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Running rich, power loss, crappy mileage

Discussion in 'Technical Chat' started by flesheatingvirus, Nov 19, 2008.

  1. Nov 19, 2008 at 3:13 PM
    #1
    flesheatingvirus

    flesheatingvirus [OP] Well-Known Member

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    My 96 Tacoma 2.4L AT. has a lack of power that makes it difficult to maintain over 60 without riding in 3rd gear. The tailpipe is also very sooty, leading me to believe it is running rich. So far I have or have had checked:

    -vacuum (good)
    -timing (good)
    -fuel pressure (high end of normal)
    -exhaust (no obstructions)
    -MAF sensor (cleaned)
    -tire pressures (good)
    -cylinder compression (good)

    I have replaced:

    -air filter
    -fuel filter
    -PCV valve
    -spark plugs (properly gapped)
    -plug wires
    -both O2 sensors
    -fuel pressure regulator
    -transmission (rebuilt)

    Fuel injector cleaner has also been tried to no avail. I did find a crack just below the exhaust manifold. I'm going to get that fixed soon. I'm running out of ideas for this thing.

    I also always run it with a ScanguageII plugged in. I have never gotten any codes.

    I just figured out that the dealership put in the wrong spark plugs. They put in the single electrode plugs. A sticker under the hood calls for dual electrode plugs only. I just replaced them the other day with no change resulting as of yet.

    I also noticed that when I cover the exhaust with my hand it comes away wet, as well as black. So I held my hand slightly off the end of the pipe, and I could see small flecks of sooty water hitting my hand. I look under the exhaust pipe and see what looks like a sooty water drip trail on the underside. Upon looking inside the tailpipe, I can see water droplets coating the inside. Here are some pics of the underside of the pipe and the bumper behind it that is getting splattered.


    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
     
  2. Nov 19, 2008 at 3:15 PM
    #2
    dually

    dually Low and slow

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    Not as many as the 98..
    Have you run some seafoam through that beast? Reset your ECU???
     
  3. Nov 19, 2008 at 3:18 PM
    #3
    flesheatingvirus

    flesheatingvirus [OP] Well-Known Member

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    After I changed the plugs, I let the battery sit unplugged for about an hour. The Scangauge is still at "Not Ready", so I'll be waiting on that. I just put some Seafoam in the gas tank today. Should I get another can and put it somewhere in the intake? This is the first time I've used this product.
     
  4. Nov 19, 2008 at 3:19 PM
    #4
    dually

    dually Low and slow

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    Not as many as the 98..
    Run seafoam through the vaccum line.
     
  5. Nov 19, 2008 at 3:21 PM
    #5
    dually

    dually Low and slow

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    Not as many as the 98..
    I honestly dont see why you are running rich... are you throwing a CEL?? Have you scanned the ECU for any codes? O2 sensors should have cured any incorrect F/A ratio..
     
  6. Nov 19, 2008 at 3:24 PM
    #6
    flesheatingvirus

    flesheatingvirus [OP] Well-Known Member

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    I'm not getting any codes. I always drive with the ScangaugeII plugged in. The O2 sensors are less than 4 months old. I pulled them today to check on them; all black, of course. Which vacuum line is best for Seafoam; the brake booster? I can't figure out the rich part either. I've been dealing with this for months. Even my mechanics are stumped.
     
  7. Nov 19, 2008 at 3:27 PM
    #7
    dually

    dually Low and slow

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    Not as many as the 98..
  8. Nov 19, 2008 at 3:30 PM
    #8
    flesheatingvirus

    flesheatingvirus [OP] Well-Known Member

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    Thanks! I'll give it a try tomorrow.
     
  9. Nov 19, 2008 at 3:45 PM
    #9
    Brunes

    Brunes abides. Staff Member

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    Yeah...Seafoam helped out my scion a decent bit...it's a bit smoother idling and it's got a cleaner throttle up.
     
