brandyn85

i thought that body style onle came in automatic?? well the check engine light turned off tuesday on the way to work and it is still off... and its still running good... so for right now im going to leave it... but if it comes back on im going to the dealership to get the A/F sensor

2000t4r

No one has talked about a possible vacumm leak. I have had all of the things that you are talking about. I replaced both the MAF and the A/F (california) and have yet to find a vacumm leak.

MTL_4runner

The P0171 alone could be a vacuum leak, but in Brandyn's case there are multiple codes, all of which look to be pointing to the A/F sensor.

brandyn85

well the check engine light is still off... we are taking it to the beach today(about a 3 hour drive each way) so that will test it i guess... im wondering if maybe resetting the computer with the code reader didnt clear the long term codes and they just ended up cycling through and clearing themselves... but i will be back and let you guys know how she did

MTL_4runner

If the codes are all off, then great......just drive it until you get another CEL and then reread them.

brandyn85

we got back from the beach today, about 350 mile round trip, and no cel. also got about 250 miles to a tank of premium gas. about 3/4 of the time was on the highway.

brandyn85

its back! cel came on lastnight sitting at a stop light... my girlfriend noticed it started to idle real low and looked down and right as she started to go the light popped on... P0171. the obd tester said it was the pending code and the trouble code...

brandyn85

codes still on... trucks runnin like crap, it died twice lastnight, still starts right up tho... is it possible that the a/f sensor i took out originally is still good and the only problem was the MAF sensor? would just the maf sensor trigger the 171? because i checked around and the part stores around here all want at least 400 bucks for the a/f sensor... and i dont really have the money to keep throwing at this truck hoping each thing fixes it..

MTL_4runner

If the only code you have now is P0171, then you could certainly try another MAF (it would be alot cheaper than the A/F sensor to be sure). It has been somewhat confusing what you replaced and what you haven't, what is new and what isn't......lemme recap so myself and others don't have to keep rereading the thread and guessing as to what you did or didn't do so far.

Problem: Still showing a P0171 code....no other OBD codes currently

Replaced thus far:
MAF - cleaned, swapped, never replaced with new OEM?
Front A/F - Replaced with new, what kind was it and where did it come from?
Rear O2 - never replaced?

Have you ever looked for vacuum leaks on the motor yet?
Have you ever looked for exhaust leaks before the front A/F yet?

Please comment next to each.

brandyn85

MAF- replaced with a known good, used one
A/F sensor- replaced with a new O2 sensor, a cheap one from napa...before knowing about the california emissions...
Rear O2 sensor- never replaced

i have checked for vacuum and exhaust leaks.. found nothing

heres a sum of what all happened...

truck had a check engine light for about 6 months... it was hard to start(cranked about twice as long as it should before firing) did that since we got it, then it started to idle rough and would die once in a while but fire right back up, so i decided it was time to fix it. code 171...got the cheap o2 sensor since they have worked on all my other cars. put it in, reset computer, started the truck, it ran kinda rough...i drove it around the block and it seemed to run ok when i got back, it was still hard to start, check engine light came back on... next i replaced the spark plugs, everything stayed the same... then i ran about 3/4 of a can of seafoam through the intake, puffed smoke and did its thing, ran 1 1/4 cans through a full tank of 92 octane gas. it seemed to run a little smoother... gas milage still wasnt lookin too good was barely getting 200 miles on a tank of gas, and thats freeway to and from work everyday. next i replaced the fuel filter and MAF with the known good but used one. reset the computer, started the truck... it fired right up and ran smooth. everything was fine for 3 or 4 days... and the CEL came back on, stayed on for a day or 2, then turned off by itself. and stayed off for about 700 miles, also got about 260 miles on a tank of gas mostly freeway.. then the other night it idled real low at a stop light, and when accelerated the CEL popped on and is still on... last night when i was following my girlfriend, she gassed it and the truck puffed a bunch of black smoke...and when she pulled into the driveway the truck died again, the fired right up again... and thats how it is today...

SpikeStrip

This might help:

MAF DIAGNOSIS LINK


It's a bit technical, but if you're still getting the CEL and you're trying to rule out the MAF, well...


Good luck.

MTL_4runner

Brandyn, even though the P0171 is a code most commonly associated with the MAF sensor going bad, the fact that you replaced the A/F sensor with what is likely just a regular old O2 sensor from Napa and that you tried a MAF from another truck which was presumably good (I assume you did vice versa and tried your MAF in the other truck as well), that my guess is still that the A/F sensor is still your problem (these trucks do not like non-Denso parts, basically go OEM or you're asking for issues and got no CELs). I would order a new sensor from URD and have it sent to you (it's alot cheaper than the local dealer). Then reset the ECU with the neg batt cable. If the code comes back as P0171 then it is the MAF for sure. If you want to kill the problem for sure, order and replace both parts at once.

There are a few places with good prices on those A/F sensors (although they're just under $200 even at the cheapest prices available):
www.urdusa.com ( http://www.urdusa.com/product_info.p...s_id=430006000 )
www.toyotaofdallas.com (PM Phil, strap22 on YT)
www.northridgetoyota.com (Talk to Evan)
www.toyotapartsales.com

The last 3 can also supply the MAF sensor if you need one at much cheaper than $200 so ask about that as well.

brandyn85

i think im going to order that a/f sensor, the check engine turned off again yesterday and its running awesome...

brandyn85

well i decided to put the old A/F sensor back in today to see what would happen, i was changin the oil so i figured it wouldnt hurt.. so far so good...no check engine light, and its running good still... if it comes back on tho im going to order a new one for sure

brandyn85

well still no check engine light... but last week we had some snow here in washington, and my girlfriend slid it into a concrete barrier. body shop said about 4500 in damage, it should be done saturday at the latest

brandyn85

Bigblock

That makes ME cuss outloud.I know you did!

brandyn85

oh yeah i was pretty pissed, i had to change a flat tire in the snow at 7am, it wasnt too bad tho im glad she was alright, the truck went to the body shop the same day and the deductable was 500 so its not too bad

Hoopster

That sucks about the crash but at least she lived. I'm subscribing to this thread since I have the same p0171 code. I've changed the front o2 sensor with a denso and cleaned the MAF. I don't use a K&N filter. There are three things that I think could be causing this other than a bad MAF.
1 Fuel filter
2 o2 sensor after cat
3 vacuum leak.

Anyone care to comment? I have a '99 limited w/145,000 miles and as far as I know it has original o2 sensor (rear) and fuel filter.

My wife claims real sluggish for the first few minutes in the morning which I can sometimes replicate and it won't even pull out into traffic, barely making it up to 25mph so it's quite dangerous.

HELP!

MTL_4runner

Try cleaning the MAF with liberal amounts of brake cleaner (let it thoroughly air dry before starting the truck again) and see how it does (also just because you cleaned it doesn't mean the MAF isn't the problem, sometimes it requires replacement). If that more thorough cleaning fails, next you're looking at needing to try replacing the MAF and O2 (A/F) sensor. I probably change the MAF first then the O2 sensor because the MAF should be the cheaper of the 2 items.