NO. Fuel trim is high cause its in open loop. Lean code more than likely from bad 02.

O2 goes "Bad" starts lying to ecu. ecu gets pissed and tries to drown it with fuel.

 

If it was in open loop it would not even look at the fuel trims or o2 sensors

 

Thats exactley whats happening. Its in open loop.

Takes 10 minutes or less to pop on an o2. At 190k...should get a new one anyways.

But I bet the light goes off...gas smell subsides...and mileage improves.

 

Ok, so upstream o2 sensor?

 

Yes..one on engine side of cat.

Get some maf cleaner while you are at the parts store as well and soak those o2 nuts with some blaster...before you head there..and after.

 

Ok, any idea on costs of o2 sensor?

 

Usually less than 100. get the denso if possible. some people dislike the bosch...but I have had one thats been good to me.

 

I show upstream denso at auotzone for 108.

http://www.autozone.com/autozone/par.../N-j9ia5Z9ixrp

 

I'm seeing them on amazon for about 50 - 60 bosch or denso

 

Good deal if you can wait for one in the mail.

But, if you bought the autozone one...and it wasnt the problem, clean it up..toss it back in the box...and return it.

 

Yea I am do the same with amazon, and and plus I get free two day shipping so it will be here Friday,also are the upstream and downstream the same sensors? I thought I saw so where on this site the the downstream is input or read only or something like that?

 

you want upstream.

 

Right, but if they're the same ill just get two and replace both

 

o2 sensor wouldnt hurt to change so try that anyways. I had the p0171 code for a while and mine ended up being a clogged fuel filter i got a 98 tacoma 2.7 5spd. If its not either then do a good vaccum leak test to make sure you dont got any leaks.

Another thing check to see if your exhaust manifold is cracked that will toss a lean code too. I have gone through 4 exhaust manifolds in 1 year on my truck, bought the cheap autozone one with 1 year warranty and its coming up on a year so im going to buy the mini headers after.

 

update:

i installed a new fuel filter and nothing, actually while i was sitting in the driveway in the car when i got home, i was on the phone with a friend and the CEL came on and it started idling really rough from about 600 - 800 rpm, felt like it was going to die but it never did, replaced the fuel filter and nothing at all,checked to make sure all plugs were secure on wires, going to clean MAF tomorrow,then move to new plugs and wires, then o2 sensor if need be,any opinions on seafoam? I've seen people swear by it, never tried it, not really keen on using that stuff, i kinda feel its like the fix a flat of engines..

 

I was expecting to see the 02 sensor installed and this to be a victory post.

Im usually right.

 

lol i like your enthusiasm hilux, I'm not doubting you any bit, you obviously have more knowledge about this stuff than me, but can a bad 02 cause all this, the p0171 code, the rough idle, gas millage??? i mean like if everything else works great and just the 02 is bad, or could it a 02 and something else?? i don't know what code it threw today, i didn't get it checked, but I'm sure its probably the same one again, thanks again

 

Yes a bad 02 can cause poor gas mileage and a rough idle an 02 sensor is used for fuel management to help make sure your truck runs as efficiently as possible. Most of the time when any vehicle comes in with a 02 code 90% of the time replacing the bad 02 fixes the problem i.e poor gas mileage, rough idle and your CEL. Basically your truck is running like crap because the 02 sensor isnt working thus your air fuel ratio is messed up causing your truck to get poor mileage and idle like garbage.

 

Causes for lean condition. Dirty MAF, clean with MAF cleaner only and let dry on its own. Dirty injectors, seafoam good idea. Fuel delivery, check running fuel pressure then watch it after you turn the engine off to see if it drops. Vacuum leak, get the scan tool you used that had live data with fuel trim if at idle the trim is high then hold it at 3000 rpm and see if the trim drops. Exhaust leak before the o2 sensor.

Do you ever have a long crank after the truck sits a period of time?

Feal free to ask me to elaborate or re explain any of that

 

Ok, well this might sound stupid/crazy/weird, but any possibility it could be a alternator or battery? When ever its idling and I cut my headlights on it drops to about 500 rpm, any chance the electrical is weak and causing not enough spark or maybe not powering the feel pump enough? Therefore getting the lean code, and low rough idle, if I gas it up to about 7-800 rpm it idles like a champ, no juttering or anything, anyways I'm off to the parts store and get the maf cleaner and 02 for upstream update in a little bit, thanks