1. Welcome to Tacoma World!

    You are currently viewing as a guest! To get full-access, you need to register for a FREE account.

    As a registered member, you’ll be able to:
    • Participate in all Tacoma discussion topics
    • Communicate privately with other Tacoma owners from around the world
    • Post your own photos in our Members Gallery
    • Access all special features of the site

P0171 CEL Code

Discussion in '1st Gen. Tacomas' started by Greensystemsgo, Oct 30, 2011.

  1. Oct 30, 2011 at 6:03 PM
    #1
    Greensystemsgo

    Greensystemsgo [OP] Self Proclaimed first gen expert :doh:

    Joined:
    Jun 13, 2011
    Member:
    #58216
    Messages:
    2,843
    Gender:
    Male
    First Name:
    Nick
    Avondale, AZ
    Vehicle:
    1999 TRD/SR5 4x4
    5100/5125's All pro expedition leafs Eibach coils Light racing uca's 2004 gauge cluster All stainless brake lines 1" diff drop kenwood with polks rebuild seat support webbing satoshi grill optima red top
    Normally at half a tank im at 150 miles, now though at half a tank I was at 80, and at 1/3rd left, im at 130.

    The CEL came on during hard acceleration up a hill. Sense this issue happened three weeks ago i discovered that my most rear exhaust hanger had come undone. Possible that the cat sensor wires snapped and is screwing my fuel efficiency?

    Autozone tells me Fuel mixture system lean bank 1.

    Ive had this issue on bank 2, and it turned out to be the coil, they're all stock, at 182k miles now.

    Truck is still powerful, but at idle has a light chug, and during hard acceleration shudders a bit.

    Causes Low fuel pressure, (pump/filter/blockage? I'd imagine id have a loss of power?)
    Faulty MAF/VAF sensor (its stock and clean)
    Cylinder misfire condition (this doesnt say a whole lot, coil?
    Faulty HO2/AF sensor (is this the cat sensor?)
    Large vacuum leak (ill spray starter/brake fluid, but doubt its this. i have all newish hoses.)

    Also, this info is from autozone, when my parents had a cel on their 98 GMC, the dealer told them it happend a certain number of miles ago, which they calculated to a hill, it was a misfire and happened once and that was it. so the dealer reset the computer and theyve had no problems sense. Can a toyota dealer tell me anything more? Sure would be nice, autozones info seems.... universal and leaving some to be desired.
     
  2. Oct 30, 2011 at 6:58 PM
    #2
    SCSPerformance

    SCSPerformance Stealth Custom Series™

    Joined:
    May 25, 2011
    Member:
    #57195
    Messages:
    3,248
    Gender:
    Male
    First Name:
    Vin
    Bay Area, CA
    Vehicle:
    2005 Tacoma
    Camburg LT kit DMZ SUA kit SCS wheels Matte Black custom paint
    it's running lean so the computer is compensating the lean by dumping a lot of fuel thus your poor gas mileage. i know you said your maf is clean, but did you actually clean it or did it just look clean? do the usual tune up parts as well. it could be the a/f ratio sensor which is common to go out on these toyotas. you have a good list going so just start with the cheapest and easiest things first.
     
  3. Oct 30, 2011 at 8:15 PM
    #3
    UndefinedTaco

    UndefinedTaco I'll eat all your food.

    Joined:
    Jul 4, 2011
    Member:
    #59313
    Messages:
    2,036
    Gender:
    Male
    First Name:
    Justin
    Tracy, CA
    Vehicle:
    Toyota
    It's an 89 Toyota Pickup. I got some stuff done to it.. FJ axles going under it soon.
    It could be your upstream O2 sensor, but doubt it.

    PO171 is a common code for misfire, it's most likely a misfire.

    I'd bet it's something far as spark. Coils, wires, or plugs.



    You can try and resetting computer..pull NEG terminal on battery for 15-30 minutes.
    Then put it back on..then start it, pull EFI 15A fuse under hood..it'll kill the truck. Then put fuse back in. Re-start it..let it idle, then drive. See if code comes back.
     
  4. Oct 30, 2011 at 8:19 PM
    #4
    Anthony250

    Anthony250 E-Fabber

    Joined:
    Sep 29, 2010
    Member:
    #44016
    Messages:
    3,096
    Gender:
    Male
    First Name:
    Anthony
    San Gabriel Ca
    Vehicle:
    99 Tacoma LT Prerunner
    Eagle Alloy's 058 on Goodyear BFG All Terrians . 265/75/16. Kenwood Stereo, 12" JL Audio Sub. Led Lighting interior. Led Turn Signals. Custom Bumper ,Total Chaos Long travel Sway away shocks, glassworks fenders, ,Spintech Super Pro street muffler, Hellas 500ff HID Converted, Window Tint,Black Emblems, Deckplate, , Deaver Prerunner Pack, Bilstein 7100's 12" SB's and Sway Away 2" Air Bumps
    Hes right it is most likely the Upstream O2 sensor, i have the same light just came on,and I know every thing is good but i have not replaced that 02 sensor.
     
