interesting. So it was the noise of it cycling that you were hearing?

 

Yeah not sure if its a leak or what, but I feel it pulsating against the side of the frame its bolted on to. I am running a bit rich as well dipping into the 10.7, 10.8 sometimes... so it could all be related.
Anyways after finding out the problem I handed the car back to the tuner. He confirmed it was the EBC.

I'll provide updates soon!

 

That's pretty interesting. It makes sense if the bracket for the solenoid isn't isolated from the frame, it will move as it pulses and cause a rattle.

Glad you found the issue!

 

The EBCS's make a little rattle/ticking noise when bolted to the frame. We put some 1/8" thick rubber under them to dampen the noise out.

 

Didn't know you were still active here, good to see you again. The weird thing is that the sound only comes on during a warm start. Every cold start I do, car cranks awesome. Warm starts is when the engine hesitates a bit and that I hear that sound every time.

Car also runs rich. Definitely a sign of a leak somewhere imo.