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Hesitation

Discussion in '80-Series Tech' started by landtoy80, Apr 15, 2003.

  1. landtoy80

    landtoy80

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    When I snap the accelerator I get a hesitation. It only does it if I snap the acc. in N and if I floor it in gear I hear a knock like sound. If I just rev the motor or normal start from stop there is no problem. In N and I snap the acc. I hear a sucking of air sound fron the intake and then the motor revs up. I checked the cap and cleaned the posts but they were not bad is it less then a year old. The plugs wires rotor PCV are all less than a year old. Could this be a cat problem or what?
    kurt 94fzj80 219k mi
     
  2. cruiserdan

    cruiserdan SupportingVendor Emeritus Supporting Vendor Moderator

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    Kurt,

    I do not know if this would cause this but check the air intake hose from the airflow meter to the throttle body. It may be cracked. I have seen a few 93/94 vehicles where this has happened. The engine "flatspots" when it torques as it opens up a crack in the inlet hose as the engine rocks.

    REgards.......Dan :beer:
     
  3. Beowulf

    Beowulf

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    Kurt,
    You also mentioned a knocking sound. Based on your description, that could be broken motor mount. Normally you would hear it as a "thud" when the engine drops back on the mount. A broken mount would exacerbate the problem of a cracked air intake hose.

    If the hose is original then you might have the cracks underneath and you might not be able to see them until you stretch the hose. A cracked hose causes a lot of problems including poor idling.

    Keep us posted.
    -B-
     
  4. landtoy80

    landtoy80

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    I just had it off today, should of checked it. It has no problem in any other rpm. Just when I snap the throttle wide open. So the motor doesn't have a chance to rock as it hasn't rev up yet.
    kurt
     
  5. landtoy80

    landtoy80

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    I took off the intake hose and it looks ok. I pluged one end and blowed air into it and no leaks or cracks.
    I looked into the throttle body and the intake is covered with carbon and or oil from PCV.
    I tried to start motor with the air intake hose off and it wouldn't run. Should it run without it?
    What rpm should it run at idle?
    kurt
     
  6. landtoy80

    landtoy80

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    I have a sound like 'air sucking throgh a hose' comming from inside the air intake chamber. It is from under the area of the brake booster vacuum port. When I put my hand on the intake chamber is the sound get quiet. I remove the brake vacuum port to check for a leak but didn't change the sound. I listened under the chamber and it wasn't comming from there.
    Should there be a air sucking sound comming from the air intake chamber under the brake booster port?
     
  7. landtoy80

    landtoy80

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    The sound I get is the same as natural gas going through the gas metter on the house. Is this normal?
    kurt
     
  8. Beowulf

    Beowulf

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    Kurt,

    >> I looked into the throttle body and the intake <<
    >> is covered with carbon and or oil from PCV. <<

    Normal.
    -B-
     
  9. landtoy80

    landtoy80

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    After cleaning the air intake chamber I still have hesitation. I asked dealer and he said it could be dirty injectors and they want $100+ to clean. He said they can hook up their computer and drive for $90+. I check the throttle position sensor but didn't do the test with the feeler guage. I tested the MAF and IAC.
    kurt
     
  10. Beowulf

    Beowulf

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    Kurt,

    We're repeating here but as C-Dan said 3 weeks ago...

    This hose is a known and frequent cause of hesitation problems with high mileage 1FZ-FE engines. Your truck has the original with 220k miles. Unless you are certain it cannot be the cause of the hesitation and it is not leaking then please take another look at it. The cracks are not easy to see.

    -B-
     
  11. landtoy80

    landtoy80

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    I will check again. But the hesitation is before the motor revs up. I could see if it was after the motor reved up and rocked but the motor doesn't move when I snap the accelerator. I can hear the air go into the MAF and into the throttle body then it revs up. From what I have read in other posts it has a flat spot at a certian rpm. It is like it is not getting fuel fast enough or too much , I can't tell. I will soap the tube up and hook one end up to shop vac and run on blower.
    kurt
     
  12. Junk

    Junk

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    fuel filter maybe? Mine had those symptons last year around this time and everyone pooped on the thought it could be the filter - well, it was. just a thought
     
  13. landtoy80

    landtoy80

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    I replaced it after I ran the Toyota fuel injection cleaner through the gas tank last year. I have the old one i think. I could put it on and test but it looked very old. I wounder If I could ream it out and try?
    kurt
     
  14. yomama

    yomama

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    That could most certainly cause you more problems. There is crap floating around your tank all the time, not filtering it would certainly put you in "injector hell" :slap:
    I am not certain I understand your problem? Every vehicle I have ever owned has had a slight hesitation when I stomp on the "go pedal".

    Yomama
     
  15. landtoy80

    landtoy80

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    That is what I would like to know. Is my problem a problem or not? Other than when I stomp on it, there is no problem.
    kurt
     
  16. yomama

    yomama

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    landtoy80,

    I would say that you don't have a problem. Unless, there is some sputtering, or hesitation after the initial lag. It is just the characteristic of a engine, that when you stomp on it there is going to be some initial lag to start it racing through the RPM's. Like I say if it doesn't happen on its way to 5k RPM then you are normal, now if say at 2k RPM you had a drop and then surge, then you have a problem.

    Yomama
     
  17. landtoy80

    landtoy80

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    It only does it from idle. No problems at any other rpm.
    kurt
     
  18. semlin

    semlin rocker

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    Kurt what is the connection you are making between runnign toyota fuel injection cleaner through your gas tank and replacing the fuel filter? I just ran the toyota injector cleaner through my tank. Is it going to clog my fuel filter next?
     
  19. landtoy80

    landtoy80

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    When I got the Toyota FI cleaner from dealer he also gave me a card that said to run the tank of gas and cleaner through with in a day or so. It said that it will eat the tank or lines if you leave it in there to long. So dump it in and have fun. Run the tank to empty and get it full of gas.

    How does the Toyota FI cleaner compair to the FI cleaner the dealer (BG) uses a machine to run it through the FI?
    kurt
     
  20. semlin

    semlin rocker

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    Kurt, that's odd, no such warning with mine. The instructions said add it to a full tank so I did. I am almost ready to fill up five days later.