Sustantial MPG loss

SmokeShank · March 15, 2017

Hey guys,

I have been experiencing substantial fuel mileage loss recently. I have a 2015 Sierra 1500 SLE 4x4 with the 5.3 Max trailer package. It has 8k miles currently.

I am not new to vehicles or fuel concerns. I am a Master technician of over 10 years in the European market.

Symptoms and background:

3 Weeks ago noticed truck sounded more "tickish" at idle than normal. I under stand how DI and HPFP operate but I can truly attest the ticking was louder than normal. I chucked it up to just a harder cold start. I then proceeded to drive truck as normal and found my mileage (typical tank average of 16mpg) has dropped to 9.5mpg. The truck seemed sluggish and while at 50mph in "v4" I found 14-15mpg when I typically see ~23.

I figured I got a round of bad gas from the local station. I drove the trunks tank down and filled with premium from another station. I am still seeing 9-10mpg average which is 50% of what I normally get. I feel like after running a second tank of fuel I should have seen a correction by now if it was indeed bad gas.

I haven't made an appointment yet to have GMC look at it. I was going to see if anyone else has had a substantial fuel consumption loss or not. Original concern as maybe an issue with the AFM.

Thanks for any input

GMCustomerService · March 15, 2017

Hello SmokeShank,

There’s nothing worse than bad gas. If this concern persists and you’d like to visit your dealer, feel free to send us a private message. We’d be more than happy to provide an additional layer of assistance.

Regards,

Anthony

GM Customer Care

Heavy 5.7 · March 15, 2017

Capture live data and see what the O2 sensors are doing.

calgator73 · March 17, 2017

Outside temp?

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2strokesmoke · March 17, 2017

Hello SmokeShank,

There’s nothing worse than bad gas. If this concern persists and you’d like to visit your dealer, feel free to send us a private message. We’d be more than happy to provide an additional layer of assistance.

Regards,

Anthony

GM Customer Care

I know customer service is here to offer up help, but the help people need here is a fix to these problems.

You being a cutomer service rep with a direct open communication avenue to GM should be forwarding these concerns to Head office and their R&D department.

People are tired of being played around with! Owners don't need anyone to hold their hands and make appointments for them, they need answers and real fixes. Corporate GM needs to know about these issues, maybe you could use your customer services skills more effeintly by forwarding each owners concern to head office. This may be a cost thing, to fix these vibrations, however without us, the owners you don't exist!

Thxs