Sudden poor gas mileage, Toyota Tundra -04

Keep throwing parts at it you'll fix it eventually (and empty your wallet at the same time). Then you can bitch at the mechanic on how he charges too much after the fact. At least, that's how it goes around here.

I think the Autozone down the road sells about 25 gas caps a day on P0440 codes. Customer gets pissed when I say OEM caps only! (it's true though.)

 

Thanks guys, I have been away from home but I'll definitely look into some of the suggestions ...

As for throwing parts at it, I'm not sure how expensive it is for checking for vacuum leaks, binding rotors/drums, cleaning the MAF etc.,

 

Let it idle and spray brake cleaner. If it has leaks idle will change.

 

^^^^ Old school trick my dad taught me. Works every time.

 

Not every time. Let me throw this out. I recenty had a 2008 Honda CR-V come in with the MIL on. Code P0171, running lean. Sprayed everywhere with the Brake Clean with no results. I had the tablet hooked up to the car with the data list on. My fuel trim was 1.47. Some more futzing around and then I tried clamping the power brake vacuum booster hose. The trim dropped down to 1.00. Now there was no indication of the motor running any differently, but the trim kept changing every time I clamped or unclamped the hose. For secondary confirmation I turned the motor off, waited 5 seconds and then stepped on the brake pedal. It was hard as a rock. Normally you should have enough residual vacuum for 2-3 vacuum assisted brake applications. Internal booster leak.

 

You're the one that said you threw oxygen sensors and spark plugs in it. Spark plugs I get, but o2's for the hell of it? Gets pricey, even more so when they are actually air ratio sensors.

 

I took it to a supposedly reputable shop and when found out I had over 200k on the pre-cat O2 sensors, and unknown mileage on the plugs, they told me to swap them out...

 

60% of the time it works every time.

 

Bump! Ive got a 2003 tundra that started getting crap milage out of the blue.Also seems to have an odd shift issue simultaneously with this poor milage. Seems like a slipping clutch but its an automatic. What was the end result with yours?

 

Not the same vehicle, but I had a Ranger with the 3.0 V6 that ingested a bad tank of gas. It hiccuped, then ran poorly enough that I had to floor it to stay at freeway speed for a few seconds. Almost immediately after the engine cleared up the CEL blinked on, and I then had to replace the sensor in the exhaust (the name of it escapes me at the moment). The rest of the tank (and maybe the next one as well?) was horrible mileage with the CEL on, but once I replaced the sensor and cleared the light the MPG issue resolved itself.

 

You'll shift more if the engine is making less power or something is dragging [like a caliper]requiring more power so that along with gas mileage reduction makes sense. Tons of things to cause it like everyone on here has said already so start checking EVERYTHING or take it to an expert who can.

 

Clean your MAF and see if you notice a difference. If it doesn’t help, that doesn’t mean that it’s not bad or it’s not still good. But it’s easy to do and they can cause shifting and fueling problems.

What exactly is odd about the shift? What gear/does it happen in?

 

Spray some on the brakes too

 

Bands is the word you are looking for...

How many miles on it?

 

And a hot exhaust manifold

 

Bands??................150K miles.

 

Make sure the fan clutch isnt stuck, take it to a decent shop and let them put a scanner on it and look for stupid numbers. A ECT out of range will cause a different shift strategy and no lock up, A dirty MAF can cause shift issues but will normally set a check engine light.

Could always be the trans taking a crap also....

 

Once the truck is up to temp, it accelerates from a dead stop fine but after 1st or 2nd gear it hestates to shift and it revs out with very little acceleration. Once im on the highway,if there is even a slight incline,the speed will drop 10-15 mph and it isnt very steep grade most times.. milage has gone from around 20 mpg to 13

 

Yep,was heading to get it scanned today. The CEL did come on now.

 

This was the best 10 bucks I spent in a while.

https://www.amazon.com/Kitbest-Blue...02&sprefix=bluetooth+od&sr=8-4&ref=mp_s_a_1_4