seanm243

Hi forum,
I've been getting some exceptionally bad gas mileage lately. A few weeks ago, i was getting 15-17 MPG. It started dropping after that and I just finished a 430 mile drive where I got 12.5 MPG the whole way. Now, I understand I drive a truck but, what the heck? that seems pretty low. Have any of you guys experienced this? Around town, I'm now getting around 10 mpg.
Thanks,
Sean

Tothemax

When was the last time you checked your air filter? Changed your oil? Spark plugs? What octane fuel do you use? Have you done anything to the truck lately?

seanm243

Air filter didn't look too bad a few weeks ago but I'll look. Oil was changed 2,500 miles ago, used shell 87 octane, and put on a 3.5" catback, boost bars, and raptor grill lights. I don't think any of those would hurt gas mileage. Maybe I need to invest in a CAI and tuner?

JLTD

SOMEthing has changed. Did the drop happen after the recently installed goodies?

O2 sensors failing in the rich position (or the engine not leaving the closed loop warmup state) can cause bad mileage - check the inside of your tailpipe once it's warmed up and see if it is wet and/or smells like gas.

What has your mileage dropped from?

seanm243

Mileage has dropped from around 16. Tailpipe doesn't smell like gas. It actually happend slowly from the 95,000 mile service when I had my coils and plugs changed. I'm gonna go look at a few things now and maybe replace the air filter. When I was driving last night, Something felt odd, almost like it was pulsating when I slowed down for a light. Could it be possible that I have a stuck brake?

seanm243

Just replaced the stock air filter with a K&N.

Ricktwuhk

I track my mileage tank by tank, and record it. Any big drop I immediately notice. If I was going to change things (as you did), I'd fill up first, reset MPG, and then put on the modifications. IF you did that, and it then dropped, you have your answer.

I cannot imagine that an air filter would cause a significant drop ALL AT ONCE.

seanm243

I've had brake issues with this truck. I've had the exhaust on for almost 3 months now and it hasnt made a difference. I also don't think the boost bars would make a difference. I needed to replace the air filter anyway. I think its got to do with the brakes.

Daniejw

What is your average MPG while cruising with cruise control on at highway speed?
Like 65-70...

seanm243

13 now at 65... used to be around 17