E85 issues? 07 Tahoe z71

[Austin Schmidt]

Hello, New to the forum had a topic i wanted to see if anyone would chime in on.
I purchased my 07 Tahoe z71 flex fuel with AFM etc has about 140k miles. Had no known issues when i bought it. Only thing i did was change plugs and wires along with the oil.
SO about 2 weeks later i start using E85 and the trouble comes...
So the first fill up i throw cat codes p0420 p0430, then p0430 erased and only p0420 comes back. On the next fill up with E85 it goes crazy starts throwing the "service stabilitrak" dash board lit up like a Christmas tree, Hard shifts, etc. So i started by replacing the battery since it was so old and did nothing. Ran the truck out of e85 and filled it with 93 plus a techron cleaner and it went back to normal!! So im still stuck with the p0420 and my cats seem to be failing (heavy fumes). None of this happened before e85 use and all times there was hardly any unleaded in tank when filling up. Dealership confirmed that my VIN number was not included in the e85 update issue. Now I'm leaning towards new cats at this point, any suggestions for replacements?

 

[stephygee]

I had the same issue when I tried E85 on my 07 Avalanche. Ended up having to get the AV towed (yep, it died) to the dealership, and they had to replace my fuel pump. Truck performed great with E85, but I don't think the fuel system was used to going back and forth between E85 and 93 octane (I've only filled up with 93..never anything lower). Good luck.

 

[swathdiver]

Hello, New to the forum had a topic i wanted to see if anyone would chime in on.
I purchased my 07 Tahoe z71 flex fuel with AFM etc has about 140k miles. Had no known issues when i bought it. Only thing i did was change plugs and wires along with the oil.
SO about 2 weeks later i start using E85 and the trouble comes...
So the first fill up i throw cat codes p0420 p0430, then p0430 erased and only p0420 comes back. On the next fill up with E85 it goes crazy starts throwing the "service stabilitrak" dash board lit up like a Christmas tree, Hard shifts, etc. So i started by replacing the battery since it was so old and did nothing. Ran the truck out of e85 and filled it with 93 plus a techron cleaner and it went back to normal!! So im still stuck with the p0420 and my cats seem to be failing (heavy fumes). None of this happened before e85 use and all times there was hardly any unleaded in tank when filling up. Dealership confirmed that my VIN number was not included in the e85 update issue. Now I'm leaning towards new cats at this point, any suggestions for replacements?

Did you replace the cats? Seems E85 has a way of flushing out/exposing weak cats.