06 Solstice (it says "hi!"), manual transmission.
I hear a pretty bad rattling sound when backing up or starting out in 1st gear. I haven't heard it in any other gear, and only at fairly low speed/RPM. (Specifically, when slipping the clutch and reversing up hill, then when starting off in 1st on level ground. (My driveway goes uphill from the house at about a 20-30 degree angle for around 50 feet, then down at the same angle for about 15 feet to get onto the street.)
I have never heard the sound in any other gears, but I haven't tried starting off in 5th, either!)
Update: Here's a recording of the sound.
It sounds like the rattle is coming from the front. The engine runs fine at the moment, other than some hesitation when going WOT.
I have a CEL that's for "System too lean (bank 1)" and occasionally a "Check Gas Cap" message on the unfortunately-named DIC. I think is related to the EVAP system as I also can't put more than a gallon or so of fuel before the pump shuts off. I need to pull the trunk liner and blow out the canister-to-tank line, hopefully that will correct THAT issue.
I initially thought this was clutch chatter - I have a Spec stage 2 clutch and a Spec aluminum flywheel, though i've had those for a long time and haven't heard this noise until recently - but it happens even after I've release the clutch, at least briefly. That is, heavy rain while driving, not helped by the fact that the car is lowered 1.5".
Suggestions on where to start looking?
And I started getting a squeal yesterday - probably the serpentine belt. It's a bit embarrassing when dropping off kid #1 at elementary school. Temps have dropped to mid-30s (Fahrenheit) here in Dallas. I'm not sure why that makes things break but, hey, it's a party.
Thanks for your time.
Also, I can probably record the sound tomorrow and post a WAV or something if that would help?
More information that might be relevant:
Bad hesitation a moment after going WOT. This car has an aftermarket turbo, and this happens when the boost is really starting to kick in. I suspect ECU confusion with regard to boost and VVT. Somehow, I miss carbs. And not the delicious chocolate/bread/cheesecake/Snapple variety, though i also miss those. sniff
Can't fill gas tank in one go (EVAP line, replacing solenoid didn't fix it.) Putting 5 gallons in - I get frustrated and give up after that - requires stopping and removing the nozzle 7-10 times and waiting for the line to clear.
Weird rubbing sound from the back when backing up and turning hard (though not at full steering lock.) I'd suspect a wheel bearing. However, as far as I can tell, there's no play in the hub.
Every few weeks, the coolant sensor reading on the DIC (ha) blanks, going to "---" instead of an actual number. The sensor itself looks fine, and it always come back after a few hours or a day.
I drove this thing in the rain many times with the front wheel well liners removed. This left the ECU exposed to heavy rain on at least three occasions. (The ECU is located directly behind the left front wheel.) BUT, the ECU is a monolithic exemplary example of solid-state, rad-hardened engineering, so I doubt that it's bad.
Here's a recording of the sound when backing up in the driveway. It gets pretty bad after a few seconds. iPhone recording, so not the greatest audio. First one starts at about 6 seconds when I starting backing up the driveway. Then, I rolled it back down to the front of the driveway - clutch disengaged, and backed up again (around 20 seconds in) and the rattle is audible again.
So, at least I can now hear the sound without moving the car. It sounds like something is hitting plastic. The only plastic/composite thing in that area of significance is the intake manifold. I removed and inspected the intake manifold over the weekend - it's only 5 bolts, 2 nuts and moving some intake piping out of the way - and it looked fine.
I'm going to go ahead and drain the oil and have a look. I think the shop overfilled it by a LOT.