Performance/Economy Issues

[BoKo]

Hi everyone, first post and hoping to get some information with more knowledgeable who know our vehicles. I have a 07 Yukon with the LMG 5.3 that recently had the cats stolen after I had a blowout and had to let it stay on the highway overnight. I got a local shop to just weld in some metal tubing and had a 93 octane tune put on it after it kept throwing codes from the missing cats. Now the issue is it burns gas quicker than I can put it in. Before the cats were stolen it was a quarter tank would take two days to burn and now it would just take a nice 20-30 min drive to burn it. It use to beat out my **** Pack in terms of MPG. Now it can't beat a C10 with a clapped out 350. What would you guys recommend I can do to get the fuel economy back to an acceptable level? Any advice, guidance, or info will be greatly appreciated.

 

[NIevo]

Ummmm.....we need a lot more info. Obviously the tune isn't very good if you are running that rich.

 

[BoKo]

Ummmm.....we need a lot more info. Obviously the tune isn't very good if you are running that rich.

Sorry for including everything, what else do I need to include to help give any advice?

 

[NIevo]

What did you do with the O2 sensors that were in the cats, what mods do you have if any, who did the tune, why a 93oct tune if not modded.....etc.

 

[BoKo]

What did you do with the O2 sensors that were in the cats, what mods do you have if any, who did the tune, why a 93oct tune if not modded.....etc.

O2 sensors were tuned out due to the thieves cutting off the portion that had them, no mods, and my father had the 93oct tune thrown on while I was out of town on assignment. It's pretty much a stock Yukon.

 

[NIevo]

Something is obviously off on the tune. Need to find out if it was a generic "canned" tune or a custom tune. Sounds like your A/F ratio's are pretty out of whack. Plus, is there a reason for a 93 tune with no other mods? No reason to have to use 93 otherwise.

 

[BoKo]

Something is obviously off on the tune. Need to find out if it was a generic "canned" tune or a custom tune. Sounds like your A/F ratio's are pretty out of whack. Plus, is there a reason for a 93 tune with no other mods? No reason to have to use 93 otherwise.

Understood and from my understanding it was a custom tune done a performance shop in town and you got me there. I just wanted to have the codes gone and this is what had when I got back. I'll go to the shop myself to see if they can fix and what they messed up.

 

[NIevo]

Yep, I would definitely start with the shop because it sounds like a tuning issue if everything was fine up till that point.

 

[BoKo]

Yep, I would definitely start with the shop because it sounds like a tuning issue if everything was fine up till that point.

Thank you, I appreciate it!

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

You are already receiving sage advice from the knowledgeable folks on this Forum.