I recently purchased a 08 SS with 99K miles. The motor seems a little rough at idle. I'm not sure if this is normal since this is the first 4cyl I have owned.

Car seems to drive OK and I'm averaging about 26 mpg on my work commute, 35 miles each way mostly highway.

I also have a ticking noise that seems to come from the front drivers side of the engine. On start up it's about 4 or 5 per second then after about a minute it drops to about 1 per second at idle. It does change with RPM. I don't hear it in the car only with the hood open.

Any insight would be appreciated.

 

The ticking is likely the mechanical fuel pump, normal.

Carbon build up on the intake valves will eventually cause loss of compression and misfires.

 

Rough idle could be spark plugs, at your mileage they are due for replacement AC Delco Iridium 41-108 , do not try to gap them, that little whisker can break off.

 

Rough idle could be something dragging down the idle speed. AC compressor or tensioner.

 

A loose timing chain can cause rough idle!

 

Or even a dirty air filter. I chased a P0101 for a little while, new filter fixed it. But it ran good until the code was set or even pending.

 

Thank you for all the feedback.
I replaced the air cleaner last weekend and today I SeaFoamed the engine and then replaced the spark plugs and coils.
She seems to run a bit smoother now and I also noticed she's idling a bit higher before about 700 rpm now about 900,
I'll see how she runs this week. Hopefully all is well now

Thanks
Craig

 

Hope, I’d take the valve cover off to be sure the timing chain wasn’t stretched , they last 80,000 to 150,000 miles with proper maintenance, but the front guide can give out earlier then that, the upper bolt gets chewed up and spit out.



Even slack like this is enough to bust up the front guide and cause it to idle rough.