I’ve made the determination that it can be kind of hard to find E85 at times as it’s easily in less than 10% of stations. The cobalt isn’t initially a flex fuel car, and I’m assuming there are likely a few important distinctions in the PCM of a car that is designed to be an FFV. The cobalt doesn’t have the ability to tell what sort of fuel is in the tank, and it also doesn’t have a method for automagically changing the programming for it. However, the fuel trims built into the PCM have the ability to compensate for slight differences in fuel types, such as using 100% gasoline, and 10% ethanol gas, or gasohol. This seems to be able to make up enough difference if the AFR is set dead in the middle of E85 and Gasoline.
The unfortunate part is depending on how the car is driven after refuel, I’ve noticed it taking around a quarter tank or more to get the proper fuel trims in the ECM. The only real signs that seem to be exhibited are some hesitation on shifting and acceleration, but I’m sure there are other problems for the actual engine itself that aren’t always perceptible.
I still haven’t gotten the wideband in, nor a solid base tune on a specific fuel set, so I can’t be certain that the problems I’ve been experiencing with it wouldn’t be remedied with that being fixed. It would be nice if I could find some time to get that accomplished.