  5. Feb 11, 2012 at 10:36 AM
    #5
    Greensystemsgo

    Greensystemsgo [OP] Self Proclaimed first gen expert :doh:

    Joined:
    Jun 13, 2011
    Member:
    #58216
    Messages:
    2,843
    Gender:
    Male
    First Name:
    Nick
    Avondale, AZ
    Vehicle:
    1999 TRD/SR5 4x4
    5100/5125's All pro expedition leafs Eibach coils Light racing uca's 2004 gauge cluster All stainless brake lines 1" diff drop kenwood with polks rebuild seat support webbing satoshi grill optima red top
    And still the fight continues!
     
  6. Feb 11, 2012 at 10:40 AM
    #6
    G scott04

    G scott04 ...

    Joined:
    Jan 17, 2011
    Member:
    #49443
    Messages:
    5,003
    Gender:
    Male
    First Name:
    Garrett
    Mesa
    Vehicle:
    04 PreRunner
    I must know how you resolve this I think I have the same problem, Im at like a 100 miles at half a tank.
     
  7. Feb 11, 2012 at 11:15 AM
    #7
    Greensystemsgo

    Greensystemsgo [OP] Self Proclaimed first gen expert :doh:

    Joined:
    Jun 13, 2011
    Member:
    #58216
    Messages:
    2,843
    Gender:
    Male
    First Name:
    Nick
    Avondale, AZ
    Vehicle:
    1999 TRD/SR5 4x4
    5100/5125's All pro expedition leafs Eibach coils Light racing uca's 2004 gauge cluster All stainless brake lines 1" diff drop kenwood with polks rebuild seat support webbing satoshi grill optima red top
    It is not the coil. Maaaaaaybe wires. I'm thinking the o2 sensor on cat, or maf. I should do seafoam through gas tank to clean injectors and other stuff.
     
  8. Feb 11, 2012 at 11:30 AM
    #8
    lil J

    lil J Well-Known Member

    Joined:
    Dec 10, 2011
    Member:
    #68544
    Messages:
    162
    Gender:
    Male
    First Name:
    Jacen
    Louisville
    Vehicle:
    99 Tacoma 4wd V6 Horizon Blue
    Old Man Emu Suspension
    Change out your mass air flow sensor, cleaning doesn't work as good as replacing. I had the same problem, except for the exhaust bracket. After I changed the MAF truck was running like new. On the first gen. the MAF is a common problem, don't know what year you got but the sensor is relatively cheap.
     
  9. Feb 11, 2012 at 12:01 PM
    #9
    lil J

    lil J Well-Known Member

    Joined:
    Dec 10, 2011
    Member:
    #68544
    Messages:
    162
    Gender:
    Male
    First Name:
    Jacen
    Louisville
    Vehicle:
    99 Tacoma 4wd V6 Horizon Blue
    Old Man Emu Suspension
    If you do decide to change out the MAF disconnect the battery while before you start so you computer will reset.
     
  10. Feb 11, 2012 at 12:13 PM
    #10
    G scott04

    G scott04 ...

    Joined:
    Jan 17, 2011
    Member:
    #49443
    Messages:
    5,003
    Gender:
    Male
    First Name:
    Garrett
    Mesa
    Vehicle:
    04 PreRunner
    Did you get a new one or a rem? saw one with a core charge at autozone
     
  11. Feb 11, 2012 at 3:02 PM
    #11
    lil J

    lil J Well-Known Member

    Joined:
    Dec 10, 2011
    Member:
    #68544
    Messages:
    162
    Gender:
    Male
    First Name:
    Jacen
    Louisville
    Vehicle:
    99 Tacoma 4wd V6 Horizon Blue
    Old Man Emu Suspension
    got the one with core charge at autozone
     
  12. Mar 26, 2014 at 6:46 PM
    #12
    Archer550

    Archer550 Well-Known Member

    Joined:
    Jan 30, 2012
    Member:
    #71799
    Messages:
    90
    Gender:
    Male
    Winnipeg
    Vehicle:
    04 xtracab TRD MT
    ARB for now
    Zombie i know, but did you (op or others with symptoms) ever figure this one out?
    I got the same thing going on now in my 2004 tacoma
     
  13. Mar 26, 2014 at 6:52 PM
    #13
    oldblue1968chevy

    oldblue1968chevy Well-Known Member

    Joined:
    Nov 26, 2012
    Member:
    #91916
    Messages:
    1,539
    Gender:
    Male
    First Name:
    John
    Spokane WA/Viola TN
    Vehicle:
    2000 Toyota Tacoma V6 TRD
    Stock
    Im at 100 miles @ 1/2 talk no CEL light...

