very poor mpg

[iamryan1993]

It's a 2008 Chevy colbalt lt. It's has a 2.2. Auto 4door. With 86k miles. Car is getting 19mpg highway. The dealership last year put in a new fuel pump and all new injectors. In the last month I have changed the spark plugs. I put in acdelcos with no improvement so changed them out for densos. Air filter. New tires. Alignment checked good. Just changed oil. Ran fuel treatment thru it and even 93 octane gas with no luck. I'm planning on doing a valvoline 3 part fuel system kit soon. But what else should I do?

 

[roosterk0031]

How's the tail pipe, when I've had O2 sensors go bad the car defaults rich and get some black soot inside the tail pipe.

How was the spark plug color, tan or black?

What's the rpm at 60 mph is the torque convertor locking up? Should be just over 2,000 I think. My daughters 2010 takes 2-4 miles when cold before it finally locks up.

 

[YelloEye]

You should be running 87, not super important but you're not doing yourself any favors running 93 unless the car has been tuned for it.

Could be that the cat is going, but usually the o2 sensor will show it dying. Any codes?

 

[iamryan1993]

The spark plugs looked tan. And there is no cel. This Saturday I'm going to replace the fuel filter. Clean the maf sensor and the filter in the evap and see what that does. I may go ahead and pull the o2 sensors and clean them up and check the condition. Also off topic I bought a new radio and speakers is there any tips on removeing the window cranks?

 

[roosterk0031]

I watched a youtube video on changing speakers and it showed how to remove the cranks, I didn't pay any attention to it because I was dealing with power windows.

Check your wheel/brake temps after a drive see if one is hotter than the rest. I don't think fuel filter or maf will make any difference.

Steady state 55 mph my 2010 auto easily get 35-40 mpg indicated average flat road once warmed up & AC off. 2010 engine is slightly different but you should be close.

What's your water temperature running? Maybe t'stat stuck open. Both of mine run in the 180's.

 

[YelloEye]

Cranks have a C clip holding them on. A small pick will get them off.