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Tacoma Hesitation Problem -- TPS, maybe? --

Discussion in '1st Gen. Tacomas (1995-2004)' started by edavidso, Dec 19, 2010.

  1. Dec 19, 2010 at 10:02 AM
    #1
    edavidso

    edavidso [OP] Well-Known Member

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    3" Toytec Lift, Smitty Roll Bar, Push Bar, Nerf Bars, 7 KC 150W, Viper alarm w/ Remote Start, Pioneer CD/MP3, 6 disc changer, Infiniti Speakers, Rhino Lining.
    Hello!

    I am looking for some words of wisdom. I have a 97 SR5 4x4 3.4L and there is a really bad hesitation on acceleration (and every now-and-then a variation in idle RPM). I recently replaced the spark plugs and wires. No change. I thoroughly cleaned the throttle body. still a hesitation, although increased performance. i was reading that is could be the TPS...i tested mine with the ohm meter; with the analog meter i could see some variation in needle movement when going from closed to open throttle (mainly after initial throttle movement). On the digital meter, i could see some variation, but it was harder to detect.

    Any advice on how to test the TPS so i can make sure I am doing it correctly?

    If the TPS is bad, should I replace just the TPS? I heard that it would need to be professionally adjusted...is this true for this specific truck?

    On the other hand, the local Toyota Salvage has a full throttle body with TPS that I could buy (only $20 more), which would not require professional adjustment...

    Any Advice??!!

    Thanks
     
  2. Dec 19, 2010 at 11:18 AM
    #2
    Janster

    Janster Old & Forgetful

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    Are your injectors clean? How's the fuel pump? How's the fuel filter?
     
  3. Dec 19, 2010 at 12:10 PM
    #3
    edavidso

    edavidso [OP] Well-Known Member

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    3" Toytec Lift, Smitty Roll Bar, Push Bar, Nerf Bars, 7 KC 150W, Viper alarm w/ Remote Start, Pioneer CD/MP3, 6 disc changer, Infiniti Speakers, Rhino Lining.
    Not sure about the injectors, i have never cleaned them in excess of fuel additives for the injectors...fuel filter is brand new...not a new pump tho...any way to test those without just buying new stuff on a whim?
     
  4. Dec 19, 2010 at 1:15 PM
    #4
    skytower

    skytower Well-Known Member

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    Hitch and wiring, aux back-up light, rear strobe lights, radio and underseat sub.
    Do you have coil packs or a distributor? If distributor, replace it and the rotor. If coil packs, look for grey arc marks from the terminals to the frame.
    Check the coil for the distributor for arcs too.
     
  5. Dec 19, 2010 at 1:19 PM
    #5
    Janster

    Janster Old & Forgetful

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    3.4L has coil packs

    To OP: Unfortunately, I don't know enough to say how to check fuel pump or fuel pressure. Perhaps some searching on www.google.com?
     
  6. Dec 19, 2010 at 1:41 PM
    #6
    brelandt

    brelandt Well-Known Member

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    I know this sounds dumb but it makes a huge difference on your fuel system. How cold is your engine running? Is your T-stat stuck open? Bad Rad cap? If the engine is not running at the correct temp you can get some weird fuel problems from droplets and stuff. Has the gas mileage gotten worse lately?
    Not enough information given to say for sure what is wrong. Almost impossible to do a google search on this as there are way too many things that will cause this. Fuel, cooling, electrical, you name it.
     
  7. Dec 19, 2010 at 7:49 PM
    #7
    edavidso

    edavidso [OP] Well-Known Member

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    3" Toytec Lift, Smitty Roll Bar, Push Bar, Nerf Bars, 7 KC 150W, Viper alarm w/ Remote Start, Pioneer CD/MP3, 6 disc changer, Infiniti Speakers, Rhino Lining.
    I have tested the coils...seemed to be within spec according to my readings...I have no idea about the thermostat tho...never really though about it...and yes, the gas mileage has seemed to decrease lately. Any way of finding out whether its the t-stat? Where is that located? i dont know if it matters, but the temp gauge is in the norm every time i drive it.

    thanks for the help from all!!!
     
  8. Dec 19, 2010 at 7:54 PM
    #8
    Graham

    Graham Pay it Forward

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  9. Dec 19, 2010 at 8:01 PM
    #9
    edavidso

    edavidso [OP] Well-Known Member

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    3" Toytec Lift, Smitty Roll Bar, Push Bar, Nerf Bars, 7 KC 150W, Viper alarm w/ Remote Start, Pioneer CD/MP3, 6 disc changer, Infiniti Speakers, Rhino Lining.
    Interesting, however I have cleaned the air filter recently (K&N) and havent hit any trees to tear off the wheel well liner ...:) Im not sure if air flow is the problem. mine happens in any type of weather, at slow speeds and highway acceleration.

    Stupid question...what is the MAF?? I see it posted here as a potential problem...sorry im dumb...
     
  10. Dec 19, 2010 at 8:38 PM
    #10
    brelandt

    brelandt Well-Known Member

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    Mass Air Flow meter. Don't worry about not know what something means, it's cool. I'm studing auto mechaincs in college and I was a jet engine mech for 8 years and I ask what things mean all the time.
    T-stat in the Toyota is just under the upper rad hose where it connects to the engine side. It's important to check your coolant. Antifreeze provides lub to your pump and if it's old or anything in the system isn't right you get some odd things happening. The temp gauge my be right but the tolerances in them are bad. just something to look at so that you can say for certain that you have eleminated everything. No ideal of your mileage or maintenance in the past.
     
