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[Update] Running down the road; sudden loss in power.

Thread in 'Help Forum' started by Proffitt, May 11, 2018.

  1. Proffitt

    Proffitt Member

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    2001 Ford Explorer Sport Trac (Automatic 4.0l SOHC)

    I was headed to my college to take a final exam when my vehicle lost an enormous amount of power. I was going up an incline and noticed I was slowing down a bit and once my speed was low I dropped down to 2nd gear to make it the rest of the way (Past few months I've had to drop to 2nd to make it up steep inclines idk if this is bad to do- still trying to figure out accel. issue). This time when I dropped to 2nd my vehicle died pedals stiff etc and I pulled off the side of the road. Started back up, put in drive and had almost no acceleration at all.

    All the way to the house had no acceleration even on flat road and can't rev past ~2500 rpm. I've been researching a lot and have attempted to change/clean things, but so far nothing has helped.

    The only codes I get are P1120 & P1121 - both deal with 'Throttle Position Sensor', which apparently my TPS has not been functional on the vehicle for a year+.

    Other Symptoms:
    -Stiff pedals (No crazy stiff, but noticeably stiffer)
    -Crazy Low acceleration
    -Max Speed (Flat surface) ~30mph

    Other Recent Events
    -Went in 4wd for the first time in years just prior to this

    Any help or suggestions will be much appreciated.
     
  2. EddieS'04

    EddieS'04 Well-Known Member 1st Gen Owner 2 Wheel Drive V6 Engine

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    Replace the TPS and make sure you get one that rotates the right way. With the TPS off. Check rotation of the throtle body under the hood. If that is normal. disconect the throttle cable, make sure it slides smooth in the sheath.
     
  3. Proffitt

    Proffitt Member

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    Thank you for the advice, I have an order placed for the correct TPS, but do you think the vehicle would be acting such a way from this one problem? From what I've been researching the vehicle might be in "limp-home-mode" and I don't know if a nonfunctional TPS would trigger this.
     
  4. EddieS'04

    EddieS'04 Well-Known Member 1st Gen Owner 2 Wheel Drive V6 Engine

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    image001.gif image003.gif image005.gif To my knowledge. I think the TPS is one of the sensors, to create limp mode. Its' varible voltage signal has to relate the throttle position to the ECU. The same as the Mass air flow sensor relates the air flow.
    You might want to use some elec cleaner and wash the maf sensor wires. Be carefull dont touch them. They are very sesitive.

    As a sujestion when you replace the TPS. If you have a volt meter. Key on engine off. Check the reference voltage, should be 5vdc. Also check the varible voltage, by rotating the throttle. That should be just below 1vdc to 5vdc. Full open throttle usually stops at 4.75vdc. If the starting voltage is at 1vdc or above. loosen the screws and reset the tps below 1vdc. I will try to find the project and post it.
     
    Last edited: May 14, 2018
  5. EddieS'04

    EddieS'04 Well-Known Member 1st Gen Owner 2 Wheel Drive V6 Engine

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  6. Proffitt

    Proffitt Member

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    Replaced TPS - tps is working perfectly etc - but I'm still having the same issue. I now have zero codes and still stuck in what I think is limp-home-mode ???
     
  7. Todd Z

    Todd Z Well-Known Member 2nd Gen Owner V6 Engine V8 Engine

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    Could be a clogged converter, do you hear a hissing or choking sound in the tailpipe?

    Can remove the 3 bolts in the front of the converter and see if it gets the power back.

    Also have to check fuel pressure.
     
  8. Proffitt

    Proffitt Member

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    Ohhhh Toddy todd..... This does in fact seem to be the issue, I actually not 5 min ago finally removed the entire catalytic converter to see what's been clogging it. 2 days ago I ran across a video that perfectly described the issue....
    Free advert for its help :

    A picture ... on the inside...

    upload_2018-5-20_21-12-57.png

    I would say that ~35% of the inside is clogged.

    Checked prior to this by removing the O2? sensor located before the exhaust reached the cat, and could instantly tell a better performance, though still only reached a top-speed of 40mph, so the highway wasn't too fun. :)

    My only issue with this being the solution to the problem is that the issue was such a sudden change, I'm very skeptical that this will 100% fix the actual issue. I took the entire cat off cause I was certain that for such a sudden change it must have busted the insides, but luckily...
     
  9. Todd Z

    Todd Z Well-Known Member 2nd Gen Owner V6 Engine V8 Engine

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    The OEM cat has several layers..... That's just 1 of the 2 or 3 you can see. Good luck, Hopefully you find it.
     
  10. Proffitt

    Proffitt Member

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    What do you mean "several layers"?

    This is a picture of an identical part...
    [​IMG]

    Left side (3-bolt) is the intake side.

    Are there layers in between each cat? or were you referring to the two combined cats shown above as the layers? (I assume this is considered as two cats connected; each has the honeycomb inside)



    Other:
    - An interesting thing about this was that when I was taking this part off I had ran the engine for a moment, to pull onto flat surface, and the front cat got hot enough you couldn't touch, while the back cat was only warm. I would assume this would happen naturally, but to such an intense difference between the two cats, idk. I've seen people use laser temp gauges to identify where the clog likely is, so I figure this presented that the front cat was the main issue.
     
    Last edited: May 21, 2018
  11. EddieS'04

    EddieS'04 Well-Known Member 1st Gen Owner 2 Wheel Drive V6 Engine

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    The layers that Todd mentioned, is. Some cats' have multiple honeycombs internaly, of different materials. Each layer has different process to clean the exhaust.

    You should also take a look at the 2 cats closest to the engine. If they also are pluged. Depending on where you live. You may not have to replace them. Have a Y-pipe made or buy the RT-Y pipe. As some of us have.
     
  12. Todd Z

    Todd Z Well-Known Member 2nd Gen Owner V6 Engine V8 Engine

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    The cat gets hot because its restricting flow..... They are chambered as Eddie stated, inside each belly there are 2 or more honey combs.... Kind of looking at an old toaster with the toast up if that helps. All the ones I took apart and punched out were at least... LOL
     

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