2011 TACOMA GETTING 10MPG!! please help

Saw not long ago, that a member replaced all of his idler pulleys, due to noise. His gas mileage had an immediate improvement.

Tire are good on air, per your posts.

Have you checked all of your vacuum hoses' ends? With the age, they probably have some splits.

The Aussie friends of mine, came across the knowledge that the injectors, (life dependant) were no longer flowing as they should. Reducing mileage. Typically after years of ownership. They replaced them, and found that the more precisely performing injectors (aside from spray pattern) were giving them mpg increases.

Parasitic losses, vacuum hose ends, and injectors(since running rich), are my thoughts. Should the MAF be just fine.

 

I still haven't seen mention of checking your brakes. After your next drive, put your hand on each wheel near the hub and see if any particular wheel is hotter than the others. Calipers sticking is very common. The hot wheel will be your culprit.

 

Just checked them with a temp gun. both were almost the same and not that hot.

 

No, I haven't checked the vacuum hoses... don't know what they are either but ill google it

 

Well, at least is ruled out

 

Son of a B. That's considerably high all things considered. That would explain the drop in economy.

20% fuel trims +- is when our trucks will start tripping codes.

In order to check your MAF (it's not it) you will have to check numbers at idle which is usually around .5-.6 grams/ second and at wide open throttle you should see an absolute/ calculated load of higher than 85%. Most MAF failures usually trip off fuel trim numbers between +20-30%.

I'm going to recommend you check for vacuum leaks using a smoke tester.

It would be a good idea to take a look at the AFR sensors as well, both upstream. 86K is not a ton of miles but you are around the low spectrum of when they could start to fail so they are worth checking absolutely.

Based on what you are describing you should check the fuel pressure, especially since both banks are being affected. If you are under spec of 41.7 - 42 psi you will be running lean.

Fuel injector failure is not common but a possibility. There is always a chance that one could be causing the other to fail as well. The first thing to do before anything is to check the pressure. If it is low, replace the pump, reset the fuel trims and drive it. If all is well then you are good to go, if the issue persists in spikes, then it is very possible you have an injector issue as well.

I have seen both fail in a domino sort of effect. Check this stuff out, let us know what happens. Your persistence and ability to reply back will be key in solving your issue.

 

I’ll look up some videos on how to check those… and run to Harbor freight and get a fuel pressure tester and let you know.

 

Check your spark plugs again. If your running rich you'll know by looking at them (black oily)

 

They are not incorrect if a reputable plug manufacturer lists an iridium plug for your truck in their catalog. I'm on my second set for my 07 Taco with 195K; change them at 100K (1st set were NGK; now have Denso). I have 265 70 17 tires; long bed; 4X4; about 200lbs of equipment/gear in the bed and, can still get 16-18mpg on the highway with AC on (not downhill) cruising at 70mph. I've got 18-20 cruising at 60 on my trips to Ensenada, BC.

Your long term trim readings do appear to be too high. Mine are in the 3-5% range. As was mentioned earlier, a code will only appear in the 20+% range. But, anything past 10 should raise a red flag. Negative reading indicates a rich mixture.

Some common causes:
Leaky fuel injector
Excessive fuel pressure due to bad fuel pressure regulator or restricted fuel return line
Extremely dirty air filter or restrictions in air intake system
Exhaust restrictions (clogged converter, crushed exhaust pipe or plugged muffler)
Bad O2 sensor (output shorted to voltage so it reads RICH all the time)
From https://www.aa1car.com/library/what_is_fuel_trim.htm

Good luck, I hope you find the cause and report back.

 

This is close to what I used to get as well. I'll give these all a good look as quickly as I can and keep everyone updated. Money is tight right now and I have very limited resources, so that's also an issue but I'm doing what I can with what I got.

Again thank you everyone for the help!

 

Oh hold on. I just re-read the issue. You have negative fuel trims, not positive like I originally thought you did, correct?

 

Correct. They are both negitive.

 

In that case, the list given to you above will be a good starting point. MAF is still a possibility but you should take inspection priority on the items which controls fuel delivery for both banks.

As always, you should inspect both air fuel sensor for good activity and make sure they are responding pretty quickly.

 

following

 

sounds like U bought the taco u s e d ........

NO telling what the prev owner did.................or did not do

attempt to determine the differential ratios.................U might have some stump pulling gearing

an OBD scanner should be throwing U some codes

 

Subscribed. Exact same truck except my mileage is at 140k. I’m filling up every 200 miles.

 

Funny timing on this thread. I just returned from my second road trip this year and for 4 straight tanks, my average dropped to 12.5-13.5 for no reason at all. With a couple thousand miles on my trip, filling up with a max of 200 miles every time wasn't promising. I typically average 15.5-16.5 (all uncorrected for tire size). I think my last fill is getting back to closer to normal, but I returned home w/ 1/2 that tank.

On the road I checked for vacuum leaks, tire pressure, etc. No codes on scangauge. I noticed scangauge doesnt report Fuel Pressure on our trucks? I never looked at it previously.

Even on prior winter gas, I'd never see 13mpg avg. So something was/is definitely going on. My initial thoughts were an o2 going bad, but wouldn’t that throw a code?

 

I would check the fuel pressure regulator, so disconnect the hose between the regulator and manifold at the manifold and cap the manifold. Now run the engine and see if you have any fuel coming out the hose from the regulator it should be 100% dry if you have any fuel present in the hose the regulator is bad.

 

Update, I’ve now gone through two different oil changes. Changed transmission oil, rear diff oil, front diff oil and transfer case oil. And put a shell on my back. And with all that I seem to be getting about 16 now which is not too bad for 33‘s. What ever you do, DO NOT get a Pedal Commander