  11. Dec 20, 2010 at 4:06 AM
    #11
    Janster

    Janster Old & Forgetful

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    Have you had any *check engine lights* come on?

    Just in case your dash light isn't working....and you can't see the CEL light on, I would take the truck down to a local auto parts store that offers free diagnostic checks (check engine codes for free). See if there are any codes in the computer.

    Have you ever changed any of your O2 sensors?
     
  12. Dec 20, 2010 at 8:11 AM
    #12
    Southern01Taco

    Southern01Taco Well-Known Member

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    I would check your maf. When I got my truck it had a bad hesitation and when I was in a higher gear and gave it alot of gas it would almost die. I tried changing the plugs, fuel filter, and the fuel pump. Then I changed the maf and it fixed it.
     
  13. Dec 20, 2010 at 4:07 PM
    #13
    edavidso

    edavidso [OP] Well-Known Member

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    3" Toytec Lift, Smitty Roll Bar, Push Bar, Nerf Bars, 7 KC 150W, Viper alarm w/ Remote Start, Pioneer CD/MP3, 6 disc changer, Infiniti Speakers, Rhino Lining.
    Check engine light is on...and honestly I havent checked it since it came on last...the past few times it came on it was saying "cylinder 6 misfire" so i replaced the plug wires and it helped for about a month...then it came back on with the same hesitation issue, so I thought it was the same message...

    Maybe ill try changing the MAF, is it like changing the TPS, where it will need adjustment, or a basic replacement? I also have to replace the coolant...it has been a while...

    And...the O2 sensors are brand new as well...needless to say I have been trying to tackle this for a while...hoping its not something too expensive.

    The truck has 230000 miles...so it may just be running out of life...hope not! I love my truck...going for at least 400000 miles...!!! :)

    Thanks again for all the input...
     
  14. Dec 20, 2010 at 7:25 PM
    #14
    skytower

    skytower Well-Known Member

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    I doubt it's the MAF. Probably a spark leakage/misfire problem. Just because the coil is good doesn't mean it's not arcing to ground. Spray a light mist of water on the wires and coils, in the dark, and look for arcs.
    Could also be an air leak after the MAF which opens with a pull from engine torque. Old bellows crack and leak unmetered air=stall/hesitation.
     
  15. Dec 21, 2010 at 4:01 AM
    #15
    Janster

    Janster Old & Forgetful

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    What's the CEL code?

    Here's some information you might want to read:
    http://www.customtacos.com/forum/showthread.php?t=61955
     
  16. Dec 24, 2010 at 3:14 AM
    #16
    Graham

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    I agree that it sounds like an air leak somewhere. I had the cylinder misfire error code as well and tried everything till I came upon the airflow issue.
     
  17. Dec 24, 2010 at 12:51 PM
    #17
    saweetlou

    saweetlou Well-Known Member

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    Hey just a thought, I had a similar problem and it turned out to be that one of my sparkplug boots had a crack in it(#3 I think) If cel is telling you 6 is bad check the boot for cracks
     
  18. Jan 5, 2011 at 9:51 AM
    #18
    edavidso

    edavidso [OP] Well-Known Member

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    3" Toytec Lift, Smitty Roll Bar, Push Bar, Nerf Bars, 7 KC 150W, Viper alarm w/ Remote Start, Pioneer CD/MP3, 6 disc changer, Infiniti Speakers, Rhino Lining.
    Sorry for the long delay in responses...had to get through the holidays!

    I replaced the plug wires and the three boots that came with the replacement kit. So i dont think it could be a boot, unless it is in fact the coil that is causing the problem, bucause the kit only replaces the wires/boots leading from the coils on the left of the engine. It doesnt replace anything having to do with the coils themselves. I will try to check the coils again today.

    So i finally got the CEL code...the first read "Cylinder 3 misfire", same as before but with a different cylinder...

    Second read "throttle/position sensor A circuit" --

    Forgot to write the actual numbers down...

    Could this still be an airflow problem, even with the TPS being mentioned?

    Also, when I cleaned the Throttle Body, after putting everything back together, the engine idles about 300-700 RPM higher than it used to...???
     
  19. Jan 5, 2011 at 11:48 AM
    #19
    shampoop

    shampoop Well-Known Member

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    as for the "throttle/posiiton sensor A circuit" code, I actually just did that on a 4 runner a few weeks back. The guy had the same intermittent hesitation complaint. There are many different tests to check if the TPS is working correctly.

    What it boils down to though is that extremely often according to identifix, every test you do will show that there is nothing wrong with the TPS at all, that everything is perfect, except that if you replace it it will fix the problem and the code will go away. I know it doesn't make sense i was very skeptical at first but it's a super common thing and this fixed it every time.

    also, i didn't see you mention the spark plugs. Have you checked them yet? How many miles does your truck have? Plugs last so long on modern cars it's easy to forget about them.
     
  20. Jan 5, 2011 at 1:19 PM
    #20
    skytower

    skytower Well-Known Member

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    Since it moved when you replaced ignition parts, it makes me think spark leakage even more. Are all the spark plugs, wires and boots new? If not, replace them.
     
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