i have a 1997 tacoma 2.7 4x4 5sp. my problem is that i am getting bad gas millage, 110 miles at half a tank, i have 33x10.50 km2, so i know that will affect the millage, but i think it should be better than that. well yesterday the CEL came on and i went to 2 different auto parts stores and they pulled a p0171 code, which is odd, because i can smell gas sometimes when i get on it, like pure gas smell outside the truck, well i took it to a guy that has a better scanner that you can look at more stuff and run tests and all that stuff, he pulled the same code and went looking and found that my long term fuel something was almost 20% it was like 19.53% and he said that was high, and he couldn't get a read on the short term fuel thing, i put in a bottle of lucas fuel treatment with remaining half tank and drove the ˟˟˟˟ out of it after i left the parts store, and again drove it hard after i left the last guy with the better scanner, did seem to drive a little better and no CEL return (he cleared it after he read it) but my question is what could be the cause of this, and has anyone had this happen to them? a p0171 code with a rich smell???? anyways I'm pretty sure theres no vacuum leaks (major) cause theres no hissing sound comming from engine and it idles great and consistent. and the MAF seems to be fine, nice and clean looking, he said to spray the MAF with brake cleaner and also to use that to check for vacuum leaks. so anyways please give me some input on what it could be, i know stuff like 02 sensors and stuff like that, but i don't want to start throwing money at it and not fix anything, thanks guys

 

i have that same problem but my truck hasnt thrown a code mine is a 95 22re 30in tires and im getting 17 which is a load of BS not near as bad as yours though (roughly 8 mpg?)

 

Any remedies? Any fuel smell? Lol any ideas?

 

Please do not clean MAF with brake cleaner. Use MAF cleaner.

When was the last tune up? plugs, wires etc?

 

An unlit propane torch is the best for finding vacuum leaks.

No mess. Brake cleaner is nasty stuff. Use it to clean rotors after a brake job. Thats it.

 

Ok, ill be sure to do that, thanks, the plugs are about and wires are about a month old, haven't ohmed them but they seem fine and no misfire code, coils are prob original if I had to guess, but again no firing codes, just the one

 

i do have a smell of fuel but no real remidies
well i thought it was a clogged air filter but thats not it because with me being a cheap a** (no flaming its back in now) i took it out and ran for a few days and it went up 1mpg maybe more i took it to the local saturday night "drag strip" busy street, i was not nice on the pedal.
i think my truck has 4.56 gears according to gear ratio calcs but i think that would help milage as long as i stayed off the highway with 30in tires (i get bad highway milage)
and dont think its just the fact that im 17 for the most part i drive like a grandma till i get to 5-10 over the speed limit that way i keep good rpms in 5th and still make good time and better milage, just have to be paying real good attention for the police (gotta say it with slow gangsta voice)

 

How many miles on this Taco?

 

yea i dunno, I've owned a fair amount of toyotas, actually thats all i have ever owned and for the last 12 years I've been driving,and all i will ever own, I've never had a CEL come on, and I've done some stupid ˟˟˟˟ to them, and now its bugging me cause i know theres something wrong, but like i said I'm not trying to through money at it, but i want it fixed..... and i want it fixed now, i really like this truck, lol this one is actually pretty nice! but appreciate all the comments and help so far guys, keep 'em commin

 

i heard that sometimes the o2 can get clogged but wont throw a code so you can take it out and carb clean, wire brush, ect and put it back in and wallah practically new

 

theres 190k

 

yea, the guy told me that the MAF can go bad and not throw a code sometimes, and he says he's seen it a few times, i don't know if he meant in general or toyotas only or what, he's pretty knowledgeable thought so i believe most of what he says

 

I say clean the maf...wth maf cleaner..and remove and test the front o2 sensor's resistance.

 

I'm just concerned about the long term fuel and short term fuel reading on the diagnostic machine he had, as far as the long term being "too high" and no reading on the short term, any one know anything about this? he said to come back tomorrow and well drive it down the road and hook some thing up to it and see if we can git it to "fault" ?

 

as far as removing the o2 sensor, he can get a live reading through his machine and said it was fine

 

the guy with the scanner is a moron.

p0171 is a lean code.


you trucks ecu is getting a bad reading from maf or 02. Its saying...i dont like this crap so im gonna run in gimp mode and dump a bunch of fuel in to be safe.

You need not worry about fuel trim or any of that. you cant change the tune on the factory ecu.

Fix why its in gimp mode.

 

P0171 means system too lean and fuel smell sounds like a fuel leak to me. Trace your fuel lines, top of the tank, fuel rail, injectors and manifold gasket.

 

The fella and I both recognized its a lean code, but I can smell gas, that's why I'm puzzled, also he cleared the code so what do you recommend as far as fixing it while the CEL is off, and I understand that the motor thinks is running lean and dumps more fuel to compensate

 

The fuel trim is high due to the lean condition. Once you find the issue disconnect the battery to reset the trims.

 

If your ecu cant get a reading from o2....it will run in open loop. Period.
Open loop will run very rich. Thus the gas smell.

This is really a no brainer guys.