CEL on.. Bad Fuel Mixture.. What else to try ?
Hello, I've had my GTO for a couple of months now ('05 m6) and recently drove it from PA to CA and ran into a snowstorm near Reno. I had to put on chains and drive roughly for about 30 miles. After I removed my chains, I noticed a CEL and the car shakes when idling and when I put it in gear and try to drive, but when it gains speed, it's fine.
Today, my mechanics and I tried just about everything we knew of. Our computer says the mixture is bad (Low fuel in the ratio). We changed the fuel pump, problem persists, then we changed the spark plugs (reused the wires), problem persists.. we even changed that sensor by the LS2 sign (sorry, forgot what it's called) and it was fine after that for a little while, but the CEL went on again and shakes started. Also, not all of fuel gets burned, due to low fuel ratio (only when CEL is on)..We also cleaned the maf sensor. But it's a low mileage car (22K)
I should also mention when we erase the code, the car works fine, but when the CEL goes on after driving for a little while - the car shakes again at idle and take off.
You can continue this cycle of erasing the code, and it will go back to working fine, and after a while it still screws up. Also, the previous owner had headers installed and a tune was probably done properly judging by me driving it for so long without a problem.
I'm leaning towards a computer problem, rather than a physical problem. But it's a point when I am personally clueless what else to try.
Sorry for the long read, but this is one of those unique GTO problems that we don't know of and never seen in other cars, and need assistance from fellow owners. We have all the equipment and any advices can be tried right away.
Thanks in advance.