  10. Nov 19, 2008 at 3:58 PM
    #10
    chris4x4

    chris4x4 With sufficient thrust, pigs fly just fine. Staff Member

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    4.10 gears, sliders, and lots of buttons.
    Sounds like you have a bad cat. :confused:
     
  11. Nov 20, 2008 at 8:47 AM
    #11
    flesheatingvirus

    flesheatingvirus [OP] Well-Known Member

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    The cat is less than 6 months old. The original was stolen off the truck at the dealer lot before I bought it, and he had it replaced.
     
  12. Nov 20, 2008 at 9:29 AM
    #12
    BeefTaco

    BeefTaco WESTern Alliance: NORCAL COAST

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    I would check a couple of things recheck your fuel pressure readings maybe a problem with your fuel pressure regulator. Also do some pin resistance checks of your MAF for problems with outside air temp readings.
     
  13. Nov 20, 2008 at 9:42 AM
    #13
    flesheatingvirus

    flesheatingvirus [OP] Well-Known Member

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    I just replaced the fuel pressure regulator. No change. I did notice that, when I bought the truck, somebody had rerouted the vacuum hose on the regulator to a T-split on the vacuum hoses for the power steering pump. Since there is stronger vacuum there than at the chamber where it should be connected, I figured that they were trying to hide/compensate for a failing regulator. I guess that wasn't the case.

    I checked the voltage on the MAF sensor according to the Haynes manual. It just states that the voltage should fluctuate when air passes over the wires. How else can I check to see if the MAF is faulty? I also have a spare used MAF sensor that I tried. No change.
     
  14. Nov 20, 2008 at 12:17 PM
    #14
    BeefTaco

    BeefTaco WESTern Alliance: NORCAL COAST

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    Here is a link to some online Toyota service manual's
    there are few other things to check on the maf sensor.
    If the other maf you have is not brand new factory and
    or a known good part I would not trust it.



    http://www.ncttora.com/fsm/index.html
     
  15. Nov 20, 2008 at 12:20 PM
    #15
    -TRDMAN-

    -TRDMAN- ΜΟΛΩΝ ΛΑΒΕ

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    Head gasket????
     
  16. Nov 21, 2008 at 9:00 AM
    #16
    flesheatingvirus

    flesheatingvirus [OP] Well-Known Member

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    If that were the case, wouldn't it have failed the compression test? All 4 cylinders were between 160-180.
     
  17. Nov 21, 2008 at 10:23 AM
    #17
    -TRDMAN-

    -TRDMAN- ΜΟΛΩΝ ΛΑΒΕ

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    I DON'T KNOW PROBLY NOT THE CASE IF THE COMP. IS CORRECT.... NOR WOULD IT BE THE RINGS..... HMMM.... IM STUMPED ON THIS ONE... I WILL SEE WAT THE OLD MAN THINKS(I COME FROM A LONG LINE OF PEOPLE WHO KNOW THEIR SHIT WHEN IT COMES TO VEHICLES...):confused:
     
  18. Nov 21, 2008 at 10:52 AM
    #18
    flesheatingvirus

    flesheatingvirus [OP] Well-Known Member

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    I appreciate it. This has been stumping me for months. I'm getting tired of spending time and money on it. I keep coming back to the MAF sensor. I hesitate on spending $300 on a new one when it MIGHT be the issue. I've heard of them going out and not throwing codes.
     
  19. Apr 10, 2011 at 9:59 PM
    #19
    yotabeast505

    yotabeast505 The Beast

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    here we go. Ford 9" rear after breaking 5 sets of gears in the stock yota 8.8, 5.13 gears with a detroit hard locker, 63" chevy leafs and custom hangers, sky's front spring hanger with sky's extream hysteer and PSC hydro assist ram and PSC pump. welded front spyders in the f-550 front dana 60 with warn hubs, pico brake lines and hoses, elecrtic fan, TRD supercharger with URD 2.1 Pully, URD Map-ECU2 and cage built by me. wide band a/f by inovations, lots and lots more...........
    try pulling the MAF sensor out and spray the wires with electronics cleaner.. if you run a K&N filter this is a MUST ever few months.... let it dry. reinstall and then run the truck for a few days and see if that helps
     
  20. May 21, 2015 at 1:15 PM
    #20
    96coma

    96coma Member

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    to much to post lol
    reviving an old thread, did OP find the issue? my 2.7 is doing the same thing
     
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