    Granted alot of my driving is short low mileage trips...but didnt seem ALOT better when i drove to seattle (5 hrs)
     
  14. Mar 26, 2014 at 7:09 PM
    #14
    Archer550

    Archer550 Well-Known Member

    Joined:
    Jan 30, 2012
    Member:
    #71799
    Messages:
    90
    Gender:
    Male
    Winnipeg
    Vehicle:
    04 xtracab TRD MT
    ARB for now
    I had this issue on a recent 700km road trip (1400 km total) and noticed on the way out around 10 MPG as well as the cel came on when i romped it on the highway...
    Took it to a dealer (was 700 km from my tools and scanner :( )
    They replaced pcv valve (aparently it had failed), replaced air filter, and cleaned maf. Truck ran okay for the first tank and then boom back to 10 mpg cel on. Next fill up cel back off and somewhere around 14 mpg? The intermitent nature of the porblem is the worst part, ordering a scangauge 2 to monitor faults and A/F real time.
    Gonna do a tune up tomorow as i just noticed the plug wires are from 2004 and i have heard that misfires can cause a lean reading.
     
  15. Mar 26, 2014 at 7:15 PM
    #15
    Greensystemsgo

    Greensystemsgo [OP] Self Proclaimed first gen expert :doh:

    Joined:
    Jun 13, 2011
    Member:
    #58216
    Messages:
    2,843
    Gender:
    Male
    First Name:
    Nick
    Avondale, AZ
    Vehicle:
    1999 TRD/SR5 4x4
    5100/5125's All pro expedition leafs Eibach coils Light racing uca's 2004 gauge cluster All stainless brake lines 1" diff drop kenwood with polks rebuild seat support webbing satoshi grill optima red top
    Replace wires and plugs. Then refer to FSM for coil testing.

    Mine was coils. I ordered all new denso parts from RockAuto.
     
  16. Mar 26, 2014 at 7:18 PM
    #16
    wannabetrd

    wannabetrd Well-Known Member

    Joined:
    Jan 25, 2014
    Member:
    #121441
    Messages:
    127
    Gender:
    Male
    First Name:
    Zach
    Michigan
    Vehicle:
    SR5
    3inch front 2inch rear lift with add a leaf and extended brake lines trd exhaust
    Check all your vacuum lines
     
  17. Mar 26, 2014 at 7:27 PM
    #17
    Archer550

    Archer550 Well-Known Member

    Joined:
    Jan 30, 2012
    Member:
    #71799
    Messages:
    90
    Gender:
    Male
    Winnipeg
    Vehicle:
    04 xtracab TRD MT
    ARB for now
    Will do. Is NGK stuff okay? (for wires and plugs) Its all I can get locally. The local parts store wants nearly $80 for ngk plug wires...

    Considering OEM from conicelli partznet is $55 that seems a little steep.
    Id rather not wait the 1-2 weeks it would take to get stuff from rock or conicelli.
     
  18. Mar 26, 2014 at 7:50 PM
    #18
    Greensystemsgo

    Greensystemsgo [OP] Self Proclaimed first gen expert :doh:

    Joined:
    Jun 13, 2011
    Member:
    #58216
    Messages:
    2,843
    Gender:
    Male
    First Name:
    Nick
    Avondale, AZ
    Vehicle:
    1999 TRD/SR5 4x4
    5100/5125's All pro expedition leafs Eibach coils Light racing uca's 2004 gauge cluster All stainless brake lines 1" diff drop kenwood with polks rebuild seat support webbing satoshi grill optima red top
    Shipping is like 3 or 4 days. And you know it'll be OEM quality cause denso makes Toyotas parts.

    NGK I have zero experience.
     
  19. Mar 26, 2014 at 7:51 PM
    #19
    Greensystemsgo

    Greensystemsgo [OP] Self Proclaimed first gen expert :doh:

    Joined:
    Jun 13, 2011
    Member:
    #58216
    Messages:
    2,843
    Gender:
    Male
    First Name:
    Nick
    Avondale, AZ
    Vehicle:
    1999 TRD/SR5 4x4
    5100/5125's All pro expedition leafs Eibach coils Light racing uca's 2004 gauge cluster All stainless brake lines 1" diff drop kenwood with polks rebuild seat support webbing satoshi grill optima red top
    Nvm, I see your from ca. Check dealer.
     
  20. Mar 26, 2014 at 8:33 PM
    #20
    Archer550

    Archer550 Well-Known Member

    Joined:
    Jan 30, 2012
    Member:
    #71799
    Messages:
    90
    Gender:
    Male
    Winnipeg
    Vehicle:
    04 xtracab TRD MT
    ARB for now
    I fear the dealer prices, i will check tomorow but the parts i bought to do my waterpump and timing belt from conicelli, (around 400) was upwards of 1200 locally.
     
To Top