About a week ago, I got the infamous P0420 code and have been meaning to change the cat, but haven't gotten the chance the past few days. Regardless, I decided to fill the tank up with E85 yesterday (regular unleaded here is around $3.65/Gal whereas E85 is $3.03) and after roughly 20 min of driving, my P0420 code went away and the feeling of backpressure that was there (preventing me from speeding lol) is now gone.

Question is: does E85 burn that differently??? I mean, it burns at a higher temp because of the ethanol.. but other than that? I just found it interesting that it burns differently enough that it can pass through the cat with ease, where regular gasoline just builds up pressure..

 

Ethanol is a clean fuel. Whenever you burn ethanol in your engine, you're also cleaning everything that the ethanol goes through. If your O2 sensor was dirty, it COULD have cleaned it (although I would be a little surprised by that).

I highly recommend running ethanol in vehicles as long as your PCM is ready for it. It's a great high octane fuel.

 

Sorry- really off topics here:

Indiana I assume? Are you going to Purdue? MET grad '08 here- woot!

 

Yessir, second year of ME. haha I knew some other Purdue people had good taste in cars

 

Ive been running E85 lately, actually every fill up for the past 2 months... Im not quite sure if i can see a difference in performance, i mean i havnt tested the gains in any way. I actually did switch to E85 in attempt to cure a problem that i thought could be my cat, but it did not work/help. Im just curies too what should be expected from E85? is it going to help our cars live a little longer or something lol?

 

Like he said ^, ethanol is clean-burning and high octane. So, even though E85 isn't pure ethanol, it's a higher octane fuel than just plain gasoline. It gives a quicker combustion in the engine (hence lower gas mileage), but it does offer a slight boost in pick-up.
Since it's clean burning though, it doesn't leave as much carbon in the engine so obviously the engine stays cleaner and supposedly has a longer life span.

 

I'm a little car dumb but have a comment/question about this. Is E85 ok to put in my car? 03' monte ss.... stock

 

ains3614, no. Your car is not "flex-fuel".

 

thanks

 

You can make a 3800 capable of running E85 though. It would take larger injectors, a flex fuel fuel filter (I believe from a flex fuel 2004 Chevy Tahoe would work), and a tune. Then you would be all set.