Gas milage dropped to 13.5 hwy? any ideas no lights on

[Dannny B]

My 05 V8 AWD 4-Runner gas mileage dropped by 4 mpg hwy, no lights on but a kind of whirring sound when decelerating has anyone heard of this issue I'm thinking something with the transmission I do get the annoying bang after stopping
Thanks for any info

 

[ebg18t]

A lot of times Whirling = wheel bearings

When was the last time you lubed the driveshaft? A lot if drivetrain clunks are related to unlubed driveshafts..


How dirty is your air filter? I was noticing reduced MPG recently on my truck. I checked the air filter and was uber dirt (couple spots caked with crap). I was amazed how bad it was after 10k miles. I replaced it and noticed an immediate improvement. I have never noticed my air filter that dirty after 10k miles.

 

[2StepsAhead]

My 05 V8 AWD 4-Runner gas mileage dropped by 4 mpg hwy, no lights on but a kind of whirring sound when decelerating has anyone heard of this issue I'm thinking something with the transmission I do get the annoying bang after stopping
Thanks for any info

Get a digital thermometer for like $10-20 or try to use brake dust as a monitor to see if the brakes are dragging.

 

[Atlanta_man]

that's a lot of change

fuel leak ?

 

[gm350reratliff]

I'd check for a brake or two dragging, wheel bearings since you mentioned the whirring noise, tire pressures, suspension alignment, is the engine warming up completely ( thermostat), plugged catalytic converter(s), bad gas.

 

[V8Man]

Like the others said. In addition.
If you gas mileage is a one tank drop could be bad fuel too. Change stations thier meters can be way off.
Look to see if you have the inboard lower pistons stuck on the front cailipers.