So I've done some math and it turns out I'm getting horrible gas mileage!

About 24 mpg at best! And that is with me driving super easy 90% or so on the highway at 70 mph, the rest 55, thats my normal commute. Not many stops signs or lights.

I have no idea why its so bad...I just replaced my upstream O2, my coils, plugs, and TPS Sensor awhile back because I couldnt find out why my car was jerking on the interstate, turned out to be the TPS sensor. When revving my car up slightly and comming off of the pedal the idle catches itself from dieing and moves up, the lights dim some also. At idle my car is a tad jerky, i think I may have a sticky lifter or something.(see). Also just did the oil with Mobil 1 synthetic 5w30 and K+N filter + restore. Oil filter replaced about 4 oil changes ago. Fuel injector cleaner ran and sea foamed before oil change.

Help?

I bought some super concentrate Techron for my Cobalt and it went up from 30.5 mpg average to 32.4 mpg average.

Also, check the tire pressure, gas cap, vaccuum leak, dirty air filter, fuel filter, any wheel parasitic drag and so on.

The wife's Sunfire has the exact issue as you. Replaced the O2 sensors, Sea Foamed, new oil, plugs, a new axle and hub.
It went up 1 mpg from 25.
I thought it would be much better than this. She gets 26mpg, when she used to get 29.

I also pondered the timing chain. It has around 120k miles on it. It stretches and causes a timing issue, and I pray it does not snap.
It just costs so much for one, and I am always broke.



My wife's 2003 Ecotec 2.2 liter Sunfire:
* 2 1/4 inch in and dual 2 inch out muffler Trans Am muffler
* 2 1/4 piping to a very long 2 1/4 inch resonator
* 2 1/4 inch catalytic converter
* an AEM true cold air intake NOPI edition
* 8 gauge ground wire kit
* Toyz front strut brace
* Russell stainless steel brake lines all around.

Im at 89K, but I will admit I give my car hell for a DD, it sees the full throttle a decent amount.

I was reading it could possibly be a MAP sensor..air filter is clean, fuel filter should still be cleaned, replaced about 15k ago..maybe I should replace it again, tire pressure is fine.

I have a powertrain warranty and am going to try and see what I can get out of it. Vacuum leak im not sure about, i sprayed some brake cleaner back there and didn't hear it rev up, but It doesn't convince me, I want to take the intake apart and look back there to be for sure.

This damn car always has something to discover and fix.

Do you still have the damn IAT resister in? Do you also know that you are suppose to change the oil filter every time you change the oil?

No, temperatures change outside, i try that only at the strip. And yeah I'm not stupid and if you read you would see that I wrote K+N filter.

After reading some stuff im beginning to think it may be MAP or fuel filter. It shakes a little bit at idle when warmed up, not noticeable by RPM gauge though, its like a slight miss or something.

Verocity wrote: And yeah I'm not stupid and if you read you would see that I wrote K+N filter.

Doesnt matter what brand the filter is. It's like putting your dirty close back on after you get out of the shower.

Verocity wrote:Im at 89K, but I will admit I give my car hell for a DD, it sees the full throttle a decent amount.

This.....and winter blend fuel will hurt your fuel economy.

As for the miss, have you replaced your plug wires or made sure they're firmly seated on the coils and plugs?


2.2 97 Cavalier......the "Crapalier"

theyre all the way on the coils for sure, and they're pushed down on the plugs as much as i could get them to, how much of the spark plug should be visible with the wire on it correctly?

I don't think its ignition miss.