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Hi all. New forum poster with a question (which may or may not have been addressed prior).

Are we all familiar with the start-up sound that the 2007, two-door sedan car makes, after sitting a certain amount of time (at least 45 minutes or more; never made if it was sitting for half an hour-35 minutes or less)? It's done it in all seasons, so it's not related to cold weather or anything. However, yesterday, I noticed that when it went to make the sound, it starts to, but then cuts off- and then the Check Engine light was on (steady, not blinking).

First- does anyone know why this particular model makes this start-up sound? (when other cars do not) I never thought to ask in the five years I've owned it. :amuse: And, secondly, does it sound like a minor or major issue? Haven't noticed any difference in fuel economy or anything like that.

Also- while here- anyone else experience this: getting on the highway, getting to 50mph or more, and the car sounding like it's "pushing"? Not struggling to get there, just more of a sound like it's pushing on- I know engines rev up when you gain in speed, but I don't recall hearing that until some months back.

Thanks in advance for any info/feedback. :)
 

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What your hearing in the startup sound is the actual starter solenoid engaging, plus we use Coil on Plug type ignition with hall effect sensor for the CKP and CMP sensors. Every manufacturer has their unique sound in cranking the motor. Gm uses this combination to give their own sound. Look at Hondas, they sound like birds having a heart attack when starting up.

I don't know exactly what model, but Coby7 would be your best source in asking, he's a whiz at these cobalts :) If your CEL is on which it should turn off after the vehicle has turned over for a few seconds. Its checking all of the sensors/actuators/modules, we call it networking.
 

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In 2007 GM changed the timing chain guide and guard because part of one of the guides of the 05-06 had a tendancy to break. It changed again in 08. This particular year always made noise at start-up like you mention. Once the oil drains back from the top of the engine. Contrary to popular beliefs it is not the timing chain that is rattling but the balance shaft chain. Timing chain has a spring tensionner oil dampened, but the other chain has a hydraulic tensionner that needs a few seconds to prime and build pressure. I have found that by keeping oil at fill mark or slightly over minimizes this noise, that and synthetic oil changed at regular intervals. Also found that parking at different grades would greatly increase the possibility of this noise at start-up. Apparently it is not cause for alarm because no damage is done by this rubbing of the chain on the guard. Just annoying as hell.

For you check engine light, it is probably not related, get the code read and write it down if you get it cleared and come back here and we'll help you fight the beast.
 

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Discussion Starter #4
Thanks for the responses. The noise isn't so much a rattling- maybe more of a buzzing, if that makes sense. But, probably one and the same. :) Maybe it's just a coincidence that the light came on exactly as that start-up noise started getting cut off?

I will return with info after I'm able to get it checked out. Thanks again.
 
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