Poor gas economy and some knocking...

[txturbogs]

I have a 2014 GT500 with 12000 miles. Just recently the car started to get extremely poor gas mileage and I heard it knocking. Took it to the dealership and nothing.

The car seems to run fine at first, but after it warms up it feels very slugish.

I've replaced the fuel filter, air filter, oil and O2 sensors so far. None of which has helped.

It is consuming tons of gasoline, but the A/F gauge reads as normal.

 

[PhoenixM3]

Bad gas? Did you pull the plugs to see if they have that nice "cocoa look" and appear the same? You replaced all O2 sensors, correct? Good gas mileage isn't this car's thing - how poor are you talking?

 

[Snoopy49]

Check and make sure the supercharger intercooler pump is plugged in and operating.

 

[VNMOUS1]

No kidding. Seen a few that weren't clipped in.

bj

 

[07 Black Beauty]

It's a Shelby not a Prius.

 

[PhoenixM3]

It's a Shelby not a Prius.

What he's saying is that it runs like hell when warm. We all know the MPG sucks, but don't care....

 

[Blk04L]

What he's saying is that it runs like hell when warm. We all know the MPG sucks, but don't care....

Yup. No one buys a Shelby to save gas, but if the drop in MPG went from 15 to 10, for example, with no changes in driving style, it's a cause for some concern

 

[DaveJP]

Did you check the intake/throttle body for signs of oil?...That would also cause what you are describing.

 

[PhoenixM3]

Yup. No one buys a Shelby to save gas, but if the drop in MPG went from 15 to 10, for example, with no changes in driving style, it's a cause for some concern

Right.

 

[blitz1029]

Even if it's stock I would get oil separators