Ok I am experiencing an odd issue, I don't think it is FI related, but clutch related. This only happens when cold and within the first quarter mile of driving. I just had a dealer installed upgraded clutch last year.

You know how if you are driving and there is a bouncing rock, or piece of junk in the road and it hits the underside of your car and you just hear a light something-hitting-metal noise underneath the car? Everytime I start the car cold in the morning, I will get a couple shifts and a few hundred yards down the road and on a shift, when I push in the clutch I hear a very light something-hitting-metal clack that sounds like I just ran over a small bouncing rock. Sometimes the noise seems to come from the right side, sometimes from straight underneath, and sometimes the left side. It is never real loud, but I just started noticing it.

Clutch works just fine but it only happens when the car is sat-overnight-cold, within the first few feet, and only when pushing in the clutch. It also seems to only happen once each time you drive. Given that the noise comes out different parts of the car it is almost like it is on something rotating. I generally am easy on the car when it is cold, and ease into first, shift at fairly low rpm. I try not to bring in any boost until three bars, but sometimes I have to turn up a steep hill or scoot into traffic and have to give it a squirt of gas and that seems to be what induces it, any little jaunt above maybe 4000 rpm, clutch and clack noise. Again only once, and only when cold, shift and then "thwack".

Does this bring up any ideas with anybody?

What I am visualizing is that some dohicky is free to wiggle in space (like a brake pad that has boken away from the backing plate but still held in the caliper) and when I back out of the garage it is somehow rotated back in the space it is trapped, and then the first shot of gas throws it forward until it hits the front part of the space it is trapped in. But it seems to be related to pushing in the clutch pedal and makes no sense to me.

 

Well, I had a noise that I thought was clutch related about a month ago...it would only happen at certain rpm's and would go away the minute I pushed in the clutch pedal. It would not do it all the time like yours, but it was more of a jingle...like a bolt had backed out and the washers were "dancing around" on the bolt. I looked and looked and finally I found that it was actually two separate things. the AC compressor mounting bolts had backed out and were loose and the spark plug cover was loose...both jingled.
I know this is not what yours is doing, but just goes to show that sometimes the noise is not what or where you think it might be located.
Good luck!

 

Have you figured out what that is? I am having that same issue. BUT worse. Initially, I noticed the sound only when backing the car. But my stereo was gone for a few days. I start to feel it ever since. Whenever I push it into gear, except first. The wiggling sound comes out. My suspect was transmission mount. But I took it to a mechanic couple days back. He said the sound is more likely from inside the transmission. My backup sensor is gone as well. So my transmission could really be messed up. I have not have the time to leave the car for pin-point what is wrong. So I might need a new transmission or simple as tightening the transmission mount. What was the cause of your sound? Have you figured out?