I have a some questions for my 07 cobalt with the 2.2 L engine and auto tranny.
1. Right when I start the car up I get a few knocks sounds like its coming from the engine compartment. Anyone else notice anything like that? Wondering what it could be.

2. I am only getting about 22 mpg as shown on the display. Have yet to calculate the mpg after filling up the tank.

3. How can I check the engine vacuum? Where can I hook the vacuum guage on the engine? Any pics?

 

For #2... it all depends on your driving habits.. do you floor it (drive faster than your supposed to)? i drive normally, following the speed limit and i get nearly 26-29 mpg in the city.. and about 31ish on the freeway depending on how fast i go.

and sorry, cant help with the other questions.


btw, i have an 07 2.2 4dr sedan.

 

Some time that knocking noise is caused because there is no oil pressure on start up and goes away the instant the oil pressure comes up.(Oil has drained back and takes a few seconds to get back up to the top of the motor.)
If you use thicker oil in cold weather this will be more noticable.